“双峰”期孟加拉湾风暴对西南水汽输送的贡献

The Contribution of Storms over the Bay of Bengal to Southwest Water Vapor Transport during Double-Peak Periods

5月和10～11月是孟加拉湾风暴活动的两个“峰值”期,风暴对西南水汽输送有重要影响,本文利用2001～2010年10年的JTWC （Joint Typhoon Warning Centre）风暴资料和NCEP （National Centers for Environmental Prediction） /NCAR （National Center for Atmospheric Research）1°×1°再分析资料,研究风暴“双峰”期对西南水汽输送的贡献,结果表明：风暴水汽向北输送最强,其次是向东输送,其它方向的输送较弱;在风暴中心区域及西南水汽通道,各层和整层的通量均大于气候平均值,风暴的西南水汽输送特征显著;两个“峰值”期风暴的经向水汽输送比纬向几乎大一倍,5月“峰值”期孟加拉湾风暴在西南方向的实际水汽输送总量约是10～11月的2倍,孟加拉湾风暴前“峰值”期（5月）对水汽输送的影响大于后“峰值”期（10～11月）,孟加拉湾风暴是5月西南水汽输送的主要系统之一.

Storms of the Bay of Bengal have an important impact on southwest water vapor transportation, with double-peak periods （May and Oct-Nov） occurring in storm active stage. According to 2001-2010 JTWC （Joint Typhoon Warning Centre） storm data and NCEP （National Centers for Environmental Prediction）/NCAR （National Center for Atmospheric Research） 1° ×1° reanalysis data on southwest water vapor transportation in double-peak periods, the storm water vapor is transported most strongly northward, followed by eastward transportation. Transportation in other directions is weaker. In the center and southwestern areas of the storm, each layer of water flux and all layers combined are higher than the climate average value for the southwest. In the double-peak periods, storm meridional moisture transportation is double than that of zonal transport. The actual southwest water vapor transportatioia for storms in May is twice as large as that in Oct-Nov. The effect of water vapor transport prior to the peak period （May） for storms in the Bay of Bengal is greater than that after the peak period （Oct-Nov）. the Bay of Bengal storms are therefore one of the main systems for southwest water vapor transportation in May.