Statistical Analysis of Summer MCS in Middle Eastern China

The detailed research work on classification of mesoscale convective system (MCS) is still less at present. The spatial and temporal characteristics of summer MCS in middle eastern China (110-124°E, 27-40°N) are investigated by FY-2 geostationary satellite infrared digital cloud images during 2008-2010. According to the size, the classification scheme used for this study includes two previously defined categories: meso-a mesoscale convective system (MaCS) and meso-b mesoscale convective system (MbCS). Then based on the shape, MaCSs are classified mesoscale convective complexes (MCC) and persistent elongated convective systems (PECS), MbCSs are classified meso-b circular convective systems (MbCCS) and meso-b elongated convective systems (MbECS). The results show that there are 208 MCSs in summer during the three years, including 68 MaCSs and 140 MbCSs. The elongated systems are the most common type of MCS in summer in this region and these systems accounted for 79.3% of the total. From inter-monthly variation point of view, there are most MCSs in July, the second in August, least in June. The moving routes also have been studied in this paper, most MCSs moved from the west to the east and some from the south to the north or the north to the south. The path from the east to the west is rarely. The peak period of MCS initiation is during 09:00 to 10:00 UTC, and the mature period is about 10:00 to 11:00 UTC. Most of the systems dissipated between 12:00 and 13:00 UTC. The life scale of MCS is about 6.5 hours. MaCSs from the initiation to mature stage need about three to four hours, while from mature to termination phase should last for about four to five hours. For MbCSs, the development and weakening stage have the same time about two to three hours.

Keywords: MCS; geographical distribution; shift path; inter-monthly variation; diurnal variation