Processes Controlling the Mean Tropical Pacific Precipitation Pattern. Part I: The Andes and the Eastern Pacific ITCZ
Processes Controlling the Mean Tropical Pacific Precipitation Pattern. Part I: The Andes and the Eastern Pacific ITCZ
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DOI：
10.1175/jcli4198.1
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发表时间：
2007-07
影响因子：
4.9
通讯作者：
Ken Takahashi;D. Battisti
中科院分区：
文献类型：
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作者：
Ken Takahashi;D. Battisti
本文讨论了热带太平洋热带辐合带(ITCZ)一般位于赤道以北的问题。利用大气环流模式与海洋的理想化表示相结合的实验表明，安第斯山脉的存在足以通过蒸发降低南美洲西海岸的海表面温度，从而促进南北不对称，赤道以北的ITCZ因海洋和大气之间的相互作用而放大。蒸发冷却主要是低比湿空气下沉的结果，而低比湿空气下沉又是由于安第斯山脉对纬向平均气流的机械作用。低层云对海温的正反馈是影响上述机制效率的一个重要因素。在120°W以西，落基山脉和喜马拉雅山脉的存在产生了与安第斯山脉相当的作用力，但这不足以扭转或中和南北不对称…
Abstract The question of why the intertropical convergence zone (ITCZ) is generally north of the equator in the tropical Pacific is addressed. Experiments with an atmospheric general circulation model coupled to idealized representations of the ocean show that the presence of the Andes is enough to lower sea surface temperature (SST) off the west coast of South America through evaporation, thus promoting a north–south asymmetry, with the ITCZ north of the equator, which is amplified by interactions between the ocean and the atmosphere. The evaporative cooling results mainly from the subsidence of low specific humidity air, which is due in turn to the mechanical effect of the Andes on the zonal mean flow. The positive feedback from low-level clouds on SST is an important factor for the efficiency of the mechanism described. West of 120°W, the presence of the Rockies and Himalayas produces a comparable forcing to that of the Andes, but this is not enough to reverse or neutralize the north–south asymmetry se...