摘要
本文利用2003年6～7月逐日NCEP/NCAR再分析资料分别计算了淮河流域梅雨期的水汽输送和该区域的水汽收支,分析了大尺度水汽输送和梅雨期降水之间的关系。结果表明:2003年梅雨期间(6月20日～7月23日)淮河流域水汽输送的来源主要有2个,一是孟加拉湾的西南气流经中南半岛北部进入华南再向淮河流域输送,二是来自西太平洋副热带高压南侧的偏东气流在南海转向形成的偏南气流进入华南再向北输送,以上两条输送带以定常方式向淮河流域输送水汽。通过计算梅雨期的整层涡动水汽输送,发现经向水汽输送非常稳定,纬向水汽输送具有较大幅度变化。研究还表明:2003年梅雨期间淮河流域的水汽收支主要来自经向水汽输送,特别是南部边界的水汽流入,而纬向水汽输送多表现为水汽的流出。梅雨期间淮河流域经向水汽收支的突然增强和维持稳定往往对应一次强降水过程的开始。梅雨期间淮河流域净水汽收入主要来源于经向从地面到600hPa高度的深厚水汽输送,另外在纬向近地面层还有一支弱的净水汽流入,而中低层为明显的纬向净水汽流出。在经向水汽净输入相当情况下,纬向水汽净输出的减弱有利于增强强降水过程的强度。淮河流域2003年夏季经向水汽收支的爆发性增长和突然减弱和该区域的入、出梅日期对应,它的演变反映了东亚夏季风由南向北推进的进程。
By calculating the daily atmospheric vapor transportation and analyzing the net vapor income over Huaihe river basin during the Meiyu period it was showed that the large scale vapor transportation plays an significant role in enhancing rainfall. It was also showed that there are two major sources of the vapor transportation. One of them is a southwest airflow which originally comes from Bangladesh Bay, and the other is a near south airflow which is converted from the east airflow in the south of the west pacific subtropical high system. It was found that the meridional component of the vapor transportation is always strong and steady during the Meiyu period, while its zonal component had large variations. It was the meridional component that contributed to the net vapor income mainly. The rainfall of this region always became more intense as it increased abruptly and maintained. In the meridional direction, there was a substantial depth layer (mainly from surface to 600 hPa) of vapor transportation that bought vapor in, but the airflow always took the vapor out in the reverse direction. And, the fluctuations of the net vapor income reflected the east Asia Monsoon's movement northward in summer.
出处
《气象科学》
CSCD
北大核心
2005年第3期265-271,共7页
Journal of the Meteorological Sciences
基金
安徽省人才开发资金(编号:20022037)资助
关键词
梅雨
水汽输送
水汽收支
MonsoonVapor transportationNet vapor income
