Eastern Equatorial Pacific 30KYr Alkenone SST Reconstructions Dubois, N.; Kienast, M.; Normandeau, C.; Herbert, T.D. Dubois, N. Kienast, M. Normandeau, C. Herbert, T.D. Last Glacial Maximum Sea Surface Temperature Reconstruction earth science/paleoclimate/paleoceanography (alkenone unsaturation index Uk37 prime,null,null,dimensionless,null,paleoceanography,null,gas chromatography,N,null) earth science/paleoclimate/climate reconstructions|paleoceanography (age,null,null,calendar kiloyear before present,null,climate reconstructions|paleoceanography,null,null,N,null) earth science/paleoclimate/climate reconstructions|paleoceanography (depth,null,null,centimeter,null,climate reconstructions|paleoceanography,null,null,N,null) earth science/paleoclimate/climate reconstructions|paleoceanography (sea surface temperature,alkenone unsaturation index,null,degree Celsius,annual,climate reconstructions|paleoceanography,null,null,N,calibration data set: Prahl et al. 1998) earth science/paleoclimate/reconstructions (ME0005A-27JC>LATITUDE -1.8533>LONGITUDE -82.7867) (TR163-19P>LATITUDE 2.27>LONGITUDE -90.95) (ME0005A-43JC>LATITUDE 7.85583>LONGITUDE -83.60833) (TR163-22P>LATITUDE .515>LONGITUDE -92.3983) (TR163-31P>LATITUDE -3.62>LONGITUDE -83.97) We present new alkenone-based sea surface temperature (SST) estimates from the eastern equatorial Pacific (EEP) for the last 30 kyr. By combining these new results with recently published records from the region, we reconstruct the spatial pattern of changes in SST during the Last Glacial Maximum (LGM). Alkenone-based SST estimates show a greater glacial cooling in the upwelling environment of the cold tongue than in sites located further north in the equatorial front and eastern Pacific Warm Pool. This result agrees with the paradigm of stronger glacial winds, increased upwelling, steeper zonal thermocline tilt, and stronger advection of cold water in the Peru Current. Furthermore, we investigate possible changes in glacial surface hydrography by using the alkenone-based SST reconstructions to correct planktonic foraminifera d18O for the temperature effect. After additional correction for the global ice volume effect, the residual changes in seawater d18O show a clear latitudinal pattern that would be consistent with a southward shift of the Intertropical Convergence Zone. We thus suggest that changes in sea surface salinities could explain contrasting SST reconstructions based on planktonic foraminifera d18O, which implied a weakening of the cold tongue. The controversial LGM dynamics of the EEP reconstructed by different proxies, i.e., a weakening or a strengthening of the cold tongue, highlight the necessity to better assess the influence of various biases on these proxies. STUDY NOTES: Reconstructed alkenone-based sea surface temperature from five eastern equatorial Pacific sediment cores covering the last 30 kyr BP. Cores ME0005A-27JC, ME0005A-43JC and TR163-31P were analyzed for alkenone unsaturation at Dalhousie University following standard laboratory procedures detailed by Kienast et al. (2006), whereas cores TR163-19P and TR163-22P where analyzed at Brown University following similar laboratory procedures detailed by Herbert et al. (1998). The age models for these cores were adopted as published in earlier studies (ME0005A-27JC from Kienast et al. 2007, ME0005A-43JC from Benway et al. 2006, TR163-19P from Lea et al. 2000, TR163-22P from Lea et al. 2006, TR163-31P from Martin et al. 2002). The alkenone unsaturation index UK037 is calculated as UK'37 = (C37:2)/(C37:3 + C37:2), where (C37:2) and (C37:3) are concentrations of the diunsaturated and triunsaturated C37 methyl alkenones. For conversion into temperature estimates, we used the culture calibration of Prahl et al. (1988) (UK'37 = 0.034T + 0.039). Replicate analyses of selected samples indicate an analytical precision of about ±0.01 UK'37 units (0.3°C). NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Dubois, N. Investigator : Kienast, M. Investigator : Normandeau, C. Investigator : Herbert, T.D. 2011-09-26 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/12195 https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/dubois2009/dubois2009.xls https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/dubois2009/dubois2009.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/dubois2009/dubois2009.xls https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/dubois2009/dubois2009.txt English https://www.ncdc.noaa.gov/paleo/study/12195 https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/dubois2009/dubois2009.xls https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/dubois2009/dubois2009.txt Dubois, N., M. Kienast, C. Normandeau, and T.D. Herbert. 2009. Eastern equatorial Pacific cold tongue during the Last Glacial Maximum as seen from alkenone paleothermometry. Paleoceanography, 24, PA4207, doi:10.1029/2009PA001781. START YEAR: 29760 cal yr BP * END YEAR: 980 cal yr BP -92.3983 -3.62 -82.7867 7.85583