Author Posting. © American Geophysical Union, 2006. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Paleoceanography 21 (2006): PA3008, doi:10.1029/2005PA001208.
Multi-proxy geologic records of δ18O and Mg/Ca in fossil foraminifera from
sediments under the Eastern Pacific Warm Pool (EPWP) region west of Central America
document variations in upper ocean temperature, pycnocline strength, and salinity (i.e., net precipitation) over the past 30 ky. Although evident in the paleotemperature record,
there is no glacial-interglacial difference in paleosalinity, suggesting that tropical
hydrologic changes do not respond passively to high-latitude ice sheets and oceans.
Millennial variations in paleosalinity with amplitudes as high as ~4 PSU occur with a
dominant period of ~3-5 ky during the glacial/deglacial interval and ~1.0-1.5 ky during the Holocene. The amplitude of the EPWP paleosalinity changes greatly exceeds that of published Caribbean and western tropical Pacific paleosalinity records. EPWP
paleosalinity changes correspond to millennial-scale climate changes in the surface and
deep Atlantic and the high northern latitudes, with generally higher (lower) paleosalinity during cold (warm) events. In addition to Intertropical Convergence Zone (ITCZ) dynamics, which play an important role in tropical hydrologic variability, changes in Atlantic-Pacific moisture transport, which is closely linked to ITCZ dynamics, may also
contribute to hydrologic variations in the EPWP. Calculations of interbasin salinity
average and interbasin salinity contrast between the EPWP and the Caribbean help
differentiate long-term changes in mean ITCZ position and Atlantic-Pacific moisture
Support for this research was provided by the U.S. National Science Foundation.
Eastern tropical Pacific
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