dDn-C26 data unambiguously if perhaps qualitatively reflect changes in precipitation despite potentially confounding influences of vegetation type and other factors. "The dD values of the fatty acids from land-plant sources (n-C26, n-C28, n-C30) were significantly correlated to one another in each site"
dDn-C26 data unambiguously if perhaps qualitatively reflect changes in precipitation despite potentially confounding influences of vegetation type and other factors. "The dD values of the fatty acids from land-plant sources (n-C26, n-C28, n-C30) were significantly correlated to one another in each site"
dDn-C26 data unambiguously if perhaps qualitatively reflect changes in precipitation despite potentially confounding influences of vegetation type and other factors. "The dD values of the fatty acids from land-plant sources (n-C26, n-C28, n-C30) were significantly correlated to one another in each site"
d18O (3 yr mean) calibration to SST (3 yr mean). SST is inferred from air temperature
d18O (3 yr mean) calibration to SST (3 yr mean). SST is inferred from air temperature
This tracer responds to water temperature through a temperature- dependent fractionation [;?0.2? d18O/i¿½C (19, 20)], as well as to changes in rainfall, due to the influence of isotopically light (more negative d18O) rainfall on surface ocean composition. Because SST and rainfall are intimately linked in tropical areas of strong convective rainfall such as the western equatorial Pacific, the two factors combine to produce an enhanced climatic signal in coral skeletal d18O.
This tracer responds to water temperature through a temperature- dependent fractionation [;?0.2? d18O/i¿½C (19, 20)], as well as to changes in rainfall, due to the influence of isotopically light (more negative d18O) rainfall on surface ocean composition. Because SST and rainfall are intimately linked in tropical areas of strong convective rainfall such as the western equatorial Pacific, the two factors combine to produce an enhanced climatic signal in coral skeletal d18O.
The mean annual cycles of d18O and the Sr/Ca ratios suggest temperature amplitudes of only 40-50% of the 8.4i¿½C in recent temperatures. The results indicated by the proxies appear unrealistically low, and we believe that the data sets do not capture the full annual amplitude, despite a sampling resolution of more than 12 samples per annual skeletal growth increment.
The annual variability of the Bunaken coral d18O refects the seasonal cycle of both salinity and temperature in the surrounding seawater
oxygen isotope record mainly reflects the seasonal SST cycle of 1a€“2 C at this location
This paper examines three methods of determining d18Osw and salinity from coral d18O and Sr/Ca. The give similar resutls and are very dependant on SSS data source for calibration.
Interannual variability in the MS01 coral d18O for 1910a€“ 1997 is clearly dominated by changes in d18Ow because SSTs reconstructed from the coral d18O span 5C [Gagan et al., 1998], while the GOSTA SST range is only 1C (Figure 1). Comparison of local SSTs and rainfall with the coral d18O record shows that d18O increases when SST and rainfall decrease during El NinEœo events
We find strong correlations between coral y18O, precipitation, and OLR, but also between coral y18O and SST
We find strong correlations between coral y18O, precipitation, and OLR, but also between coral y18O and SST
These results suggest that changes in Guam ?18Ocoral are mainly influenced by SST and SSS variations on seasonal and interannual timescales.
The average interannual ?18O variability at Tobago represents a ?SST of ~1.0i¿½C from one year to the next, about 3.5 times the instrumental ?SST value. This disagreement implies that there are significant interannual changes in salinity responsible for the ?18O of the corals from Tobago.
The average interannual ?18O variability at Tobago represents a ?SST of ~1.0i¿½C from one year to the next, about 3.5 times the instrumental ?SST value. This disagreement implies that there are significant interannual changes in salinity responsible for the ?18O of the corals from Tobago.
Coral d18O variations at Rabaul are likely driven by the combined variations in SST and seawater d18O (and hence SSS) given the general climatology of the WPWP
IOD  upwelling  cools  the ambient  SST  and  decreases  rainfall,  both  of  which  increase coral d18O.
However, the long-term trends in the raw d18O and Sr/Ca data provide a strong indication that the ocean surface waters near Bermuda were fresher during the LIA, even if we cannot quantitatively partition the temperature and salinity signals. Over the course of the 200-year record, long-term trends in mean annual and wintertime dOc (0.0003%/a and < 0.0001%/a, respectively) are effectively flat (Figures 4a and 4b). If dOc were purely a result of SST, and SST is increasing through time, a strong negative trend would be visible in the dOc records [McConnaughey, 1989a, 1989b].
The regression equations presented here are not meant as a quantitative calibration of the Monastraea faveolata paleothermometer, because we do not have monthly seawater d18O during 1993a€“ 2004, but is instead intended to demonstrate the high correlation of d18O to temperature at this site, and that it is reasonable to apply the Leder et al. [1996] calibration slope to these data. Weber and Woodhead [1972] proposed that each coral species has its own carbonate d18Oa€temperature relationship because of the influence of metabolic effects on the d18Oa€temperature relationship. Leder et al. [1996] conducted a thorough calibration study for Montastraea faveolata, utilizing thermister data from next to the coral, regular seawater d18O measurements, and skeletal staining to provide independent time control. Their equation is SST (AºC) = 5.33 a€“ 4.519 (A±0.19) (delta c - delta w)
Both geochemical proxies show a significant correlation with instrumental SST over a 41-year time period on both monthly and mean annual scales. We obtained proxy-SST calibrations that are consistent with previously published studies using other coral species from different regions. Hetzinger 2006 10.1029/2006GC001347
interannual d18OSW variations can largely be explained by months-long changes in precipitation minus evaporation and zonal advection
We found some evidence that skeletal stable isotopic composition may be affected by symbiont clade and suggest this is an important topic for future investigation. If different Symbiodinium clades leave consistent signatures in skeletal geochemical composition, the signature will provide a method to quantify past symbiont shuffling events, important for understanding how corals are likely to respond to climate change.
We found some evidence that skeletal stable isotopic composition may be affected by symbiont clade and suggest this is an important topic for future investigation. If different Symbiodinium clades leave consistent signatures in skeletal geochemical composition, the signature will provide a method to quantify past symbiont shuffling events, important for understanding how corals are likely to respond to climate change.
We found some evidence that skeletal stable isotopic composition may be affected by symbiont clade and suggest this is an important topic for future investigation. If different Symbiodinium clades leave consistent signatures in skeletal geochemical composition, the signature will provide a method to quantify past symbiont shuffling events, important for understanding how corals are likely to respond to climate change.
We found some evidence that skeletal stable isotopic composition may be affected by symbiont clade and suggest this is an important topic for future investigation. If different Symbiodinium clades leave consistent signatures in skeletal geochemical composition, the signature will provide a method to quantify past symbiont shuffling events, important for understanding how corals are likely to respond to climate change.
El Nino events bring warmer and rainier conditions to the Northern Line Islands, conditions which constructively act to decrease coral d18O. The opposite climatic effects occur during cool La Nina extremes, driving an increase in coral d18O. Modern Line Islands coral d18O records are high- ly correlated to the regional-scale NINO3.4 index (defined as the average of instrumental SSTs from 5S to 5N, and from 120 to 170W).
El Nino events bring warmer and rainier conditions to the Northern Line Islands, conditions which constructively act to decrease coral d18O. The opposite climatic effects occur during cool La Nina extremes, driving an increase in coral d18O.
coral-based d18Osw is poorly correlated to local rainfall, and likely reflects ocean advection
coral-based d18Osw is poorly correlated to local rainfall, and likely reflects ocean advection
ENSO dominates d18O on interannual timescales. On decadal and longer timescales, larger scale processes such as PDO likely influence d18O.
coral based d18Osw/SSS lags the precipitation by several months, "Thus, SSS may also be influenced by ocean advection in the nearby seas."
d18O is influenced by multiple environmental parameters (i.e., SST, d18Osw, and SSS, the latter controlled by the P-E balance and oceanic advection) in the Indonesian region
Although empirically determined regression slopes are similar to published SST?d18OCRL fractionation values for P. lutea, in both instances, the per cents of explained variance in the regressions are small. This suggests that factors such as SSS are contributing to Palau d18OCRL variability in the pre-instrumental period.
Although empirically determined regression slopes are similar to published SST?d18OCRL fractionation values for P. lutea, in both instances, the per cents of explained variance in the regressions are small. This suggests that factors such as SSS are contributing to Palau d18OCRL variability in the pre-instrumental period.
ocean-atmosphere climate coupling acts to enhance the IOD-related climate signal captured by coral ?18O over that expected from SST anomalies alone
This sample was collected alive at < 1 m water depth (Quinn 1993). Comparison of the d180 with SST and rainfall records indicates a correlation of 0.71 and 0.54, respectively, over the 13-year interval where data overlaps (Fig. 2). Just as in the precipitation and SST comparison, the correlation is much higher at the annual cycle (coherence of 0.95). There is also a slight suggestion of coherence at the El Nino time scale, but the calibration time series is too short to draw any definitive conclusions. Since the 0.71 correlation between SST and d180 explains only half the variance in the SST record, other factors are obviously responsible for the d180 variations. (Quinn 1996)
Florida bay experiences more evaporation in the summer thus d18O is not additive, warm dry summers, cold wet winters.
Authors suggest that ENSO dominates d18O variations on interannual timescales, while the Asian monsoon system drives decadal variability in d18O at this site
there are some indications from the salinity record for New Caledonia [Quinn et al., 1996b] of interannual changes of as much as 0.5 per mil. The potential impact of a 0.5 per mil interannual salinity variation on d18O seawater enceo n interannucaol ral$ ?80r angefsr om 0.14 per mil [Fairbanks et al., 1997] to 0.15 per mil [Craig and Gordon, 1965]. This effect could explain part of the difference in the seasonal and mean annual slope of d180/SST is discussed above.
Local  precipitation  and  SST  anomalies  at  Nauru,  indicative  of  the  state  of  the  Southern  Oscillation,  are  faithfully  recorded  in  coral  ?80  over  the  100  year  long  time  series  of  the  two  corals  analyzed
“El Junco Lake Atwood and Sachs (2014) showed that the lake water δD was primarily controlled by rainfall rates during El Niño episodes, as opposed to evaporation or water loss through seepage or overflow….changes in rainfall amount are imprinted in the isotopic composition of botryococcenes, with negative (posi- tive) δD values co-occurring with wetter (drier) periods.”
local precipitation isotope data confirm dDprecip is positively associated with temperature
local precipitation isotope data confirm d18Oprecip is positively associated with temperature
correlation to meteorological data
spatial slope (Jouzel et al., 2003)
spatial slope (Jouzel et al., 2003)
spatial slope (Jouzel et al., 2003)
spatial slope (Jouzel et al., 2003)
spatial slope (Jouzel et al., 2003)
spatial slope (Jouzel et al., 2003)
spatial slope (Jouzel et al., 2003)
spatial slope (Jouzel et al., 2003)
spatial slope (Jouzel et al., 2003)
spatial slope (Jouzel et al., 2003)
spatial slope (Jouzel et al., 2003)
spatial slope (Jouzel et al., 2003)
spatial slope (Jouzel et al., 2003)
spatial slope (Jouzel et al., 2003)
spatial slope (Jouzel et al., 2003)
spatial slope (Jouzel et al., 2003)
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
spatial slope (Jouzel et al., 2003)
correlation to meteorological data
correlation to meteorological data, ("...these data provide qualitative support for the hypothesis that temperature, not the amount effect, is the dominant process controlling d18O over the Tibetan Plateau.")
correlation to meteorological data, ("...these data provide qualitative support for the hypothesis that temperature, not the amount effect, is the dominant process controlling d18O over the Tibetan Plateau.")
spatial slope (Jouzel et al., 2003)
spatial slope (Jouzel et al., 2003)
spatial slope (Jouzel et al., 2003)
spatial slope (Jouzel et al., 2003)
correlation to meteorological data
correlation to meteorological data
Schlosser 2002: "the observed variations in d18O cannot be explained using the emperature data. Factors other than temperature, such as changes in atmospheric circulation, must be involved."
spatial slope (Jouzel et al., 2003)
comparison to other paleo records
comparison to other paleo records
comparison to other paleo records
comparison to other paleo records
Comparison with general circulation model results and meteorological data suggest that the Andean high altitude records are primarily controlled by precipitation variability over the Amazon basin.
correlation to meteorological data
spatial slope (Jouzel et al., 2003)
correlation to meteorological data
An abrupt warming (inferred from higher d18O values) occurred between 1910 and 1920 (Fig 6a and b)...
An abrupt warming (inferred from higher d18O values) occurred between 1910 and 1920 (Fig 6a and b)...
An abrupt warming (inferred from higher d18O values) occurred between 1910 and 1920 (Fig 6a and b)...
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
Our previous studies[10,19] have revealed that annual mean I´ 18O in the Malan ice core mainly reflects the summer temperature (high annual mean  I´ 18O value implies warm summer while low annual mean I´ 18O value means  cold summer), and its variation can ex-press the variations of summer temperatures in the large part of the northern Tibetan Plateau.
spatial slope (Jouzel et al., 2003)
This verifies that the amount effect acts as an important control on seasonal-decadal scale variations in the isotopic composition of Everest precipitation. More specifically, precipitation increases during periods of more intense convective activity, resulting in more negative dD. Variations in convective activity (i.e., amount effect) and moisture source region related to changes in atmospheric circulation are the dominant controls on the isotopic composition of precipitation in this region (see auxiliary material).
correlation to meteorological data
spatial slope (Jouzel et al., 2003)
correlation to ERA-Interim data
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data: "A good correlation between 10-year averaged d18O data and Marcha€“November Barnaul temperatures was found (Figure S3, r = 0.83, p < 0.001 for the period 1850a€“1980), suggesting that d18O in precipitation at Belukha glacier is suitable as a proxy of atmospheric temperature, which is in good agreement with previous studies."
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
correlation to sea-ice reconstruction
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
spatial slope (Jouzel et al., 2003)
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
spatial slope from Masson-Delmotte et al., 2008
correlation to meteorological data
correlation to meteorological data
spatial slope (Jouzel et al., 2003)
In central Asia, the firsta€order control on seasonal d18O variability is temperature [AraguA¡sa€AraguA¡s et al., 1998]. A high correlation between temperature and precipitation d18O was found for eastern Tien Shan [Hou et al., 1999]. Accordingly, sections of lower d18O values along the core are interpreted as precipitation falling during cold winter seasons and those with higher d18O values, as precipitation falling during warm summer seasons."
Spatial slope (Jouzel et al., 2003)
correlation to meteorological data, ERA-Interim reanalyses, and spatial slope from Masson-Delmotte et al., 2008.
Calibration with borehole temperature
correlation to ERA-Interim data
NaN
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
spatial slope (Jouzel et al., 2003)
correlation to reanalysis data
correlation to reanalysis data
correlation to reanalysis data
correlation to reanalysis data
correlation to reanalysis data
correlation to reanalysis data
correlation to reanalysis data
correlation to reanalysis data
correlation to reanalysis data
correlation to reanalysis data
correlation to reanalysis data
correlation to reanalysis data
spatial slope (Jouzel et al., 2003)
spatial slope (Jouzel et al., 2003)
correlation to meteorological data
correlation to reanalysis data
correlation to reanalysis data
correlation to meteorological data
correlation to reanalysis data
Three-year running mean significantly correlated to SST Nino 4 region
correlation to meteorological data
On a seasonal scale a high fraction of 18O variability was explained by the seasonal cycle of temperature (60% for the ice cores, 70% for the nearby stations of the Global Network of Isotopes in Precipitation a€“ GNIP). When the seasonality is removed, the correlations decrease for all sites, indicating that factors other than temperature such as changing moisture sources and/or precipitation regimes affect the isotopic signal on this timescale. Post-depositional phenomena may additionally modify the ice core data. On an annual scale, the 18O/temperature relationship was significant at the Fiescherhorn,
spatial slope (Jouzel et al., 2003)
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
spatial slope (Jouzel et al., 2003)
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
correlation to ERAI reanalysis data
spatial slope (Jouzel et al., 2003)
correlation to meteorological data
spatial slope (Jouzel et al., 2003)
spatial slope (Jouzel et al., 2003)
In the warm season (Maya€“October) the isotopic composition depends on local temperatures, but the correlation is not persistent over time, while in the cold season (Novembera€“April), atmospheric circulation is the predominant driver of the ice corea€™s isotopic composition.
In the summer season the isotopic composition depends on the local temperature, while in winter, the atmospheric circulation is the predominant driver of the ice core isotopic composition.
So far, no regional or large-scale climate signal could be identified in Elbrus deuterium excess.
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
These results indicate that besides the general enrichment of the stable isotopes 2H and 180 during ablation (melting and evaporation), the deuterium excess d decreases. These effects can be used to identify those snow layers exposed at the glacier surface during summer time.
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
spatial slope (Jouzel et al., 2003)
correlation to meteorological data
Simple d18O-temperature relations used in polar regions (30), when applied to the d18O decrease of 8 per mil in LGS ice on Huascaran, suggest that air temperatures may have been lower by as much as 8A° to 12A°C at high elevation in the tropics.
Simple d18O-temperature relations used in polar regions (30), when applied to the d18O decrease of 8 per mil in LGS ice on Huascaran, suggest that air temperatures may have been lower by as much as 8A° to 12A°C at high elevation in the tropics.
Simple d18O-temperature relations used in polar regions (30), when applied to the d18O decrease of 8 per mil in LGS ice on Huascaran, suggest that air temperatures may have been lower by as much as 8A° to 12A°C at high elevation in the tropics.
Simple d18O-temperature relations used in polar regions (30), when applied to the d18O decrease of 8 per mil in LGS ice on Huascaran, suggest that air temperatures may have been lower by as much as 8A° to 12A°C at high elevation in the tropics.
Simple d18O-temperature relations used in polar regions (30), when applied to the d18O decrease of 8 per mil in LGS ice on Huascaran, suggest that air temperatures may have been lower by as much as 8A° to 12A°C at high elevation in the tropics.
Spatial correlation between mean d18O and borehole 10-m temperatures (Lorius and Merlivat 1977)
spatial slope (Jouzel et al., 2003)
correlation to meteorological data
correlation to meteorological data
correlation to meteorological data
Spatial correlation between mean d18O and borehole 10-m temperatures (Lorius and Merlivat 1977)
Spatial correlation between mean d18O and borehole 10-m temperatures (Lorius and Merlivat 1977)
spatial slope (Jouzel et al., 2003)
spatial slope (Jouzel et al., 2003)
spatial slope (Jouzel et al., 2003)
spatial slope (Jouzel et al., 2003)
spatial slope (Jouzel et al., 2003)
spatial slope (Jouzel et al., 2003)
spatial slope (Jouzel et al., 2003)
spatial slope (Jouzel et al., 2003)
spatial slope (Jouzel et al., 2003)
spatial slope (Jouzel et al., 2003)
On the basis of a d18O/temperature relation for event-based samples from Jungfraujoch and equally sliced ice core segments from Fiescherhorn for the years 1983/1984 [Schotterer et al., 1997], winter snow (months December, January, February, and March) was defined as snow with d18O< -19permill and summer snow was defined as that with d18O > -15A¸permill (months June, July, August, and September).
However, both observations and isotope modelling results indicate that temperature is the primary control on 18O in the study region (Supplementary Information).
reference to IW15MELD00A
18O of lake water largey controled by 18O of precip, which is attributed primarly to air temperature. The d18OP profiles have been reconstructed from a combination of: (1) estimated changes in MAT during the early to mid-Holocene assuming the modern relation 0.59? d18OP/i¿½C; (2) mid-Holocene paleo-d18OP inferred from peat porewater (described above); (3) minimum d18Olw values during the mid- to late Holocene at Middendorf and Dolgoe Lakes, which likely reflect values that have not been strongly influenced by evaporation; and (4) modern estimated d18OP for each site.
Hypothesised that deep lake temperatures dont change, as recorded by benthic ostracods Thus difference between ostracods and authigenic carbonate relates to temperature
Continuous, high-resolution d18O records from cored sediments of Pyramid Lake, Nevada, indicate that oscillations in the hydrologic balance occurred. When drought occurs in the Sierra Nevada, the flow of the Truckee River is reduced and Pyramid Lake falls or the amount of overflow to Winnemucca Lake basin decreases. This results in increasing d18O values of lake water. For the purposes of this paper, we define ??hydrologic droughts?? as periods during which Dd18O=Dt tends to be positive; that is, times when lake volume (or spill rate) decreases.
stronger zonal atmospheric circulation during the early Holocene remains the most plausable mechanism to explain the strong shifts in the d18O-MAT relation. Temperature equation applied to surface sediment yields essentially modern July temperatures|lake water d18O corresponds with pollen-inferred temperatures.
Trace element (Mg and Sr) concentrations in ostracod shells from Lakes Salpete ?n and Pete ?n Itza ? parallel the ?18O records, suggesting that ?18O records ref ect basin hydrology rather than changes in the isotopic composition of rainfall (Rosenmeier et al., in press). Furthermore, covariance in both ?18O and Mg eliminate temperature as a control on the oxygen isotope record.
Trace element (Mg and Sr) concentrations in ostracod shells from Lakes Salpete ?n and Pete ?n Itza ? parallel the ?18O records, suggesting that ?18O records ref ect basin hydrology rather than changes in the isotopic composition of rainfall (Rosenmeier et al., in press). Furthermore, covariance in both ?18O and Mg eliminate temperature as a control on the oxygen isotope record.
The isotopic records from Lake Igelsj .on provide evidence ofsevera l rapid changes in net precipitation during the Holocene, the most extensive ofwhich occurred between 8300 and 8000 cal BP and around 4000 cal BP, respectively. These climatic shifts, which affected large parts of northern and central Europe, were probably related to large-scale rearrangements of atmospheric circulation patterns"For example, the widely recorded cooling shortly before 8000 cal BP, with inferred records of lowered growth-season temperatures distributed from northern Sweden to Switzerland (Snowball et al., 2002; Tinner and Lotter, 2001), seems to be associated with an increase in effective moisture of equally regional significance. This pattern suggests a  southward displacement ofthe Polar Front across most  of the North Atlantic region, giving rise to cooler summers and drastically altered cyclonic pathways, preferentially during winter seasons.
summer precipitation would impose a shift in the  isotopic composition of the lake water and ultimately  in the d18Odiatom record. More positive d18Odiatom values would suggest a greater contribution of summer rainfall from the Atlantic, bringing warmer temperatures. While more negative d18Odiatom suggests a greater contribution from the colder Arctic air mass.
The unusual dry climate in the MWE was previously attributed to a contraction of the circumpolar vortex that resulted in the atmospheric jet stream remaining to the north of California throughout much of the MWE [Stine, 1994]. Our results support this hypothesis.
Jellybean is an evaporation-insensitive lake; The d18O of Jellybean Lake water (average 20.4 ) was identical to mean annual precipitation ( 20.4 ). We conclude that multi-annual y18 Op variation in this region is not driven by temperature changes alone. We suggest that temporal changes in atmospheric circulation across the St. Elias Mountains are the major control on the oxygen isotope composition of precipitation in the interior of the southern Yukon and hence hydrologically open lakes such as Jellybean.
The salinity and 18O content of the lake water increased as a result of reduced precipitation and/or increased evaporation in the mid- to late 1500s
The salinity and 18O content of the lake water increased as a result of reduced precipitation and/or increased evaporation in the mid- to late 1500s
The salinity and 18O content of the lake water increased as a result of reduced precipitation and/or increased evaporation in the mid- to late 1500s
correlation with Mg/Ca and carbonate mineral concentration.
observed d18O variations over a range of 10%are much larger than water temperature variations, and species- specific differences in ostracod shell calcite formation could have caused. Water temperature alone would have had to change by 421C to engender ad18O shift of about 10%(Stuiver, 1970). Thus,d18O of the lake?s water must have changed considerably in the past reflecting salinity varia- tions at the core site and overalld18O changes of regional precipitation
See section 2.4 in Polissar et al. (2006)
Given the lack of correlation between dDlw and pollen- inferred mean July temperatures (Fig. 6), the downcore dDlw changes likely represent either a change in the ratio of soil water and precipitation utilized by the vegetation and/ or a change in source and pathway of regional precipita- tion. The dDlw data may indicate a heavy reliance of terrestrial plants on cool-season derived soil moisture from 11,000?8000 cal yr BP when conditions were dry. Growing- season precipitation may have been too low to provide sufficient water to the plants. An alternative and not mutually exclusive interpretation is that growing-season precipitation was not enriched in deuterium from 11,000?8000 cal yr BP because the presence of high pressure over the Laurentide ice sheet prevented the northward advection of humid, sub-tropical airmasses that are important for summer precipitation today. Both interpre- tations are consistent with Shuman and Donnelly?s (2006) interpretation that low lake levels prior to ca 8200 cal yr BP resulted from low summer precipitation rates and a high ratio of winter to summer precipitation.
match with pollen based January temperature, C16 n-acids are produced by aquatic plants, and ponds in this region are recharged mainly by winter precipitation (Shuman and Donnelly, 2006, Quat Res, 65:44-56)
The d18O record of the past 3100 years reveals that droughts of greater severity and duration than during the 20th century occurred repeatedly, especially prior to 300 AD. Drought variability was anomalously low during the 20th century; 90% of the variability values during the last 3100 years were greater than the 20th-century average. d18O is strongly correlated with the index of the Pacific Decadal Oscillation (PDO) during the past 100 years, and periodicities of the late- Holocene d18O record are similar to those of the PDO. Furthermore, time series of d18O and atmospheric D14C are generally coherent after 700 AD. Both the Pacific climate and solar irradiance probably played a role in drought occurrence, but their effects were non-stationary through the late Holocene.;a highly significant, positive correlation (r = 0.63, n = 32, p < 0.0001) exists between d18O and the PDO. This pattern can be explained by the negative correlation of the PDO with measured winter (r = 0.44, n = 103, p < 0.001) and summer (r = 0.35, n = 103, p < 0.001) precipitation near Steel Lake. Dry winters likely decrease the proportion of 18O-depleted winter precipitation entering the lake, and dry summers enhance evaporative 18O-enrichment of lake watea highly significant, positive correlation (r = 0.63, n = 32, p < 0.0001) exists between d18O and the PDO. This pattern can be explained by the negative correlation of the PDO with measured winter (r = 0.44, n = 103, p < 0.001) and summer (r = 0.35, n = 103, p < 0.001) precipitation near Steel Lake. Dry winters likely decrease the proportion of 18O-depleted winter precipitation entering the lake, and dry summers enhance evaporative 18O-enrichment of lake wate
18O-enrichment in Marcella Lake water caused by summer effective moisture conditions; These prominent late Holocene changes in effective moisture occurred simultaneously with changes in Aleutian Low circulation patterns over the Gulf of Alaska indicated by Jellybean Lake. The reconstructed climate patterns are consistent with the topographically controlled climatic heterogeneity observed in the coastal mountains and interior valleys of the region today
We argue that a substantial and persistent change in !p is required to change the annual mean values of d18Ow in northern Scandinavia.
The d18O record from the varved sediment from Crevice Lake is a proxy for hydroclimate, particularly discharge of the Yellowstone River, in Yellowstone National Park. Low d18O values are consistent with high flow of the Yellowstone River and, thus, wet winters with deep snow pack. They also correspond in general with tree-ring inferred estimates of increased precipitation in the YNP region. Prior to 2000 cal BP, decreasing d18O values suggest an increasingly wet climate or a gradual shift to winterdominated precipitation
The oxygen isotope composition of ostracod carapaces depends primarily on the d18O composition of the water and the tempera- ture at which carbonates precipitate (Craig, 1965; Stuiver, 1970). In tropical, closed-basin lakes within seasonally dry climates, the d18O value of lake water is controlled primarily by the evaporation to precipitation ratio (E/P) of the lake (Fontes and Gonfiantini, 1967; Gasse et al., 1990). During periods of increased (decreased) E/P ratios, the d18O value of lake water will go up (down) as kinetic fractionation processes lead to an increase (decrease) in concen- trations of 18O relative to 16O. Assuming that long-term tempera- ture changes in the tropics are less likely to affect d18O values in the lake than are changes in the E/P ratio (Covich and Stuiver, 1974; Curtis and Hodell, 1993), the d18O value of ostracod carapaces should indicate variations in the E/P ratio of the lake.
The oxygen isotope composition of ostracod carapaces depends primarily on the d18O composition of the water and the tempera- ture at which carbonates precipitate (Craig, 1965; Stuiver, 1970). In tropical, closed-basin lakes within seasonally dry climates, the d18O value of lake water is controlled primarily by the evaporation to precipitation ratio (E/P) of the lake (Fontes and Gonfiantini, 1967; Gasse et al., 1990). During periods of increased (decreased) E/P ratios, the d18O value of lake water will go up (down) as kinetic fractionation processes lead to an increase (decrease) in concen- trations of 18O relative to 16O. Assuming that long-term tempera- ture changes in the tropics are less likely to affect d18O values in the lake than are changes in the E/P ratio (Covich and Stuiver, 1974; Curtis and Hodell, 1993), the d18O value of ostracod carapaces should indicate variations in the E/P ratio of the lake.
The high d18Oshell values, evaporite minerals, low carbonate content and steadily increasing Na concentration suggest that the salinity of Lake Kuhai remained high in zone 6.
The dD of closed-basin tropical lakes such as Wandakara reflects the hydrologic balance of the lake, with drier conditions causing isotopically enriched lake water due to both the amount effect on precipitation and kinetic fractionation during evaporation from the lake surface, which favors the retention of deuterium relative to hydrogen in the lake water (Craig, 1961).
The dD of closed-basin tropical lakes such as Wandakara reflects the hydrologic balance of the lake, with drier conditions causing isotopically enriched lake water due to both the amount effect on precipitation and kinetic fractionation during evaporation from the lake surface, which favors the retention of deuterium relative to hydrogen in the lake water (Craig, 1961).
The shift toward grassland at AD 1000 must therefore have influenced the ?DC30 record due to biosynthetic fractionation differences between trees and grasses (Hou et al., 2007). Indeed, the enormous amplitude of shifts in ?DC30 relative to ?DC16 likely results from the replacement of forest with C4 grasslands during wet periods?a process driven by humans rather than by climate. The amplified ?DC30 response occurs because of a combination of the amount effect during wet periods and stronger isotopic fractionation by grasses relative to trees, both of which favor isotopically depleted ?DC30 (Hou et al., 2008).
dD values of lake surface water are controlled by the amount of rainfall, its isotopic composition and the amount of mixing with the underlying seawater. As rain also increases the density stratification in the lakes, decreasing mixing, surface water dD values are expected to be significantly lower during wet periods compared with dry periods. Conclusions of the paper are about moisture balance (P-E) in the tropical Pacific.
Sachs and Sachse 2008, GCA , 72:793-806. Conclusions of the paper are about moisture balance (P-E) in the tropical Pacific.
Late Holocene excursions to lower d18Odiatom values suggest a reduc- tion of south-to-north storm trajectories delivered by meridional flow, which likely corresponds to pro- longed intervals when the Aleutian Low pressure system weakened.
Oxygen isotopes point toward maximum evaporative forcing early in the Holocene, by or before 9000 cal. yr BP. Mineralogical indicators of lake salinity decline gradually after 6000 cal. yr BP but freshening was episodically reversed and modern lake geochemistry was achieved late in the Holocene, after 1400 cal. yr BP. The Lateglacial?Holocene transition is marked by an abrupt and sustained geochemical anomaly reflecting reduced evaporative forcing and lake freshening...Oxygen isotopes record a rich spectrum of high-frequency variation interpreted as dominantly transient response to fluid balance change, but are relatively insensitive to low-frequency changes better reflected in sediment mineralogy. Oxygen and carbon isotopes covary closely at high frequencies but are decoupled at low frequencies by longterm lake basin changes in carbon cycling.
Consistent with other records, d18O/d13C records
The dominant role of winter precipitation (Pw) in the waterbalance of Takahula Lake suggests that the lake should be particularly  sensitive to interannual changes in the strength and position  of the AL. A westerly AL corresponds to increased moisture delivery  into interior Alaska, whereas an easterly AL results in storm  systems that cross the Coastal Range and the Alaska Range and cut  off winter moisture supply to interior Alaska
Also, the instrumented lake level of Lake Qinghai and coeval d18OC variations is correlated over the last w50 years (Henderson et al., 2003). Because lake level is influenced by effective moisture, d18OC would be expected to be a good proxy for P/E.
similarity with Crag Cave speleothem (McDermott et al 2001)
Consistent with other records (eg Zhu et al. 2005)
Consistent with other records
D18O variations reflect changing water balance between groudwater inflow and water loss by evaporation (wet-dry cycles).High effective moisture supports more westerly storm trajectories and increased moisture delivery to the central Interior Yukon.
d18O.precipitation over tropical South America controlled by Raleigh-type fractionation (see Vuille & Werner 2005)
Complete replacement of the winter Indian monsoon source with a southeasterly/northwesterly source would deplete ?Dwax by about 35?, which is the amplitude of change observed between the mega- droughts interval and the Holocene. / "Relatively depleted ?Dwax values at Lake Malawi from ~3.1 ka to present likely reflect the modern hydrological controls on ?Dprecip, with source changes constituting a more limited role than the amount effect and overall intensity of the hydrological cycle. "
Our results indicate that during the Medieval Climate Anomaly (MCA) (900-1300 AD) the Pacific Northwest experienced exceptional wetness in winter and that during the Little Ice Age (LIA) (1450-1850 AD) conditions were drier, contrasting with hydroclimatic anomalies in the desert Southwest and consistent with climate dynamics related to the El Nii¿½o Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO).
We interpret dDwax in the Challa sedimentary record as a proxy the strength of the ?East African Monsoon (EAM)?, in the sense that the monsoon strength is defined by zonal wind speed velocities during the two rainy seasons (OND and MAM).
The middle to late Holocene d18O record corresponds with records of El Nii¿½o Southern Oscillation intensification that supports a teleconnection between Rocky Mountain climate and North Pacific sea-surface temperatures at decade to century time scales.
The middle to late Holocene d18O record corresponds with records of El Nii¿½o Southern Oscillation intensification that supports a teleconnection between Rocky Mountain climate and North Pacific sea-surface temperatures at decade to century time scales.
d18O data not explicitly discussed
Our results indicate that during the Medieval Climate Anomaly (MCA) (900-1300 AD) the Pacific Northwest experienced exceptional wetness in winter and that during the Little Ice Age (LIA) (1450-1850 AD) conditions were drier, contrasting with hydroclimatic anomalies in the desert Southwest and consistent with climate dynamics related to the El Nii¿½o Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO).
Our results indicate that during the Medieval Climate Anomaly (MCA) (900-1300 AD) the Pacific Northwest experienced exceptional wetness in winter and that during the Little Ice Age (LIA) (1450-1850 AD) conditions were drier, contrasting with hydroclimatic anomalies in the desert Southwest and consistent with climate dynamics related to the El Nii¿½o Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO).
The remarkable similarity between d2Hwax and regional temperature indicates that d2Hwax is a useful proxy to reconstruct temper- ature at decadal- to sub-centennial-resolution.
The remarkable similarity between d2Hwax and regional temperature indicates that d2Hwax is a useful proxy to reconstruct temper- ature at decadal- to sub-centennial-resolution.
The remarkable similarity between d2Hwax and regional temperature indicates that d2Hwax is a useful proxy to reconstruct temper- ature at decadal- to sub-centennial-resolution.
The remarkable similarity between d2Hwax and regional temperature indicates that d2Hwax is a useful proxy to reconstruct temper- ature at decadal- to sub-centennial-resolution.
The remarkable similarity between d2Hwax and regional temperature indicates that d2Hwax is a useful proxy to reconstruct temper- ature at decadal- to sub-centennial-resolution.
The extent of isotopic enrichment of surface waters from meteoric water is determined by the degree of evaporative enrichment of the water body (Leng and Anderson, 2003). Therefore, ... the ?D of lipids produced by aquatic plants (?Daq) tracks the degree of evaporative isotopic enrichment of lake water from meteoric water...."The relatively D-enriched values (more positive ?D) of ?D25 and ?D27 are consistent with our interpretation that these compounds reflect isotopically enriched lake water."
The extent of isotopic enrichment of surface waters from meteoric water is determined by the degree of evaporative enrichment of the water body (Leng and Anderson, 2003). Therefore, ... the ?D of lipids produced by aquatic plants (?Daq) tracks the degree of evaporative isotopic enrichment of lake water from meteoric water...."The relatively D-enriched values (more positive ?D) of ?D25 and ?D27 are consistent with our interpretation that these compounds reflect isotopically enriched lake water."
dDprecip reflects Australasian monsoon strength based on modern precipitation isotope data from nearby station (Bali). "At Bali, the closest isotopic monitoring site to Lake Lading, over 80% of precipitation measured from July 2003 to June 2006 fell between October and March (61% during Novembera€“February), coinciding with the southernmost extension of the ITCZ associated with summer intensification of the Australasian monsoon (Figure 1c). The weighted Octo- bera€“March average dDprecip during that time period was 18.72%, similar to the weighted annual (Julya€“June) average of 20.42%, reflecting the strong control of wet season dDprecip on the annual average dDprecip [Kurita et al., 2009]. While large-scale changes in atmospheric circulation could certainly cause the relationship between precipitation amount and dDprecip to vary, these modern observations indicate that dDprecip reflects Australasian monsoon strength."
Comparison with NW India
More specifi cally, the ostracod-based oxygen isotope record from El Gancho, Nicaragua, indicates that wetter conditions prevailed from as early as ca. A.D. 600 until the end of the MCA, ca. A.D. 1250. An abrupt shift toward arid conditions occurred during the ~150 yr interval between the MCA and the LIA, and was followed by a generally drier climate that has persisted until present
The effective moisture (ratio of precipitation to evaporation) is considered as the main factor controlling the ?D values of lipid n-alkanes in terrestrial plants (Polissar and Freeman, 2010). In a previous study, the ?D record from a loess profile in the Chinese Loess Plateau displayed a strong correlation to changes in the magnetic susceptibility (MS) over the past 130 ka, and the isoto- pic variation was thought to be strongly affected by aridity (Liu and Huang, 2005). Furthermore, a humidity control experiment in the field verified the correlation between D enrichment and rela- tive humidity (McInerney et al., 2011). A study of lipids from the Santa Barbara Basin from the past 1400 years also revealed the ?D of mid-chain acids to be partially correlated with existing data of drought severity (Li et al., 2011).
The effective moisture (ratio of precipitation to evaporation) is considered as the main factor controlling the ?D values of lipid n-alkanes in terrestrial plants (Polissar and Freeman, 2010). In a previous study, the ?D record from a loess profile in the Chinese Loess Plateau displayed a strong correlation to changes in the magnetic susceptibility (MS) over the past 130 ka, and the isoto- pic variation was thought to be strongly affected by aridity (Liu and Huang, 2005). Furthermore, a humidity control experiment in the field verified the correlation between D enrichment and rela- tive humidity (McInerney et al., 2011). A study of lipids from the Santa Barbara Basin from the past 1400 years also revealed the ?D of mid-chain acids to be partially correlated with existing data of drought severity (Li et al., 2011).
These changes in moisture source have been further linked to SST anomalies (SSTa) in the Kuroshio Extension region of the N Pacific, which exerts steering on atmo- spheric circulation and hence moisture sources to the west coast of N America. ... These positive excursions may be linked to warm Kuroshio Extension SSTa, driv- ing greater amplitude waves in the circulation over the N Pacific entraining subtropical moisture sources but generally associated with drier conditions in coastal southern California. Conversely negative isotopic excursions centered on 300 and 800 yr BP may correspond to more N Pacific moisture flux and wetter conditions in coastal southern California, the former of these perhaps associ- ated with the Little Ice Age. In combination with other proxies recording wet/dry climate regime shifts, the information on mois- ture source from precipitation isotopes may thus be particularly helpful in understanding the dynamical causes of hydroclimate shifts. Warm SST anomaly --> less moisture flux -->more enriched precipitation. "Elevated dD values indi- cate more (sub)tropical moisture sources and/or drier conditions, whereas lower dD values are consistent with N Pacific moisture sources and/or more antecedent precipitation. "
These changes in moisture source have been further linked to SST anomalies (SSTa) in the Kuroshio Extension region of the N Pacific, which exerts steering on atmo- spheric circulation and hence moisture sources to the west coast of N America. ... These positive excursions may be linked to warm Kuroshio Extension SSTa, driv- ing greater amplitude waves in the circulation over the N Pacific entraining subtropical moisture sources but generally associated with drier conditions in coastal southern California. Conversely negative isotopic excursions centered on 300 and 800 yr BP may correspond to more N Pacific moisture flux and wetter conditions in coastal southern California, the former of these perhaps associ- ated with the Little Ice Age. In combination with other proxies recording wet/dry climate regime shifts, the information on mois- ture source from precipitation isotopes may thus be particularly helpful in understanding the dynamical causes of hydroclimate shifts. Warm SST anomaly --> less moisture flux -->more enriched precipitation. "Elevated dD values indi- cate more (sub)tropical moisture sources and/or drier conditions, whereas lower dD values are consistent with N Pacific moisture sources and/or more antecedent precipitation. "
SASM precipitation that falls on the Altiplano is ultimately derived from Atlantic Ocean moisture that has been transported across the Amazon Basin and lifted over the eastern cordillera of the Andes. Altiplano ?Dp thus integrates upstream effects including rainout and moisture recycling over the Amazon Basin, altitude effects associated with upslope moisture transport, and local effects such as the intensity of precipitation (?amount effect?) (Dansgaard, 1964). ... "Increased rainout along this trajectory, as well as increased local precipitation in the Andes, results in more depleted ?Dp, consistent with the continentality and amount effects that dominate ?Dp variability throughout most of tropical South America (Vuille et al., 2003). Accordingly, the intensity of the SASM is significantly negatively correlated with ?18O (and correspondingly ?D) of modern precipitation in the Cen- tral Andes, as well as throughout much of southern tropical South America (Vuille and Werner, 2005).
SASM precipitation that falls on the Altiplano is ultimately derived from Atlantic Ocean moisture that has been transported across the Amazon Basin and lifted over the eastern cordillera of the Andes. Altiplano ?Dp thus integrates upstream effects including rainout and moisture recycling over the Amazon Basin, altitude effects associated with upslope moisture transport, and local effects such as the intensity of precipitation (?amount effect?) (Dansgaard, 1964). ... "Increased rainout along this trajectory, as well as increased local precipitation in the Andes, results in more depleted ?Dp, consistent with the continentality and amount effects that dominate ?Dp variability throughout most of tropical South America (Vuille et al., 2003). Accordingly, the intensity of the SASM is significantly negatively correlated with ?18O (and correspondingly ?D) of modern precipitation in the Cen- tral Andes, as well as throughout much of southern tropical South America (Vuille and Werner, 2005).
Indian source: "Sacred Lake currently receives no Atlantic-derived precipi- tation, and its elevation, northeastern slope exposure, and rainfall seasonality make it particularly susceptible to changes in the Indian Ocean monsoons. In contrast, equatorial lakes in central Kenya (e.g. Lake Naivasha) and the western Rift Valley (e.g. Lake Edward, Uganda/ Congo) receive a mixture of Indian- and Atlantic-derived moisture, and hence are sensitive to both monsoons (Nicholson, 1996). " Moisture transport and temperature influence: "The strength of low-level equatorial westerlies in the Indian Ocean has been linked to East African lake levels as well as Mt. Kenyas glaciers, with stronger (weaker) winds inhibiting (enhanc- ing) precipitation in East Africa (Hastenrath, 2001). Overall, these west- erlies have increased in strength since the 1880s. This important Indian Ocean forcing may explain Sacred Lakes particular sensitivity to these changes, and recent drying may have also been locally enhanced by a re- cent rise in temperature (via an upward shift in the ZMR and/or in- creased evaporation of soil water)"
previously published inferrences: fraction reflects evapotranspiration during the growing season
The moisture variations at Sasikul Lake are consistent with the records in the westerlies-dominated Central Asian and northern Tibetan Plateau, suggesting regionally coherent changes in atmospheric circulation during at least the past millennium.
covariation of d18O and d13C (evaporation)
d18O-d13C covariation
d18O-d13C covariation
El Junco Lake is presumed to have remained fresh and therefore its lake-water dD value is dictated solely by the isotopic composition of precipitation, and the relative rates of evaporation and precipitation. More negative lake-water dD values reflect a greater rate of rainfall relative to evaporation during wet periods. Conclusions of the paper are about moisture balance (P-E) in the tropical Pacific.
It is notable that the periods of d18O enrichment in the core are in agreement with the high relative abundance of the epiphytic, algal symbiont Sorites orbiculus and "The d13C values of Elphidium striatopunctatum co-vary, with d18O values indicating a warm, evaporative basin, where degassing of CO2 from the water leads to the concentration of 13C (Abu-Zied et al., 2011c; Lamb et al., 2002; Leng and Marshall, 2004). Therefore, the values of d18O and d13C were used as an evaporation index in the Shuaiba Lagoon."
Since temperature and precipitation amounts are anticor- related on an interannual timescale (Fig. 5), we interpret low ?D values to indicate both relatively cool and wet conditions. In addition to fluctuations in mean annual precipitation iso- topes, snowmelt and delivery to plants may vary. We suggest that a high proportional contribution of water derived from snowmelt, after relatively long and wet winters with high amounts of snowfall, can further lead to more negative ?D leaf wax values.
Since temperature and precipitation amounts are anticor- related on an interannual timescale (Fig. 5), we interpret low ?D values to indicate both relatively cool and wet conditions. In addition to fluctuations in mean annual precipitation iso- topes, snowmelt and delivery to plants may vary. We suggest that a high proportional contribution of water derived from snowmelt, after relatively long and wet winters with high amounts of snowfall, can further lead to more negative ?D leaf wax values.
Past variability in ?Dwax-corr reflects the combined effects of evaporative enrichment of soil and plant water D/H ratios and temporal variability in the isotopic composition of pre- cipitation, which, in this region, is primarily controlled by the amount effect (8, 27)...Therefore we interpret ?Dwax-corr values as a qualitative indicator of past water availability.
Past variability in ?Dwax-corr reflects the combined effects of evaporative enrichment of soil and plant water D/H ratios and temporal variability in the isotopic composition of pre- cipitation, which, in this region, is primarily controlled by the amount effect (8, 27)...Therefore we interpret ?Dwax-corr values as a qualitative indicator of past water availability.
Past variability in ?Dwax-corr reflects the combined effects of evaporative enrichment of soil and plant water D/H ratios and temporal variability in the isotopic composition of pre- cipitation, which, in this region, is primarily controlled by the amount effect (8, 27)...Therefore we interpret ?Dwax-corr values as a qualitative indicator of past water availability.
Past variability in ?Dwax-corr reflects the combined effects of evaporative enrichment of soil and plant water D/H ratios and temporal variability in the isotopic composition of pre- cipitation, which, in this region, is primarily controlled by the amount effect (8, 27)...Therefore we interpret ?Dwax-corr values as a qualitative indicator of past water availability.
Past variability in ?Dwax-corr reflects the combined effects of evaporative enrichment of soil and plant water D/H ratios and temporal variability in the isotopic composition of pre- cipitation, which, in this region, is primarily controlled by the amount effect (8, 27)...Therefore we interpret ?Dwax-corr values as a qualitative indicator of past water availability.
Past variability in ?Dwax-corr reflects the combined effects of evaporative enrichment of soil and plant water D/H ratios and temporal variability in the isotopic composition of pre- cipitation, which, in this region, is primarily controlled by the amount effect (8, 27)...Therefore we interpret ?Dwax-corr values as a qualitative indicator of past water availability.
Carbonate record consists of ikaite-derived calcite; Negative correlation between amount of precipitation and west wind intensity (Mayr et al., 2007; Garreaud et al., 2013)
Located in southern Ghana, the climate of Lake Bosumtwi is heavily influenced by the West African monsoon, which draws moisture onshore from the Gulf of Guineaduring the months of April-October as the monsoon trough migrates northward with the sun (Fig. S2). In winter the winds reverse, and the climate of southern Ghana is influenced by hot, dry northeasterly monsoon winds, which inhibit precipitation over much of North Africa.
If the d18O signal is controlled mainly by E/P, then the variation in d18O during the late Holocene suggests repeated multi-decadal wet/dry cycles that are superimposed upon longer-term, millennial patterns of abundant rainfall and drought.
If the d18O signal is controlled mainly by E/P, then the variation in d18O during the late Holocene suggests repeated multi-decadal wet/dry cycles that are superimposed upon longer-term, millennial patterns of abundant rainfall and drought.
the response of d180L to the temperature controlled variations in d18Op will be characteristic for each lake and, therefore, must be evaluated by hydrological investigations for any lake used for paleoclimatic reconstructions...d18OL of Lake Ammersee proved to be sensitive to mean air temperature variations with periods higher than 10 years and amplitudes larger than 0.3 Kelvin.
If the d18O signal is controlled mainly by E/P, then the variation in d18O during the late Holocene suggests repeated multi-decadal wet/dry cycles that are superimposed upon longer-term, millennial patterns of abundant rainfall and drought.
UK37 calibration to SST
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Since d18Ow is linearly related to salinity, it is possible to reconstruct paleosalinity if an independent estimate of temperature is available [Duplessy et al., 1991; Rostek et al., 1993]. Here we use the d18O of the planktic foraminifer Neogloboquadrina pachyderma (dextral) and the alkenone temperature record for estimating paleosalinity variations.
UK37 calibration to SST
Alkenone concentration calibration to SST
In Arctic water there is no difference between d18O values obtained from N. pachyderma (sin.) and N. pachyderma (dex.), while the differences increase going eastward in the Nordic Seas and into warmer Atlantic water masses [Johannessen, 1992]. Thus the varying contrast between the d18O of N. pachyderma (dex.) and N. pachyderma (sin.) can be used as an indicator of horizontal migration of the Arctic water/Atlantic water interface (Arctic Front).
In Arctic water there is no difference between d18O values obtained from N. pachyderma (sin.) and N. pachyderma (dex.), while the differences increase going eastward in the Nordic Seas and into warmer Atlantic water masses [Johannessen, 1992]. Thus the varying contrast between the d18O of N. pachyderma (dex.) and N. pachyderma (sin.) can be used as an indicator of horizontal migration of the Arctic water/Atlantic water interface (Arctic Front).
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Alkenone calibration to SST
UK37 calibration to SST
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The ?18O of planktonic foraminiferal calcite is a function of two independent variables, the temperature at the time of calcification and the oxygen isotopic composition of seawater, with the latter variable being a measure of local salinity
The ?18O of planktonic foraminiferal calcite is a function of two independent variables, the temperature at the time of calcification and the oxygen isotopic composition of seawater, with the latter variable being a measure of local salinity
A compilation of the _18O of modern Foraminifera, water temperature and salinity indicates that the isotopic composition of North Iceland Shelf Foraminifera is controlled primarily by temperature (Smith, 2001; Smith et al., in review). For example, Smith et al. (in review) found that a strong correlation (r21/40.74) exists between temperatures in the upper 50m of the water column and _18O of the planktonic species N. pachyderma (s). It is not surprising that foraminiferal _18O in this region is controlled primarily by temperature because modern hydrographic changes in North Iceland Shelf waters are dominated by temperature changes, with salinity playing a minor role (Smith, 2001; Smith et al., in review). The effects of temperature versus salinity on the _18O of North Iceland Shelf Foraminifera is discussed at length in a companion paper by Smith et al. (in review), which examines the same _18O records presented in this study.
used to infer freshwater discharge from Congo river
not used in study
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Mg/Ca calibration to SST
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Mg/Ca calibration to SST (G. ruber white)
Mg/Ca calibration to SST
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Mg/Ca calibration to SST
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Mg/Ca calibration to SST
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Mg/Ca calibration to SST
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Mg/Ca calibration to SST
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in areas of strong contrast between the d D value of precipitation and seawater, and high amounts of rainfall (e.g., in the tropics close to river deltas), any changes in alkenone d D values caused by species or growth rate variations are likely to be secondary to the first order effects caused by freshwater fluxes.
in areas of strong contrast between the d D value of precipitation and seawater, and high amounts of rainfall (e.g., in the tropics close to river deltas), any changes in alkenone d D values caused by species or growth rate variations are likely to be secondary to the first order effects caused by freshwater fluxes.
Mg/Ca calibration to SST
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Mg/Ca calibration to SST
Mg/Ca calibration to SST
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The site is also located within the Pacific Warm Pool (7), where the ?18O and Mg/Ca of planktonic foraminifera record the temperature and salinity of western tropical Pacific surface water (8, 9).
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To estimate the paleosalinity (S; psu) from the d18Oswcorr, the regional d18Oswcorr?salinity relationship for the eastern equatorial Pacific by Fairbanks et al. (1992) [S i¿½ (d18Osw+8.77)/0.26] was applied, which has a similar slope as modelled by Delaygue et al. (2000) for the Southeast Pacific.
UK37 calibration to SST
Alkenone
Foraminifera, often living deeper in the water column, may record thermocline temperatures, which are set by ventilation during the winter months.
Mg/Ca calibration to SST
The d18Osw is extracted by means of the Mg/Ca-based SST estimate with analyzed d18O and temperature d18Ocalcite- d18Osw relationship. d18Osw is related linearly to salinity.
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Mg/Ca calibration to SST
As in Pahnke et al., 2007, Paleoceanography: ""in areas of strong contrast between the d D value of precipitation and seawater, and high amounts of rainfall (e.g., in the tropics close to river deltas), any changes in alkenone d D values caused by species or growth rate variations are likely to be secondary to the first order effects caused by freshwater fluxes."
Planktonic foraminifera ?18O values show no significant variability, indicating no major variations in SST and SSS during the past 3.2 kyrs
A companion reconstruction of d18O of sea water?a sea surface salinity and hydrology indicator?indicates a tight coupling with the East Asian monsoon system and remote control of IPWP hydrology on centennial?millennial timescales, rather than a dominant influence from local SST variation.
Mg/Ca calibration to SST
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we recall that the ?18O of foraminiferal calcite reflects changes not only in sea surface temperatures (SSTs) but also in sea-water isotopic composition.
Mg/Ca calibration to SST
Mg/Ca calibration to SST
Seawater ?18O (?18Ow in ? vs. V-SMOW) was estimated from Mg/Ca-derived calcification temperatures and ?18O of foraminiferal calcite (?18Oc in ? vs. PDB) by rearranging the isotopic paleotemperature equation of Shackleton (1974) (T = 16.9 ? 4 i¿½ (?18Oc ? ?18Ow)) and solving for ?18Ow. A V-SMOW vs. V-PDB correction of ?0.20? was applied, consistent with the correction factor common at time of publication of the Shackleton equation (see Bemis et al., 1998). Based on an analytical error of i¿½0.06? for ?18Oc and a combined analytical and calibration error of i¿½1 i¿½C for T (Mg/Ca), the uncertainty for reconstructed ?18Ow is estimated as i¿½0.26?.
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more depleted d Dwax  values in our paleorecord indicate an invigorated regional hydrological cycle, essentially a stronger Indonesian monsoon (IM), and conversely enriched d Dwax  values suggest reduced hydrologic intensity and a weak IM.
Mg/Ca calibration to SST
the ?sw can be directly converted to salinity using a relationship developed for the western tropical Pacific (Morimoto et al., 2002)
the ?sw can be directly converted to salinity using a relationship developed for the western tropical Pacific (Morimoto et al., 2002)
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Mg/Ca?based SST estimates are often subtracted from d18Oc to yield estimates of seawater d18O (d18Osw) [e.g., Lund and Curry, 2006; Richey et al., 2007].
Mg/Ca?based SST estimates are often subtracted from d18Oc to yield estimates of seawater d18O (d18Osw) [e.g., Lund and Curry, 2006; Richey et al., 2007].
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very cold subpolar waters in sediments
G. inflata as associated to the wintertime eastern branch of the Azores Current
N. pachyderma var. dextral as a winter deep-dwelling species linked with the Portugal Current
surface sediment spatial distribution of species unveils G. bulloides as the coastal upwelling species
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salinity/d18Ow influence thought to be minor
alkenone calibration to SST
The Mg/Ca temperature record has been used to extract the temperature effect of the d18O from G. bulloides to obtain the sea water d18O (d18Osw), which is associated with salinity and thus becomes a proxy for sea surface salinity (SSS).
The Mg/Ca temperature record has been used to extract the temperature effect of the d18O from G. bulloides to obtain the sea water d18O (d18Osw), which is associated with salinity and thus becomes a proxy for sea surface salinity (SSS).
The ?18O composition of foraminifera records both the oxygen isotopic composition of seawater (?18Oseawater) and the calcification temperature (through the kinetic fractionation effect) [Emiliani, 1955]. Shell ?18O and Mg/Ca calcification temperature values for G. ruber are substituted into the oxygen isotope paleotemperature equation [Shackleton, 1974] to solve the ?18Oseawater.
Mg/Ca calibration to SST (G. ruber white)
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Mg/Ca calibration to SST
Mg/Ca calibration to SST
Following Lea et al. (2000), the Mg/Ca-based temperature and ?18Ocalcite were used to calculate ?18Osw estimates.
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Thus by comparison of sea surface changes during the past several decades, it is reasonable to interpret the foraminiferal isotopic data mostly in terms of SST change.
Thus by comparison of sea surface changes during the past several decades, it is reasonable to interpret the foraminiferal isotopic data mostly in terms of SST change.
N. dutertrei d18O as indicator of conditions near the base of the local thermocline
G. ruber white d18O as monitor of annual average conditions in the near surface (see abstract)
G. ruber pink d18O as monitor of summer-fall nonupwelling season conditions
G. bulloides d18O (see abstract): sea surface conditions during the winter-spring upwelling season
Basically, the oxygen isotope record represents the glacial- interglacial eustatic sea level change. This change is superimposed by small-scale variations of the freshwater influence by precipitation and runoff, i.e., +0.2960 for the glacial and deglaciation and reaching as high as +0.796o in the Holocene.
The unsmoothed I´18Oshell time series exhibits a relatively strong, negative relationship with the annual AMO index (ra€‰=a€‰aˆ’0.55; adjusted pa€‰<a€‰0.001; Januarya€“December) over 113 yr (1900a€“2012).
dDn-C26 data unambiguously if perhaps qualitatively reflect changes in precipitation despite potentially confounding influences of vegetation type and other factors. "The dD values of the fatty acids from land-plant sources (n-C26, n-C28, n-C30) were significantly correlated to one another in each site"
dDn-C26 data unambiguously if perhaps qualitatively reflect changes in precipitation despite potentially confounding influences of vegetation type and other factors. "The dD values of the fatty acids from land-plant sources (n-C26, n-C28, n-C30) were significantly correlated to one another in each site"
dDn-C26 data unambiguously if perhaps qualitatively reflect changes in precipitation despite potentially confounding influences of vegetation type and other factors. "The dD values of the fatty acids from land-plant sources (n-C26, n-C28, n-C30) were significantly correlated to one another in each site"
dDn-C26 data unambiguously if perhaps qualitatively reflect changes in precipitation despite potentially confounding influences of vegetation type and other factors. "The dD values of the fatty acids from land-plant sources (n-C26, n-C28, n-C30) were significantly correlated to one another in each site"
dDn-C26 data unambiguously if perhaps qualitatively reflect changes in precipitation despite potentially confounding influences of vegetation type and other factors. "The dD values of the fatty acids from land-plant sources (n-C26, n-C28, n-C30) were significantly correlated to one another in each site"
dDn-C26 data unambiguously if perhaps qualitatively reflect changes in precipitation despite potentially confounding influences of vegetation type and other factors. "The dD values of the fatty acids from land-plant sources (n-C26, n-C28, n-C30) were significantly correlated to one another in each site"
dDn-C26 data unambiguously if perhaps qualitatively reflect changes in precipitation despite potentially confounding influences of vegetation type and other factors. "The dD values of the fatty acids from land-plant sources (n-C26, n-C28, n-C30) were significantly correlated to one another in each site"
dDn-C26 data unambiguously if perhaps qualitatively reflect changes in precipitation despite potentially confounding influences of vegetation type and other factors. "The dD values of the fatty acids from land-plant sources (n-C26, n-C28, n-C30) were significantly correlated to one another in each site"
The association of minimum d18O values in speleothems with high cave water stands indicative of increased rainfall on land, and the coincidence of the corresponding low d18O G. ruber values with sapropel events indicative of enhanced rainfall above the Mediterranean Sea, demonstrate that both land and sea systems simultaneously experienced enhanced rainfall during these events
known effects of photosynthesis pathways used by plants on the d13C of soil CO2 and of evaporation on soil water d18O
known effects of photosynthesis pathways used by plants on the d13C of soil CO2 and of evaporation on soil water d18O
Interpretations of changes in precipitation d18O have focused on (i) the correlation be- tween mean annual temperature and  18O of modern meteoric precipitation [for temperatures  10i¿½C (15)] and (ii) the anticorrelation between rainfall amount and precipitation d18O [the ?amount effect? (15)]. However, modern precipitation d18O trends basically result from the progressive removal of water vapor from air masses as they move from moisture source regions, resulting in decreasing water vapor and precipitation d18O, which explains the first-order observation of lower precipitation d18O values at higher lat- itudes. Precipitation d18O at Hulu/Dongge is therefore largely a measure of the fraction of water vapor removed from air masses be- tween the tropical Indo-Pacific and southeastern China.
Interpretations of changes in precipitation d18O have focused on (i) the correlation be- tween mean annual temperature and  18O of modern meteoric precipitation [for temperatures  10i¿½C (15)] and (ii) the anticorrelation between rainfall amount and precipitation d18O [the ?amount effect? (15)]. However, modern precipitation d18O trends basically result from the progressive removal of water vapor from air masses as they move from moisture source regions, resulting in decreasing water vapor and precipitation d18O, which explains the first-order observation of lower precipitation d18O values at higher lat- itudes. Precipitation d18O at Hulu/Dongge is therefore largely a measure of the fraction of water vapor removed from air masses be- tween the tropical Indo-Pacific and southeastern China.
Interpretations of changes in precipitation d18O have focused on (i) the correlation be- tween mean annual temperature and  18O of modern meteoric precipitation [for temperatures  10i¿½C (15)] and (ii) the anticorrelation between rainfall amount and precipitation d18O [the ?amount effect? (15)]. However, modern precipitation d18O trends basically result from the progressive removal of water vapor from air masses as they move from moisture source regions, resulting in decreasing water vapor and precipitation d18O, which explains the first-order observation of lower precipitation d18O values at higher lat- itudes. Precipitation d18O at Hulu/Dongge is therefore largely a measure of the fraction of water vapor removed from air masses be- tween the tropical Indo-Pacific and southeastern China.
the relationship between temperature and isotopic composition results from a mixing of different types of precipitation that varies with temperature.
The four diverse proxies attained extreme values ca. 4.1?3.8 ka, which corresponds to an interval of reduced moisture  reaching the cave interior."   "A simultaneous reduction in rainfall across the Mediterranean and the northern sector of the Middle East is actually consistent with a positive NAO phase (Cullen and deMenocal, 2000; Hurrell et al., 2003)."
observed negative correlation between summer monsoon rainfall amount and d18O
d18O values are comparatively stable which is interpreted to reflect stable temperature in the region.
The influence of vegetation changes and changes in the water residence time on d13C of DIC. Drier conditions cause an increase of C4 plants in the vegetation and longer residence times of water in the bedrock (increasing the contribution of bedrock carbonate to DIC). Either one would cause an increase of d13C in the speleothem. Temperature changes may have a similar effect on d13C as would changes  in the rainfall amount but would also affect d18O. Since d18O values are stable a temperature effect therefore can be eliminated.
d18O values are comparatively stable which is interpreted to reflect stable temperature in the region.
The influence of vegetation changes and changes in the water residence time on d13C of DIC. Drier conditions cause an increase of C4 plants in the vegetation and longer residence times of water in the bedrock (increasing the contribution of bedrock carbonate to DIC). Either one would cause an increase of d13C in the speleothem. Temperature changes may have a similar effect on d13C as would changes  in the rainfall amount but would also affect d18O. Since d18O values are stable a temperature effect therefore can be eliminated.
Based on previously published results from Oman and Yemen, we interpret the oxygen isotope ratios of stalagmite calcite to primarily reflect variations in the amount of rainfall (termed ??amount effect??; Dansgaard, 1964;Rozanski et al., 1992), with more negative d18O reflecting higher monsoon rainfall (Burns et al., 1998, 2001, 2003; Neff et al., 2001; detailed discussion in Fleitmann et al., 2004). This interpretation is substantiated by isotopic time series of tropical precipitation (Dansgaard, 1964; Rozanski et al., 1992; Johnson and Ingram, 2004) and paleoclimate records from the ASM domain (e.g., Wei and Gasse, 1999; Wang et al., 2001, 2005; Dykoski et al., 2005), which confirm the inverse relationship between d18O and the amount of precipitation in regions affected by monsoons
Low(high)Botuvera? speleothem d18O indicates intensified (weakened) SASM activity, more (less) Amazon moisture contribution and higher (lower) rainfall in southern Brazil.
Secondary controls can, however, be removed from the d18O record by comparing d18O from two stalagmites growing along the same atmospheric moisture transport pathway. As long as both stalagmites grew without kinetic or evaporative modification of their d18O signals, then the difference between d18O at the two sites only reflects loss of moisture from the atmosphere by rainfall as the air travels between them. The magnitude of the difference in d18O between the two sites reflects the amount of rain removed.
Both Sr/Ca and d13C show correlated values
The correlation coefficient between calcite ?18O and annual precipitation is r = -0.64 (n = 48, Figure S4). This anti- correlation on multi-decadal to interannual timescales is consistent with previous observations on orbital and millennial timescales from Wanxiang Cave (S4) and Hulu and Dongge Caves (S1, S2).
This isotopic difference is related primarily to the stronger convergence and uplift of water vapour over the southern Indonesian maritime continent during austral summer.
This isotopic difference is related primarily to the stronger convergence and uplift of water vapour over the southern Indonesian maritime continent during austral summer.
modern regional isotope-rainfall amount effect of 0.8% to 0.4%
modern regional isotope-rainfall amount effect of 0.8% to 0.4%
more positive values of d18O are interpreted to reflect less rainfall throughout the "amount effect"
more positive values of d18O are interpreted to reflect less rainfall throughout the "amount effect"
more positive values of d18O are interpreted to reflect less rainfall throughout the "amount effect"
Weighted mean annual ?18O value for the period from 1988?1996 was ?7.0?, with more neg- ative   in summer months (average ~ ?9.5?, SMOW) and more positive ?18O in winter months (average ~ ?4.5?, SMOW). Therefore, more negative ?18O values are consistent with a greater contribution of summer rainfall
observed seasonal changes of d18O of rainfall
observed seasonal changes of d18O of rainfall
observed seasonal changes of d18O of rainfall
A calibration between Chaac ?18O and the instrumental record of precipitation from a meteorological station in Mi¿½rida indicates a significant correlation between the two signals (r=?0.62, P=0.023) with a slope of ?176 mm??1 increase in Chaac ?18O (Fig. 4). The strength of the relationship between Chaac ?18O and rainfall amount is similar to that observed between rainfall amount data from adjacent meteorological stations (0.2brb0.7, Pb0.01).
this relationship is supported by the observed similarities with both regional and hemispheric temperature reconstructions available for the past 500 and 2000 years, respectively
Evident relationship of speleothem ?18O and temperature, which is generally positive (Williams et al. 2004, 2005, Whittaker 2008). It is probable that significant changes to d18Op would have resulted from perturbations in oceanic and atmospheric circulation patterns that altered the relative mix of vapour from subtropical and sub-Antarctic sources
observed cyclicity in the record and comparability with other pelaoclimate records which vary in phase with north Atlantic changes and ENSO
Annual and homogenized precipitation data of the nearby station Nauders, however, reveal good correspondence with observed C and O isotope changes on a decadal timescale, considering the age uncertainties and different temporal resolution
d18O in precipitation is primarily controlled by the amount effect over areas such as northern Minas Gerais, where precipitation is fundamentally the result of SAMS activity
d18O in precipitation is primarily controlled by the amount effect over areas such as northern Minas Gerais, where precipitation is fundamentally the result of SAMS activity
more positive values of d18O are interpreted to reflect less rainfall throughout the "amount effect"
observed correlation between rainfall d18O and temperature; commonly found relationship of d13C with cave hydrology and biomass above the cave
commonly found relationship of d13C with cave hydrology and biomass above the cave
Spannagel ?18O records and growth phases are in agreement with the ?18O pattern in Greenland ice cores on millennial to orbital timescales (Spi¿½tl and  Mangini, 2007 Spi¿½tl et al., 2006), with sediment proxies and growth of deep-sea corals from the North Atlantic (Frank et al., 2009; Mangini et al., 2005) and with other stalagmites from central Europe (Mangini et al., 2007). Trouet et al. (2009) found and discussed similarities of Spannagel speleothem ?18O values in  relation to their NAO reconstruction for the past 1000 yr based on speleothem data from Scotland (Proctor et al., 2000) and tree-ring data from Morocco (Esper et al., 2007). In addition, the super-regional character of our alpine location was explicitly demonstrated in a proxy intercomparison study investigating teleconnections between the tropical Pacific and mid-latitude regions (Graham et al., 2007).
1 year record of weekly monitoring of rainfall d18O near the cave
(1) The most recent stalagmite ?18O values are anticorrelated with Basin of Mexico precipitation, showing our record to be a robust proxy for rainfall amount. (2) Smothed ?18O data and Tacubaya wet season (May through November, MJJASON, comprising 95% of the annual total) rainfall (1880?2010 CE) is strongly anticorrelated. (3) Observational studies of tropical rainfall
Given that the precipitation regime in the study area is quite similar to the one at Brasilia station it is rea- sonable to assume that most of the isotopic fractionation is primarily related to total rainfall amount, which is charac- terized by more negative values during the wet season and more positive ones during the dry season.
the thickness of the laminae decrease during periods of drought
Analysis of modern rainfall d18O at Liang Luar shows that summer monsoon rainwater is depleted in 18O by 6?7% compared with rain water for the remainder of the year.This large isotopic contrast means that changes in the amount of summer rainfall, or the fraction of the year dominated by the northwest monsoon, produce a significant shift in the d18O of Flores rainfall. Today, the position of the ITCZ governs the balance between summer monsoon rain and winter trade wind induced orographic rainfall, and hence d18O at Flores. Water isotope-enabled climate models show that similar relationships between ITCZ positioning and rainfall d18O also prevailed at Flores during the last glacial. Millennial-scale changes in warm pool temperatures (and surface air temperature) were small over the last 23 kyr, thus changes in the d18O of rainfall, rather than temperature, dominate the record
Analysis of modern rainfall d18O at Liang Luar shows that summer monsoon rainwater is depleted in 18O by 6?7% compared with rain water for the remainder of the year.This large isotopic contrast means that changes in the amount of summer rainfall, or the fraction of the year dominated by the northwest monsoon, produce a significant shift in the d18O of Flores rainfall. Today, the position of the ITCZ governs the balance between summer monsoon rain and winter trade wind induced orographic rainfall, and hence d18O at Flores. Water isotope-enabled climate models show that similar relationships between ITCZ positioning and rainfall d18O also prevailed at Flores during the last glacial. Millennial-scale changes in warm pool temperatures (and surface air temperature) were small over the last 23 kyr, thus changes in the d18O of rainfall, rather than temperature, dominate the record
Analysis of modern rainfall d18O at Liang Luar shows that summer monsoon rainwater is depleted in 18O by 6?7% compared with rain water for the remainder of the year.This large isotopic contrast means that changes in the amount of summer rainfall, or the fraction of the year dominated by the northwest monsoon, produce a significant shift in the d18O of Flores rainfall. Today, the position of the ITCZ governs the balance between summer monsoon rain and winter trade wind induced orographic rainfall, and hence d18O at Flores. Water isotope-enabled climate models show that similar relationships between ITCZ positioning and rainfall d18O also prevailed at Flores during the last glacial. Millennial-scale changes in warm pool temperatures (and surface air temperature) were small over the last 23 kyr, thus changes in the d18O of rainfall, rather than temperature, dominate the record
Analysis of modern rainfall d18O at Liang Luar shows that summer monsoon rainwater is depleted in 18O by 6?7% compared with rain water for the remainder of the year.This large isotopic contrast means that changes in the amount of summer rainfall, or the fraction of the year dominated by the northwest monsoon, produce a significant shift in the d18O of Flores rainfall. Today, the position of the ITCZ governs the balance between summer monsoon rain and winter trade wind induced orographic rainfall, and hence d18O at Flores. Water isotope-enabled climate models show that similar relationships between ITCZ positioning and rainfall d18O also prevailed at Flores during the last glacial. Millennial-scale changes in warm pool temperatures (and surface air temperature) were small over the last 23 kyr, thus changes in the d18O of rainfall, rather than temperature, dominate the record
Analysis of modern rainfall d18O at Liang Luar shows that summer monsoon rainwater is depleted in 18O by 6?7% compared with rain water for the remainder of the year.This large isotopic contrast means that changes in the amount of summer rainfall, or the fraction of the year dominated by the northwest monsoon, produce a significant shift in the d18O of Flores rainfall. Today, the position of the ITCZ governs the balance between summer monsoon rain and winter trade wind induced orographic rainfall, and hence d18O at Flores. Water isotope-enabled climate models show that similar relationships between ITCZ positioning and rainfall d18O also prevailed at Flores during the last glacial. Millennial-scale changes in warm pool temperatures (and surface air temperature) were small over the last 23 kyr, thus changes in the d18O of rainfall, rather than temperature, dominate the record
Analysis of modern rainfall d18O at Liang Luar shows that summer monsoon rainwater is depleted in 18O by 6?7% compared with rain water for the remainder of the year.This large isotopic contrast means that changes in the amount of summer rainfall, or the fraction of the year dominated by the northwest monsoon, produce a significant shift in the d18O of Flores rainfall. Today, the position of the ITCZ governs the balance between summer monsoon rain and winter trade wind induced orographic rainfall, and hence d18O at Flores. Water isotope-enabled climate models show that similar relationships between ITCZ positioning and rainfall d18O also prevailed at Flores during the last glacial. Millennial-scale changes in warm pool temperatures (and surface air temperature) were small over the last 23 kyr, thus changes in the d18O of rainfall, rather than temperature, dominate the record
Moreover, the d18O of precipitation has been shown to be inversely correlated with the amount of rainfall, a relationship dubbed as the amount effect, with a slope between 0.4 and 0.8% per 100 mm increase in the mean annual precipitation
Thus, the isotopic composition of rainfall in the Andes integrates the effects of rainout of the heavy isotope along the moisture transport pathway.
Thus, the isotopic composition of rainfall in the Andes integrates the effects of rainout of the heavy isotope along the moisture transport pathway.
The study area receives moisture from Caribbean easterly waves guided by the trade winds, tropical cyclones from the eastern Pacific and Gulf of Mexico, and Caribbean moisture that traverses the isthmus of Tehuantepec to reach southwestern Mexico via recurved trade winds over the eastern tropical Pacific. The NAM extends from southern Mexico into the southwestern United States, and is an important contributor to annual rainfall  totals due to abundant summertime convection. Our study area is dominated by a summer moisture source (supplying ?97% of annual rainfall) from the surrounding tropical oceans.
Regression between rainfall amount and stalagmite d18O. "We choose to use 10- year decadal means to compare mean stalagmite ?18O and rainfall amount between wet and dry periods (i.e. different PDV phases) (Figure S8). Dating errors preclude us from using a regression between stalagmite ?18O and rainfall amount yearly data during the instrumental era. The slope of the regression yields a conversion of 1? stalagmite ?18O per 1.4 m/wet season (R2 = 0.74); an inverse correlation known as the ?Amount Effect? (Dansgaard, 1964; Rozanski et al., 1993)."
more positive values of d18O are interpreted to reflect less rainfall throughout the "amount effect" and the fact that during dry years, the water in the soil (due to evapotranspiration) has more positive d18O values. More positive d13C indicates decreased biological activity in the overlying soil during drier conditions
this interpretation is based on the correlation with instrumental temperatures (last 100 years) and in the good correlation with other nearby temperature record (SST inferred from Ifaty-4 coral d18O)
Still, the amount effect does not explain the total variance in the iso- topic composition of precipitation (R2 = 0.3, p < 0.01)
The amount of rainfall can be viewed as an indicator of the monsoon strength since the active period of the summer monsoon closely coincides with the rainy season in China. d18O in the speleothem reflects the amount of rainfall at short time scales (less than 10 years) but temperature trends (at larger time scales)
We conclude that, together with variations in seawater d18O, the pH effect on d18O of carbonates can obscure the temperature signal in the sponge d18O record sufficiently to explain the divergent trends of the Sr/Ca and the oxygen isotope records. These results indicate that for temperature reconstructions using C. nicholsoni skeletons, Sr/Ca is a more robust proxy than d18O.
d18O calibration to T assuming constant d18Ow
lower limit of 95% ci of difference in Sr/Ca between -20 and -125m, divided by difference in observed T at those depths.
lower limit of 95% ci of difference in Sr/Ca between -20 and -125m, divided by difference in observed T at those depths.
we find secular salinity increases of 0.35 A± 0.34 psu in Exuma Sound and 0.5 A± 0.35 psu in TOTO that must happen coevally with the secular temperature increases to explain the discrepancies between Sr/Ca and d18Oaragonite linear temperature trends. It is evident from (4) that our reconstruction is sensitive to the gradient d18Osw/S (0.54 %psu1). Despite the significant cumulative residual error from equations (1)a€“(3) (auxiliary material), our data clearly identify salinity variation in the subsurface waters of both Exuma Sound and TOTO during the last 100 years.
we find secular salinity increases of 0.35 A± 0.34 psu in Exuma Sound and 0.5 A± 0.35 psu in TOTO that must happen coevally with the secular temperature increases to explain the discrepancies between Sr/Ca and d18Oaragonite linear temperature trends. It is evident from (4) that our reconstruction is sensitive to the gradient d18Osw/S (0.54 %psu1). Despite the significant cumulative residual error from equations (1)a€“(3) (auxiliary material), our data clearly identify salinity variation in the subsurface waters of both Exuma Sound and TOTO during the last 100 years.
The range of the observed 18O cyclicity, 3a€“5a€°, is approximately equal to the annual range of observed rainfall d18O values (IAEA/WMO, 2003) for stations from Honduras, Costa Rica and Panama.
The negative relationship between precipitation totoals and tree-ring d18O is strengthened through complex effects of varying humidity on plant physiology. Simplified, moist atmospheric conditions will reduce transpiration and therefore reduce 18O water enrichment in needles.
Early-millennium climate was marked by relatively warm winters and high growth season relative humidity, especially ~AD 1100a€“1250, followed by the onset of cooler and drier conditions in the early 1500s. Winter temperatures apparently attained 20th century levels by about AD 1800, while relatively low growth season humidity persisted until
about AD 1900.
The I´18O of cellulose in cloud forest trees reflects the seasonal change in the I´18O of source water as determined by the amount of rainfall and the 18O-enrichment of cloud water.
A multi-proxy record spanning 180 years from Cedrela spp. showed a significant negative relationship between d18O in tree-ring cellulose and January precipitation.
A multi-proxy record spanning 180 years from Cedrela spp. showed a significant negative relationship between cellulose d18O and January precipitation.
A 150-year record obtained from Polylepis spp. showed a significant negative relationship between d18O and March precipitation
A 150-year record obtained from Polylepis spp. also showed a significant negative relationship between d18O and March precipitation
When the total rainfall is more, ..., trees continue to grow until a period of lower relative humidity (65%) leading to higher teak 18O.
When the total rainfall is more, ..., trees continue to grow until a period of lower relative humidity (65%) leading to higher teak 18O.
(i) the presence of relatively stronger amount effect in rainfall over a longer time scale, (ii) higher contribution of rainfall during the north-east (NE) monsoon, depleted in 18O, and (iii) relatively lesser   effect of the relative humidity in deciding tree 18O.
Instrumental calibration. A negative correlation between I´18O of precipitation and the amount of precipitation is observed in tropical regions including the Himalaya, which is termed as the a€˜amount effecta€™ (AraguA¡s-AraguA¡s et al., 1998; Dansgaard, 1964; Yadava and Ramesh, 2005).
correlation with instrumental data
In the monsoon season, high temperature usually indicates less rainfall and low relative humidity, which can make the tree-ring cellulose d18O heavier. Low PDSI indicates a dry condition.
In the monsoon season, high temperature usually indicates less rainfall and low relative humidity, which can make the tree-ring cellulose d18O heavier. Low PDSI indicates a dry condition.
In the monsoon season, high temperature usually indicates less rainfall and low relative humidity, which can make the tree-ring cellulose d18O heavier. Low PDSI indicates a dry condition.
In the monsoon season, high temperature usually indicates less rainfall and low relative humidity, which can make the tree-ring cellulose d18O heavier. Low PDSI indicates a dry condition.
In the monsoon season, high temperature usually indicates less rainfall and low relative humidity, which can make the tree-ring cellulose d18O heavier. Low PDSI indicates a dry condition.
In the monsoon season, high temperature usually indicates less rainfall and low relative humidity, which can make the tree-ring cellulose d18O heavier. Low PDSI indicates a dry condition.
In the monsoon season, high temperature usually indicates less rainfall and low relative humidity, which can make the tree-ring cellulose d18O heavier. Low PDSI indicates a dry condition.
As recorded in the meteorological data from the monsoon season, higher temperatures usually correlate with lower precipitation, and relative humidity levels, both of which lead to enriched d18O in tree rings?..moreover, as climate parameters are significantly correlated with one another, it is difficult to identify a dominant factor...Although the mechanisms underlying variations in tree ring d18O can generally be attributed to d18O of source water and evaporative enrichment of leaf water d18O, in pluvial monsoon regions these effects seem to be well represented by the PDSI,
As recorded in the meteorological data from the monsoon season, higher temperatures usually correlate with lower precipitation, and relative humidity levels, both of which lead to enriched d18O in tree rings?..moreover, as climate parameters are significantly correlated with one another, it is difficult to identify a dominant factor...Although the mechanisms underlying variations in tree ring d18O can generally be attributed to d18O of source water and evaporative enrichment of leaf water d18O, in pluvial monsoon regions these effects seem to be well represented by the PDSI,
As recorded in the meteorological data from the monsoon season, higher temperatures usually correlate with lower precipitation, and relative humidity levels, both of which lead to enriched d18O in tree rings?..moreover, as climate parameters are significantly correlated with one another, it is difficult to identify a dominant factor...Although the mechanisms underlying variations in tree ring d18O can generally be attributed to d18O of source water and evaporative enrichment of leaf water d18O, in pluvial monsoon regions these effects seem to be well represented by the PDSI,
As recorded in the meteorological data from the monsoon season, higher temperatures usually correlate with lower precipitation, and relative humidity levels, both of which lead to enriched d18O in tree rings?..moreover, as climate parameters are significantly correlated with one another, it is difficult to identify a dominant factor...Although the mechanisms underlying variations in tree ring d18O can generally be attributed to d18O of source water and evaporative enrichment of leaf water d18O, in pluvial monsoon regions these effects seem to be well represented by the PDSI,
As recorded in the meteorological data from the monsoon season, higher temperatures usually correlate with lower precipitation, and relative humidity levels, both of which lead to enriched d18O in tree rings?..moreover, as climate parameters are significantly correlated with one another, it is difficult to identify a dominant factor...Although the mechanisms underlying variations in tree ring d18O can generally be attributed to d18O of source water and evaporative enrichment of leaf water d18O, in pluvial monsoon regions these effects seem to be well represented by the PDSI,
As recorded in the meteorological data from the monsoon season, higher temperatures usually correlate with lower precipitation, and relative humidity levels, both of which lead to enriched d18O in tree rings?..moreover, as climate parameters are significantly correlated with one another, it is difficult to identify a dominant factor...Although the mechanisms underlying variations in tree ring d18O can generally be attributed to d18O of source water and evaporative enrichment of leaf water d18O, in pluvial monsoon regions these effects seem to be well represented by the PDSI,
As recorded in the meteorological data from the monsoon season, higher temperatures usually correlate with lower precipitation, and relative humidity levels, both of which lead to enriched d18O in tree rings?..moreover, as climate parameters are significantly correlated with one another, it is difficult to identify a dominant factor...Although the mechanisms underlying variations in tree ring d18O can generally be attributed to d18O of source water and evaporative enrichment of leaf water d18O, in pluvial monsoon regions these effects seem to be well represented by the PDSI,
Instrumental calibration. The I´18O value of precipitation is negatively correlated with the amount of precipitation at low latitudes, which is known as the a€œamount effecta€
calibration with instrumental climate data
March and July air temperature (r = 0.29; p < 0.01) are positively and significantly correlated to the oxygen isotopes for the period from 1929 to 2008. Oxygen isotopic values, which reflect the condensation temperature of the precipitation water showed increasing trends during 4111 to 3806 BC, indicating warm and dry period.
Significant Correlation with maximum June July Aaugust air temperature (r=0.54; p<0.001)
Significant Correlation with summer months of the England Wales Precipiation series (r = -0.58, n = 161, p < 0.001)
Significant Correlation with summer months of the England Wales Precipiation series (r= -0.39, n = 163, p<0.001)
The oldest part of the reconstruction is characterized by a prolonged period of relatively wet conditions
(1360a€“1450), followed by a period of drier conditions until 1600. Another wet period until 1760 follows, with
a short increase to relatively drier conditions around 1720. The most marked trend in the reconstruction is the shift to
dry conditions from 1760 to 1850. The late 20th century is characterized by increasingly dry summers, but these SPEI
values are not unprecedented in the record.
Wet conditions for large parts of the record prior to 1800, except two drier intervals in the 14th century and in the earlier half of the 16th century, and the late 20th century is characterized by increasing drought.
Calibration with instrumental rainfall record; More specifically, inverse correlations between the I´18O of precipitation and the amount of precipitation are observed at low latitudes, known as the a€˜amount effecta€™ (AraguA¡s-AraguA¡s et al., 1998; Dansgaard, 1964). Therefore, smaller amounts of precipitation are associated with higher I´18O values for precipitation, representing the enrichment of 18O in the source water that is taken up by the trees.
PDSI gives soil moisture status which in turn is related to precipitation and temperature
PDSI reflects the soil moisture stress which is an integrated effect of the precipitation and temperature