Tropical–extratropical climate interaction as revealed in idealized coupled climate model experiments

被引:12
|
作者
Haijun Yang
Zhengyu Liu
机构
[1] Peking University,Department of Atmospheric Science and Laboratory for Severe Storm and Flood Disasters, School of Physics
[2] University of Wisconsin-Madison,Center for Climatic Research and Department of the Atmospheric and Oceanic Sciences
来源
Climate Dynamics | 2005年 / 24卷
关键词
Hadley Cell; Atmospheric Bridge; Extratropical Climate; Oceanic Tunnel; Subsurface Temperature Change;
D O I
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中图分类号
学科分类号
摘要
Tropical–extratropical climate interactions are studied by idealized experiments with a prescribed 2°C SST anomaly at different latitude bands in a coupled climate model. Instead of focusing on intrinsic climate variability, this work investigates the mean climate adjustment to remote external forcing. The extratropical impact on tropical climate can be as strong as the tropical impact on extratropical climate, with the remote sea surface temperature (SST) response being about half the magnitude of the imposed SST change in the forcing region. The equatorward impact of extratropical climate is accomplished by both the atmospheric bridge and the oceanic tunnel. About two-thirds of the tropical SST change comes from the atmospheric bridge, while the remaining one-third comes from the oceanic tunnel. The equatorial SST increase is first driven by the reduced latent heat flux and the weakened poleward surface Ekman transport, and then enhanced by the decrease in subtropical cells’ strength and the equatorward subduction of warm anomalies. In contrast, the poleward impact of tropical climate is accomplished mainly by the atmospheric bridge, which is responsible for extratropical temperature changes in both the surface and subsurface. Sensitivity experiments also show the dominant role of the Southern Hemisphere oceans in the tropical climate change.
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页码:863 / 879
页数:16
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