摘要
利用一组高分辨率的卫星观测资料,研究了中尺度地形,特别是中南半岛长山山脉对南海夏季区域气候的影响。分析表明,当夏季暖湿、不稳定的西南季风接近长山山脉时,由于地形的强迫抬升作用在山脉的迎风一侧形成强降水区,而在山脉的背风一侧、南海西部则形成无降水区或降水量相对较少的区域。另外,盛行的西南季风气流绕过长山山脉的南端,在越南东南沿海明显形成一支边界层低空急流。这支低空急流通过其引起的蒸发冷却和沿岸上翻流在其北侧形成一片冷海水区,该冷水区的形成反过来又对其上的热带对流活动产生影响。研究还表明,南海中部夏季降水分布呈现东多、西少东西向分布不均匀特征,而降水这种东西向分布不均匀形成可能与中南半岛上中尺度地形的作用有关,严重低估中尺度地形的影响可能是造成全球大气环流模式模拟南海季风夏季降水时存在严重误差的主要原因。
The Tibetan Plateau, absorbing intense solar radiation, serves as a massive elevated heat source for the atmosphere, helping energize the summer monsoon. In the Asian monsoon domain, besides the Tibetan Plateau there are many less remarkable mountain ranges （-1.5 km in height）. Since they are narrow in width （500 km or less）, they are called mesoscale mountains to distinguish them from the massive Tibetan Plateau. While orographic lifting effect on rainfall is well known, the effect of mesoscale mountains on the Asian summer monsoon has rarely been discussed in the literature, because of inadequate observations. In this paper, a suite of high-resolution satellite measurements is used to investigate the effects of these mesoscale mountain ranges, especially the Annam Cordillera over the Indo-China Peninsula, on the summer monsoon of the South China Sea （SCS）.
The Satellite datasets used in this paper include： QuikSCAT surface wind velocity from August 1999 to August 2005 on a 0. 25°grid; Tropical Rain Measuring Mission （TRMM） SST on a 0. 25°grid and TRMM Precipitation Ra- dar （PR） surface rainfall on a 0. 5° grid, both from January 1998 to August 2005; Special Sensors Microwave Imager （SSM/I） rainfall and surface wind velocity from July 1987 to December 2004 on a 0. 25° grid. The monthly climatology is constructed by averaging over the available period for each dataset and the discussion in this paper is limited to these multi-year climatologies.
Annam Cordillera is a mountain range that rises above 500 m and runs in a south-north direction on the east coast of Indo-China Peninsula on the Vietnam-Laos/Cambodia borders. In summer, the QuikSCAT＇s summer wind climatology indicates that the southwesterly wind velocity reaches a maximum off the southeast coast of Vietnam. This coastal wind jet is also present in SSM/I product. As the southeasterly winds approach the mountain range, they are blocked by this mountain range. At the southern tip of this mountain range, on the other han
出处
《大气科学》
CSCD
北大核心
2007年第5期1021-1031,共11页
Chinese Journal of Atmospheric Sciences
基金
国家自然科学基金资助项目40575045
教育部留学回国人员科研启动基金
国家重点基础研究发展规划项目2004CB418304
关键词
中尺度地形
南海
夏季气候
卫星资料
mesocale mountains, the South China Sea, summer climate, high-resolution satellite observations
