2003年东亚夏季风活动的特点

利用2003年国家气象中心提供的再分析资料以及台站降水资料，诊断分析了2003我国东部地区汛期降水和东亚夏季风的活动特点，并对二者之间的联系进行讨论。结果表明：(1)2003年南海夏季风于5月第5候在南海南部建立。6月第1候全面爆发，比常年偏晚，南海夏季风强度也比常年偏弱；(2)该年夏季，副热带高压的一个显著特点是强度强、位置偏西，其中从6月下旬至7月中旬，副热带高压的位置稳定少变，其北脊线位25oN附近，且副高位置偏西，这导致了长江以南的犬部分地区高温少雨。这个阶段副热带高压西侧的南风气流将南海地区的水汽源源不断地输送到淮河流域，是淮河流域强降水过程水汽主要来源。

CHARACTERISTICS OF EAST ASIAN SUMMER MONSOON IN 2003

Characteristics of East Asian Monsoon and rainfall over eastern China in 2003 summer and their relationship had been discussed based on NMC (National Meteorological Center) reanalysis data and stations precipitation in 2003. Results showed that: 1) The southwest monsoon entered the South SCS (South China Sea) on the fifth pentad of May and it onset over all the SCS was on the first pentad of June 2003, which was later than normal year. Intensity of SCS summer monsoon was also weaker than normal. 2) Northwest Pacific Subtropical High (NPSH) was stronger than normal and extended westward remarkably in 2003 summer. Ridge of subtropical high steadily located nearby 25oN and extended westward during the period from the last dekad of June to middle dekad of July, leading to serious droughts in the South China. Southerly transported moisture from SCS to the Huaihe basin was main sources of the precipitation over this region while summer monsoon reached areas between the Yangtze and the Huaihe rivers.