Responses of Sea-Surface Temperature and Circulation to Global Climatic Change During the Past 200,000 Years in the Eastern Equatorial Atlantic Ocean
James V. Gardner, James D. Hays, 1976. "Responses of Sea-Surface Temperature and Circulation to Global Climatic Change During the Past 200,000 Years in the Eastern Equatorial Atlantic Ocean", Investigation of Late Quaternary Paleoceanography and Paleoclimatology, R. M. Cune, J. D. Hays
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Analyses of deep-sea cores from the equatorial Atlantic Ocean suggest strong variation in the intensity of atmospheric and oceanic circulation in response to the waxing and waning of ice sheets during the past 200,000 yr.
Comparisons of estimates of paleotemperature, determined by multivariate statistical analysis, between Holocene sediments and sediments from an 18,000 B.P. datum in an equatorial core show only small changes (1° to 2°C) for estimated temperatures for February, but changes of 2° to 10°C for temperature estimates for August. The average “annual” paleotemperatures for this equatorial core agree well with paleotemperatures calculated from oxygen isotope data.
By contrast, the zone of upwelling off northwest Africa shows almost a 10°C decrease in temperatures for February 18,000 B.P. but only a 1° to 4°C difference in August. The region between the equator and the upwelling zone shows very little change in sea-surface temperature for the past 200,000 yr.
Inferences drawn from estimates of paleotemperatures and faunal analyses suggest that during glacial stages the Intertropical Convergence Zone (ITCZ) was essentially in its interglacial position with seasonal migrations comparable to today's. The difference between glacial and interglacial modes is one of intensity. The glacial mode was more intense than the interglacial mode with the southeast and northeast trade winds strengthening seasonally during the winters of the Southern and Northern Hemisphere respectively.