ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Archive > Volume 41 Issue 8 > 2015,41(8):953-963. DOI:10.7519/j.issn.1000-0526.2015.08.004 Prev Next
Analysis on Mesoscale Convective System During a Shear and Cold Front Type Rainstorm Process in Yunnan Province
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Abstract:
Based on NCEP/NCAR analysis data (1°×1°, 4timesaday) and various dense observation data, a typical shear and cold front type rainstorm process in Yunnan Province was diagnosed and its mesoscale characteristics were analyzed. The results show that the northwest air flow leads cold air and shear line to move south, location of surface cold front is consistent with shear line, warm air and cold air converge near shear line and cold front, leading to heavy rainfalls. Efficient and reasonable configuration of synoptic scale systems and their interaction provide the background for mesoscale convective systems. The distributions of high CAPE area and dense isoline area of Δθse (500-800) correspond to the convective systems. Mesoscale characteristics of the local and sudden rainstorm are closely related to surface mesosacle convergence systems. The location and movement of surface cold front and the overlaid intensive wind field convergence area could be used as important reference for the imminent forecast of shorttime severe precipitation. The intensity and location of rainfall are related to gradient of TBB isolines and the location of the largevalue zone of the gradient. The occurrence and development of CloudtoGround lightning could be one of criteria indicating occurrence and development of convective cloud cluster. There is a complex relationship between the time of lightning frequency peak value and the time of rainstorm peak value at different rainstorm sites in lowlatitude plateau because of various factors. The existence of the gale area, the second type mesoγ scale convergence area and “train effect” are the direct causes for local heavy rainfall. Boundary layer jet plays an important role in dynamic trigger and vapor transport in this process.
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