ISSN 1006-9895

CN 11-1768/O4

Characteristics and Differences of Summertime Moisture Transport Associated with Four Rainfall Patterns over Eastern China Monsoon Region
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    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.

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History
  • Received:November 26,2016
  • Revised:
  • Adopted:
  • Online: January 27,2018
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