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Nocturnal Development of Mesoscale cloud clusters in Eastern China during Meiyu Period ($BM{(B $BC]6G(B) $BH/I=MW;](B :

  
 Mesoscale cloud cluster is the important complex convective systems that  
 owns large area rang and long lasting time, it can produce heavy rainfall  
 and have great effect on energy and water cycle. 
  
 It was found that the evolution of mesoscale cloud cluster shows regularity  
 in its convection peak time in one day time (which named diurnal variation  
 of mesoscale cloud cluster here). In North America Continent, the convection  
 of cloud clusters was found by some researchers to tend to peak at night  
 time, we also found a significant diurnal variation in the evolution of cloud 
 clusters in Eastern China continent during Meiyu Period, most of them  
 developed largely around 2 LST in night time with a secondary convection  
 peak in evening time in a few cases. 
  
 To study the diurnal variation of mesoscale cloud cluster and the main  
 factors and dynamical process that reslt in its prominent midnight convection 
 peak can contribute to the knowledge on the mechanism of the largely  
 develpment of cloud cluster and the prediction on its evolution. 
  
 In Eastern China, a quasi-stationary east-west-oriented Meiyu front exist  
 during Meiyu Period, most of the cloud cluster we analyzed occurred along  
 the Meiyu front , the benifit environment for the midnight convection peak  
 of cloud clusters was mainly analyzed in this study. The nocturnal enhanced  
 low level northward wind over large domain south to Meiyu Front, and the  
 resultant water vapor flux convergence over Meiyu front zone was proposed  
 to dominantly contribute to the midnight convetion peak of mesoscale cloud  
 clusters.   
  
  

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mail-to:momoko@ees.hokudai.ac.jp / Tel: 011-706-2359