HR: 0830h
AN: PP11A-0200    [PDF]
TI: Alkenone Temperature Record for the last 500 kyr in the Eastern Equatorial Pacific Ocean
AU: * Mendoza, A
EM: amendoza@cats.ucsc.edu
AU: Ravelo, C
EM: acr@cats.ucsc.edu
AB: The global climate system has varied much over geologic time with continuous oscillations between glacial (cool) and interglacial (warm) states. The focus of our work is on the Ocean Drilling Program (ODP) Site 847 ( 0o 11.593'N, 95o 19.227'W, water depth: 3334 m) located in the eastern equatorial Pacific Ocean west of the Galapagos Islands. Sea surface temperature at this site is influenced by the westward-flowing South Equatorial Current and equatorial divergent upwelling. Previous work has shown that the tropics may play a direct role in triggering changes in the global climate system. Changes in the solar energy budget due to orbital parameter changes have an influence on glacial/interglacial cycles, but paleorecords have shown that other processes and feedbacks in the atmosphere-ocean system play a large role as well. We use the alkenone proxy to reconstruct a high-resolution record (at 2000 years between samples) of past SST and compare it with other proxies ( „18O, CaCO3 accumulation, organic matter accumulation) to better understand the changes in climate and ocean conditions on sub-Milankovitch to Milankovitch timescales from 0-500 kyr in the eastern tropical Pacific. Over the last 500 kyr, SSTs have varied from 21.2 oC to 26.5 oC reflecting changes in climate related to the glacial/interglacial states. Glacial/interglacial cycles in the record occur with 100,000 year periodicity as seen in other records such as the benthic „18O record from ODP Site 846 ( 3o 5.696'S, 90o 49.078'W, water depth: 3295 m). Comparing the SST changes with measurements from other proxies helps to discriminate between changes in the upwelling conditions that affect productivity and changes in advection of water to this site. The ODP Site 847 SST and the „18O benthic record covary with each other indicating a strong teleconnection between climate changes across the globe. Some events in the „18O record are not observed in the alkenone record. Clearly there are cases when changes in ice volume occur independently from tropical temperature changes, although characterizing the circumstances under which high and low latitudes become independent from each other still needs further study. Further data analysis will need to be done to rigorously compare our SST record with other more distant records to have a better understanding of how the tropics affect changes in higher latitudes and global climate.
DE: 3344 Paleoclimatology
DE: 4267 Paleoceanography
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2003 Fall Meeting