Preliminary Research on Flooding Torrential Rain Caused by Interaction of MCC and Meso-â Scale Convective Cell in China

Using various synoptic data as satellite image, NCEP data, surface observation data and upper level wind data, the two flash flood events caused by interaction of MCC and meso-b scale convective cell were studied. Results show thatF(1) the torrential rain area caused by interaction of MCC and meso-b scale convective cell is small and its precipitation intensity is big ,so its disaster is specially big; (2) the background circulication favorable to eastward motion of MCC and meso-b scale convective cell developing are composed of strong divergence development on 200 hPa level, generation and stability of lower-level jet stream on 850hPa, eastward motion of honrizontal shear at the front of lower-level jet stream with convergence development on 500 hPa; (3) the lower-level jet stream provided water vapor and energy transportation for MCC and meso-b scale convective cell developing ; (4) wind shear on the ground surface and motion of the low-value tongue of surface energy ratio contributed to one of triggering mechanisms of MCC and meso-b-scale convective cell development. The high-value region generation, motion of low-value tongue and shear line on surface, and generation of large gradient region of surface energy ratio showed indication to generation and evolution of MCC and meso-b-scale convective cell; (5) generation and change of high-value region of CAPE with low-energy tongue on lower level of tropospere, frontogenesis, and Z-spiral change also show indication to generation and evolution of MCC and meso-b-scale convective cell; (6) the strong divergence developing on upper level and the strong upward motion generating in region containing MCC are the dynamic mechanism for development and mantainance of MCC and meso-b-scale convective cell; (7)the two torrenrial rain events are characterized in complete different 3-dimensional vorticity structure which deserves special attention in torrrential rain forecast servive of this kind; (8) On the basis of further research for two torrential rain events, the conceptual model of the flooding torrential rain caused by interaction of MCC and meso-b scale convective cell is offered . Key words: MCC meso-b scale convective cell torrential rain interaction