华南前汛期降水异常年水汽输送特征分析

Water Vapor Transportation Characteristics in Pre-rainy Season Precipitation anomaly of South China

基于华南地区76个站点的逐日降水资料及NCEP再分析资料,采用拉格朗日方法的气流轨迹模式(HYSPLIT_4),分析了1980—2011年华南前汛期锋面降水和季风降水的水汽输送轨迹、主要源地及不同源地水汽贡献率。结果表明:锋面降水阶段气流轨迹主要有来自西北太平洋的东风气流、阿拉伯海-孟加拉湾的西风气流和欧亚大陆的西北冷空气。在锋面降水偏多年,西北太平洋的东风气流水汽输送贡献为69%,比偏少年多14%,阿拉伯海-孟加拉湾的西风气流输送贡献为20%,比偏少年少10%,此阶段受来自西北太平洋的水汽影响较大。季风降水阶段气流轨迹主要有来自北印度洋的越赤道气流、西北太平洋的东风气流和欧亚大陆的西北冷空气,在季风降水偏多年,来自北印度洋的越赤道水汽输送贡献为88%,比偏少年多18%,而西北太平洋的水汽输送贡献为7%,比偏少年少15%,此阶段受西南越赤道气流的水汽输送影响较大。

Based on NCEP reanalysis data and daily precipitation data of 76 meteorological stations in South China from 1980 to 2011,using Lagrangian trajectory model（ HYSPLIT_4）,the water vapor transportation path,main sources and its contribution in frontal rainfall and monsoon rainfall anomalies during pre-rainy season in South China were studied. Results showed that： In frontal rainfall phase,water vapor path was mainly from Western Pacific,Arabia sea-Bay of Bengal and Continental Eurasian. In wet years of frontal rainfall,water vapor from the Western Pacific accounted for more than 69%,and the water vapor was 14% higher than that in dry years. While the contribution of water vapor from Arabia sea—Bay of Bengal was 20%,and the water vapor was10% less than that in dry years. This stage was greatly influenced by the water vapor from the Pacific Northwest. In Monsoon rainfall phrase,water vapor was mainly from the cross-equatorial flowfrom north Indian Ocean,the Pacific Northwest wind airflowand the northwest cold air in Eurasia. In wet monsoon rainfall years,the water vapor from India ocean had the largest contribution 88%,the moisture from Indian ocean was 18% higher than that in dry years,while the moisture from the Western Pacific was 7%,the moisture from the Western Pacific was 15% less than that in dry years. This stage was greatly influenced by southwest cross-equatorial flowof water vapor transmission.