苗长明,丁一汇,郭品文,沈杭锋,樊高峰. 2015. 水汽输送与江南南部初夏雨季及降水变化的联系[J]. 气象学报, 73(1):72-83, doi:10.11676/qxxb2015.006
水汽输送与江南南部初夏雨季及降水变化的联系
Linkage of the water vapor transport distribution with the rainy season and its precipitation in the southern regions south of the Yangtze River during the early summer
投稿时间:2014-05-09  修订日期:2014-08-25
DOI:10.11676/qxxb2015.006
中文关键词:  初夏雨季  江南南部  降水  水汽通量  水汽通道
英文关键词:The early summer rainy season  The southern regions south of the Yangtze River  Precipitation  Water vapor flux  Water vapor transport channel
基金项目:浙江省社会发展项目(2009C33053)、中国工程院重大咨询项目“浙江沿海及海岛综合开发战略研究”气象子专题(2010ZD08)。
作者单位
苗长明 杭州市气象局, 杭州, 310051
南京信息工程大学气象灾害预报预警与评估协同创新中心, 南京, 210044 
丁一汇 国家气候中心, 北京, 100081 
郭品文 南京信息工程大学气象灾害预报预警与评估协同创新中心, 南京, 210044 
沈杭锋 杭州市气象局, 杭州, 310051 
樊高峰 浙江省气候中心, 杭州, 310002 
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中文摘要:
      基于1961—2010年美国国家环境预报中心/大气研究中心(NCEP/NCAR)的逐日再分析格点资料,分析了初夏水汽输送的分布和演变过程及其与中国江南南部初夏雨季的关系。结果显示,初夏水汽输送总体上随夏季风前沿自南向北加强,有3次水汽通量突然增大的涌先后从中国南海北传到25°N及其以南、25°—30°N、30°N及其以北地区,水汽涌和相应峰的发生时间分别对应华南前汛期、江南南部初夏雨季、长江流域梅雨的开始和结束时间。江南南部在初夏雨季处在水汽通量高值区的北缘、水汽辐合区内。青藏高原南侧水汽辐散区是影响江南南部初夏雨季的直接水汽源,澳大利亚北部到印度洋和阿拉伯海南部地区的大面积水汽辐散区则是间接水汽源。经向水汽输送演变对雨季起(讫)具有标志性意义,纬向水汽输送也不容忽视。雨季开始(结束)时江南南部地区的南界(北界)中低层水汽流入(流出)显著增大,但北界(南界)水汽通量并未同步发生显著变化;雨季期间的纬向水汽输送明显增强,水汽通量大于经向水汽输送。雨季强、弱具有年代际变化,且与纬向水汽流入的相关比经向水汽流入的相关更显著。影响江南南部初夏雨季的水汽输送路径主要有两条,北支是从孟加拉湾北部经缅甸和云南、贵州的水汽输送,南支是经孟加拉湾、中南半岛、中国南海与西太平洋副热带高压西侧水汽汇合的水汽输送。强雨季年孟加拉湾北部的东北向水汽输送和中国南海的北向水汽输送都增强,弱雨季年则相反。孟加拉湾、中国南海南部和西太平洋暖池区是显著的水汽辐合区,是江南南部初夏雨季的水汽输送通道而不是水汽源,水汽辐合越弱(强)越有利于(不利于)江南南部初夏雨季的降水,其影响机制可能在于通道上的对流活动对江南南部初夏雨季水汽输送具有拦截作用。
英文摘要:
      Based on the NCEP/NCAR reanalysis data from 1961 to 2010, the distribution and evolution of the water vapor transport and its linkage with the early summer rainy season in the southern regions south of the Yangtze River have been studied. The findings are as follows. The water vapor transport increases and moves from south to north along with the summer monsoon front, there are 3 surges of the water vapor flux increasing abruptly at the South China Sea and extending northward to the south of 25°N, 25°-30°N and the north of 30°N successively, and the surges and relevant peaks arising correspond with the beginnings and ends of the pre-flood season in South China, the early summer rainy season in the southern regions south of the Yangtze River, and the Meiyu in the Yangtze-Huaihe River basin, respectively. During the early summer rainy season, the southern regions south of the Yangtze River lie in the north border of the high water vapor flux region, and there is a convergence belt over there. Additionally, the divergence field in the southern side of the Tibetan Plateau is the direct source of water vapor for this rainy season, and the divergence fields at the the areas of northern Australia to Indian Ocean and southern Arab Sea are indirect ones. The meridional water vapor transmission plays a major role for the beginning/end of the early summer rainy season, as the water vapor inflows are impulsively enhanced over the south (north) boundary of these regions on the start (last) day. But the zonal water vapor transmission should not be neglected as well, for the water vapor flux over the west boundary is much greater than that over the south boundary. The intensity indexes of the rainy season have inter-decadal climate variability, and correlate stronger with the anomaly of the total water vapor flux over the west than the south boundary. There are 2 main water vapor transfer paths to the southern regions south of the Yangtze River, one is the north branch, from the north of the Bay of Bengal passing over Burma, Yunnan and Guizhou, the other is the south branch, from the Bay of Bengal passing over the Indo-China peninsula and the South China Sea, and afterwards combined with the water vapor from the west of the Western Pacific subtropical high. Both of the transmissions following the paths mentioned above are enhanced (reduced) for heavy (weak) early summer rainy seasons. The Bay of Bengal, the south of the South China Sea, and the Western Pacific warm pool at the east of the Philippines, which are significant convergence fields, all play the roles of channels rather than the sources of the water vapor transport of the early summer rainy season, and the weak (strong) convergence over there is advantageous (disadvantageous) for the precipitation in the southern regions south of the Yangtze River. The mechanism may be attributable to the convection over the channels that could intercepts the water vapor transport over there.
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