A study of the meteorological background of convective systems over the Tibetan Plateau

Convective systems originated from Tibetan Plateau are classified and their horizontal and vertical dynamic and thermodynamic structures are examined using the ISCCP data of tracks of convective systems, the NCEP/NCAR reanalysis data and the TRMM 3B42 from 1998 to 2004 during northern hemisphere summer (June-August). The results reveal that convective systems mainly form over the southeastern Tibetan Plateau. Convective systems are classified into three categories:Staying over the Plateau and southward and eastward moving out of the Plateau. The movement and development of convective systems are determined by surrounding environmental meteorological conditions. The convective systems with strong upward motion and plenty of water vapor may move out of the Plateau, whereas those with weak upward motion and small amount of water vapor stay and dissipate over the Plateau. The southward and eastward movements of convective systems are steered by surrounding northerly and westerly winds.