华南前汛期典型涝年低频降水特征及其与低频水汽输送的关系

利用1961—2013年国家气象信息中心提供的全国753站逐日降水资料、NCEP/NCAR逐日再分析风场和比湿资料，以及NOAA的HYSPLIT模式同期驱动资料，分析了华南前汛期9个典型涝年的低频降水特征及其与低频水汽输送的关系，探讨了低频水汽输送通道及源地。结果表明，华南前汛期9个典型涝年降水存在显著的10~20 d低频振荡周期，闽赣地区30~60 d低频周期也显著。华南前汛期850 hPa纬向、经向水汽通量都存在10~20 d的显著低频周期。影响华南前汛期典型涝年10~20 d低频降水的四个低频水汽输送通道及源地为:以马达加斯加岛北部印度洋、赤道中印度洋为参考源地的西南水汽通道；以日本群岛东南洋面和赤道中太平洋为源地的东南水汽通道；以里海北部和贝加尔湖东南侧为参考源地的西北冷空气通道；以白令海为参考源地的东北冷湿水汽通道。对广东佛冈站和江西广昌站的典型涝年进行水汽后向轨迹模拟验证了上述四个水汽通道，模拟源地均位于水汽通道关键区域。水汽信号参考源地和模拟源地，可作为华南前汛期提前2~6 d延伸期预报时重点考察地区。 

LOW-FREQUENCY RAINFALL CHARACTERISTICS OF THE TYPICAL FLOOD YEARS IN THE ANNUALLY FIRST RAINY SEASON OF SOUTH CHINA AND THEIR RELATIONSHIPS WITH LOW-FREQUENCY MOISTURE TRANSPORTATION

Based on 753-stations' daily rainfall data provided by the National Meteorological Information Center and the NCEP/NCAR daily reanalysis data from 1961—2013, and HYSPLIT model synchronous driving data from NOAA, the low-frequency variability of the precipitation of nine typical flood years and its relationships with moisture transport in the annually first rain season (AFRS) of South China is investigated, and the source regions and transportation paths of low-frequency water vapor are discussed. The results show that the precipitation of the nine typical flood years is mainly controlled by 10~20 d oscillation in the AFRS, and 30~60 d low frequency oscillation is also significant in the area connecting Jiangxi with Fujian. Both the longitudinal and zonal water vapor flux have remarkable 10~20 d low frequency oscillation in the AFRS. There are four 10~20 d water vapor reference sources and transportation paths which affect the 10~20d low frequency precipitation of the nine flood years in the AFRS. These sources lie in the part of the Indian Ocean north of Madagascar Island and equatorial middle India Ocean(the southeast moisture transport channel), the ocean to the southeast of Japanese archipelago and the equatorial middle Pacific(the southeast moisture transport channel), north of the Caspian Sea and southeast of Lake Baikal(the northwest cold air channel), and Bering Sea(the northeast cold moisture transport channel). The above four water vapor transportation paths are verified by the backward trajectory simulations of water vapor in typical flood years of the AFRS at Fogang and Guangchang stations respectively, and the simulation sources all lie in the key areas of the moisture transport channels. Both the reference and simulation sources can be taken as important areas to make extended-period(2~6 days ahead)prediction.