| 1 | A Synoptic Overview and Moisture Tra jectory Analysis of the“7.21” Heavy Rainfall Event in Beijing显示文摘The heavy rainfall in Beijing on 21 July 2012 was a high impact event. First, a synoptic overview of this event is presented based on the ECMWF reanalysis and forecast data, together with observations of hourly precipitation. It is found that an east to northeastward moving 'low-level northwest vortex' caused this event. The vortex was formed under favorable circulation patterns and intensified by low-level dry intrusions. The source regions of the large volume of moisture necessary to sustain the intense rainfall are diagnosed by back-trajectory analysis. Approximately 77% of the moisture was transported from the Bay of Bengal(Bo B). The transport processes, including vertical profiles, mean humidity variations, and relative importance of the rain-paths, are further quantified by the back-trajectory analysis and cluster analysis.The results highlight the importance of the southwestern path in transporting moisture to northern China,which accounts for 88.4% of the moisture from the Bo B, and 68% of the total of the '7.21' heavy rainfall event. | 李林涛 Albertus J.Dolman | 2016 | Journal of Meteorological Research2016，30，1： | 3 |
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