Mid-Brunhes strengthening of the Indian Ocean Dipole caused increased equatorial East African and decreased Australasian rainfall

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doi: 10.1029/2009GL042225
Author(s): Gupta, Anil K.; Sarkar, Sudipta; De, Soma; Clemens, Steven C.; Velu, Angamuthu
Author Affiliation(s): Primary:
Indian Institute of Technology, Department of Geology and Geophysics, Kharagpur, India
Brown University, United States
Volume Title: Geophysical Research Letters
Source: Geophysical Research Letters, 37(6). Publisher: American Geophysical Union, Washington, DC, United States. ISSN: 0094-8276 CODEN: GPRLAJ
Note: In English. 26 refs.; illus.
Summary: The tropical Indian Ocean is an important component of the largest warm pool, marked by changes in sea surface temperatures and depths of thermocline and mixed layer in its western and eastern extremities leading to the development of a dipole mode - the Indian Ocean Dipole (IOD). A narrow band of westerlies (7°N to 7°S) sweep the equatorial Indian Ocean during the April-May and October-November transitions between the summer- and winter-monsoon seasons. These Indian Ocean equatorial westerlies (IEW) are closely related to the IOD, intensifying the upper ocean Eastward Equatorial current also known as Wyrtki jets. The strength of the IOD/IEW determines the moisture content in East Africa. A major decrease in the strength of the IEW (strengthening or positive mode of the IOD) during the mid-Brunhes epoch (∼300-250 Kyr BP) coincides with a wetter equatorial East Africa, a drier Australasia and a stronger Indian summer monsoon, indicating that the IOD/IEW play a significant role in driving climate change in East Africa, Australasia and South Asia.
Year of Publication: 2010
Research Program: ODP Ocean Drilling Program
Key Words: 24 Surficial Geology, Quaternary Geology; Africa; Arabian Sea; Atmospheric circulation; Australasia; Brunhes Chron; Cenozoic; Climate change; Currents; East Africa; Equatorial region; Equatorial westerlies; Hydrology; Indian Ocean; Indian Ocean Dipole; Leg 115; Leg 117; ODP Site 716; ODP Site 723; Ocean Drilling Program; Ocean currents; Paleo-oceanography; Paleocirculation; Paleoclimatology; Paleocurrents; Quaternary; Rainfall; Tropical environment; Upper Quaternary; Winds; Wyrtki jets
Coordinates: N180304 N180305 E0573634 E0573633
N045600 N045600 E0731700 E0731700
Record ID: 2011002191
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