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A see‐saw oscillation between the Amazon and Congo basins
Author(s) -
Eltahir Elfatih A. B.,
Loux Brian,
Yamana Teresa K.,
Bomblies Arne
Publication year - 2004
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2004gl021160
Subject(s) - amazon rainforest , geology , oscillation (cell signaling) , amazon basin , climatology , geography , oceanography , ecology , genetics , biology
[1] The climate of Earth is shaped to a significant degree by the occurrence of intense storms over three regions: the Amazon and Congo basins and the Pacific Ocean. However, little is known about natural oscillations in the amounts of rainfall over the Amazon and Congo basins. Here, we present new satellite observations on tropical rainfall distribution and historical river flow observations to document a natural see-saw oscillation across the Atlantic Ocean: floods over the Amazon basin tend to coincide with droughts over the Congo basin and vice versa. This phenomenon is most significant during the southern hemisphere summer, and was observed most clearly during the decades of 1945– 1955, 1960s, and 1970s. The mechanism responsible for this see-saw phenomenon is based on the Gill model of tropical circulations since rising motions associated with floods over either of the two basins is likely to force subsidence and droughts over the other basin. [2] The large scale rising air motion near the Equator is associated with large scale convection and rainfall. This rising motion is not uniform in space or time and tends to concentrate over the Western Pacific Ocean, the Congo basin and the Amazon basin. This is best illustrated by Wyrtki [1982, Figure 3]. Together these three regions receive a large fraction of tropical rainfall. During the last few decades the variations in rainfall over the Pacific Ocean