Statistical Characteristics, Formation Causes And Structural Analysis Of MCCs In East Of The Tibetan Plateau In China During Summer From2007to2012

Mesoscale convective complex(MCC) usually correlates with the rainstorm directly, and has an important influence on the precipitation of China. Based on the FY-2D and FY-2E geostationary satellite black body temperature data in summer (June to August) from2007to2012, the mesoscale convective complexes in east of the Tibetan Plateau in China were investigated and then classified into MCC and similar MCC(Eccentricity is in0.5-0.6).The results reveal that there are190MCCs and62similar MCCs in summer during the6years. The MCCs and similar MCCs occurred in southwest and south China account for60%of all and central-eastern China27%. MCCs and similar MCCs in northeast, northwest and north China are the least. The land and sea properties of formation and dissipation regions of two types of MCCs are similar. MCCs in northeast and north China usually move towards northeast and central-eastern China mainly to southeast. Most of the MCCs in south and southwest China with a variety of moving directions do not move. There are most MCCs in June and similar MCCs in July from the monthly variation view. The diurnal variation of MCCs is distinct in different regions. MCCs in southwest China usually form before midnight22:00～23:00, mature in the early morning of03:00～04:00, and dissipates in the morning of06:00～08:00. Most of MCCs in northeast, north, central and eastern China generate in the afternoon of16:00～18:00, reach their mature stage at night of19:00～23:00or early morning of02:00～03:00, and dissipate at night of21:00～01:00. MCCs in south China form around midnight of23:00～03:00, mature around midday of11:00～14:00and wither away of14:00～15:00. Using numerical model simulate the typical cases of MCC and the terrain sensitivity test, and then analyze scale structure.Using mesoscale numerical model WRF, a typical MCC happened in Guizhou on June20119-10is numerically simulated. The MCC is affected by short-wave trough in the middle latitudes, located in divergence area of the northeastern part of South Asia High in the high-level200hPa, and nearby shear line in the low-level850hPa, it is formed and developed by the interaction of high and low air jet. The water vapour is come from the Bay of Bengal and the South. The precipitation is more likely to occur in the area of the maximum gradient TBB.In addition, on the basis of the topographic sensitivity test, MCC generates delayed, weakening of the rain belt and moved south, also the precipitation decreased when the topography be halved. The possible reason for putting off the formation time of MCC cloud and weakening the development of convection is solar radiation. The results show that the topography plays important roles in the affecting intensity and distribution of MCC rain.