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On the effect of the land-ocean contrast to the monsoon circulation

陆海对比对季风环流的影响

基本信息

批准号：
02452058
负责人：
SUMI Akimasa
金额：
$ 3.39万
依托单位：
Center for Climate System Research, University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1991
项目状态：
已结题

项目摘要

Characteristics of the coupled land-ocean atmosphere system have been investigated by using numerical models. Numerical experiments have been designed and conducted in two different experimental set-up ; (1) an atmospheric model is used with assumed Sea Surface Temperature (SST), and (2) an ocean-atmosphere coupled model is used.Two extreme cases were investigated ; (1) the land surface is desert-like, where few evaporation is supplied, and (2) the land surface is swamp, where infinite moisture supply from land surface can be expected. In both cases, rectangular ocean, which extends from 90ﾟE to 270ﾟE between 60ﾟN and 60ﾟS,is assumed.Following conclusions were obtained ;(1) When the land surface is dry, thermal contrast between land and sea is strong (land surface temperature is higher than SST), and the heat low are generated over the land. Convection center is located to the east of the ocean, and the monsoon westerly is also located in the eastern part of the ocean. This feature is also confirmed in the couled model run, where SST tends to be zonally uniform.(2) When the land surface is wet, the thermal contrast between land and ocean is reverse (Tg SST) to the previous case. In this case, convection center and the monsoon westerly is located to the western part of the ocean. This feature is also confirmed in the coupled-model run, where the SST in the eastern part of the ocean tends to decrease due to the upwelling caused by a strong easterly.In summary, it is suggested that there exists characteristic flow regimes corresponding to the land-ocean heat contrast.It is also shown where the seasonal forcing is stron, there is no interaseasonal variation.

利用数值模式研究了海气耦合系统的特征。本文设计了两种不同的数值试验方案：（1）采用假定海表温度（SST）的大气模式，（2）采用海气耦合模式，并对两种极端情况进行了试验研究。（1）陆地表面是沙漠状的，其中很少有蒸发，以及（2）陆地表面是沼泽，在那里可以预期来自陆地表面的无限水分供应。在两种情况下，均假定海洋为矩形，在60 ° N和60 ° S之间，海洋的范围从90 ° E到270 ° E，得到以下结论：（1）当陆表干燥时，海陆热力对比强烈（陆表温度高于SST），在陆地上产生热低压;对流中心位于海洋东部，季风西风也位于海洋东部。这一特征在耦合模式运行中也得到了证实，其中SST趋于纬向均匀。(2)当陆面湿润时，陆面与海洋之间的热反差与前一种情况相反（Tg SST）。在这种情况下，对流中心和季风西风位于海洋的西部。在耦合模式中，由于强东风引起的上升流，东部海温有下降的趋势，这一特征也得到了证实。综上所述，存在着与海陆热反差相对应的特征流场。在季节强迫较强的地方，没有季节间变化。