EFFECTS OF DIABATIC PHYSICAL PROCESSES ON THE SIMULATION OF MESO-β SCALE STRUCTURE OF A SQUALL LINE SYSTEM

The effects of different convective parameterization,explicit moisture schemes and surface heat-ing on the meso-β scale structure of a squall line system are investigated,by using an improvedmesoscale model.It is found that the successful prediction of mesoscale convective systems hinges up-on not only the sub-grid scale convection,but also the resolvable scale phase change processes and thediurnal variation in the boundary layer.The simultaneous operation of the Fritsch-Chappell convectivescheme with parameterized moist downdrafts and the prognostic equations for cloud water (ice) andrainwater (snow) seems to be essential in simulating realistically MCSs and reducing or eliminatingthe unrealistic development of the CISK-like instability associated with the squall line system.