DYNAMICAL INFLUENCE OF MICROPHYSICS IN TROPICAL SQUALL LINES - A NUMERICAL STUDY

Based on environmental conditions of the 22 and 23 June squall lines d uring the Convection Profonde Tropicale in 1981 (COPT81) experiment in West Africa, a series of numerical simulations are performed with a t wo-dimensional nonhydrostatic cloud model to examine the dynamical eff ect of microphysics in tropical squall lines. The role of ice-phase mi crophysics strongly depends on ambient conditions. For the environment of strong convective instability, the ice phase is important regardin g the system-scale structure bur is not important to the convective-sc ale dynamics. On the other hand, the ice influence is crucial to the s quall-line convective system if the environment has a weak convective instability and is almost saturated at low levels.