摘要:利用1951~2015年NCEP/NCAR再分析逐日资料和中国160站月降水观测资料，及中国东部季风区夏季四类雨型（北方型、中间型、长江型和华南型）的划分结果，分析了东亚水汽输送与中国东部季风区夏季降水的关系，比较了四类雨型的水汽输送、收支特征及其差异，结果表明：（1）夏季影响中国东部季风区的水汽通道主要有以下6条：印度洋通道，表征印度季风区偏南的西风水汽输送；高原南侧通道，表征印度季风区偏北的西风水汽输送；太平洋通道，表征由西太平洋副热带高压（副高）带来的西太平洋的水汽；西风带通道，表征西风带的水汽输送；孟加拉湾通道，表征来自孟加拉湾向北的水汽输送；南海通道，表征来自印度洋和孟加拉湾在中南半岛转向及来自南海的水汽；与中国东部不同地区降水异常相联系的水汽通道存在明显的差异，且同一条水汽通道在夏季不同阶段与降水的关系也不尽相同。（2）四类雨型的水汽输送和收支特征有明显的差异，华北盛夏降水主要受亚洲季风水汽输送的影响，其次是西风带水汽输送，北方型年二者往往偏强，尤其是季风水汽输送增加一倍以上，贡献也明显增加，20世纪70年代中期之后，季风水汽输送显著减弱，西风带水汽输送的重要性相对增大；淮河流域夏季降水异常主要受太平洋通道水汽输送异常的主导，其次是高原南侧通道水汽输送，二者偏强并在淮河流域辐合时，淮河流域降水偏多形成中间型年；长江中下游地区夏季降水主要受太平洋通道水汽输送异常的主导，长江型年，副高西北侧的西南水汽输送异常加强，并与北方冷空气异常在长江中下游地区辐合，区域为正的水汽净收支；华南地区夏季降水则受印度洋通道、太平洋通道及南海通道的共同影响，当三条通道异常偏强，水汽与北方冷空气在华南地区辐合，形成华南型年。本研究所得结论加深了我们对四类雨型形成机理的认识，并为汛期主雨带的预测提供了参考。
关键词:中国东部季风区/
夏季雨型/
水汽输送
Abstract:Using the reanalysis data from National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) and the classification result of FRP (four summer rainfall patterns)(NCP:the northern China rainfall pattern; IRP:the intermediate rainfall pattern; YRP:the Yangtze River rainfall pattern; SCP:the southern China rainfall pattern) over eastern China monsoon region based on monthly rainfall data collected at 160 weather stations in China, climatological characteristics and differences of moisture transport over eastern China monsoon region and their relationships with summer precipitation of the FRP are investigated.The results are as follows.(1) There exist six MTC (Moisture Transport Channel) that affect the summer rainfall over eastern China.The first one is IOMTC (the Indian Ocean Moisture Transport Channel), which represents the northern moisture transport path from Indian monsoon region.The second one is TPMTC (the Tibetan Plateau Southern Side Moisture Transport Channel), which is the southern moisture transport path from Indian monsoon region.The third one is POMTC (the Pacific Ocean Moisture Transport Channel), which is the moisture transport path from the Western Pacific to eastern China under the influence of WPSH (the Western Pacific Subtropical High).The fourth one is WMTC (the Westerly Moisture Transport Channel), which indicates moisture transport from westerly circulations.The fifth one is BBMTC (the Bay of Bengal Moisture Transport Channel), which indicates the northerly moisture transport from the Bay of Bengal.The last one is SCSMTC (the South China Sea Moisture Transport Channel), which is the path of moisture that comes from the Indian Ocean and the Bay of Bengal and turns to the Indo-China Peninsula and the moisture that is originated from the South China Sea and merges into the crossing equator flow.The moisture transport paths associated with precipitation anomalies over different areas in eastern China are obviously different.Furthermore, the relationship between the same moisture transport path and precipitation in different summer stages is not entirely the same.(2) There are obvious differences in moisture transport and budget corresponding to the FRP.The midsummer (July and August) precipitation anomaly in the North China is most influenced by the Asian monsoon moisture transport, followed by that of the westerly moisture transport.In NCP years, the above two types of moisture transport both tend to be much stronger, especially the former whose strength can be more than doubled and its contribution to NCP also increases significantly.However, the moisture transport by Asian monsoon circulation underwent an abrupt weakening at the end of the 1970s, while the contribution of westerly moisture transport to NCP increased.The anomalous summer precipitation over Huaihe River Basin is significantly correlated primarily with the POMTC and secondarily with the TPMTC.The precipitation over the Huaihe River Basin increases when the moisture transport of the two types of MTC enhance and converge over Huaihe River Basin, leading to the formation of the IRP.The summer precipitation over MLYRB (the middle and lower reaches of Yangtze River Basin) is dominated by anomalous moisture transport of POMTC.As for the YRP years, the moisture transport from the northwestern side of the WPSH strengthens and the warm moist air interacts with cold air from the north over the MLYRB.The summer precipitation over South China is affected by the IOMTC, POMTC and SCSMTC.When the moisture transported from the above three MTCs are stronger and converges with cold air from the north over South China, the SCP forms.The results of this study can enhance our understanding of the formation mechanisms of the FRP, and provide a reference for the prediction of the main rain belt during rainy season.
Key words:East China monsoon region/
Rainfall pattern in summer/
Moisture transport
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