The Effects of Ambient Wind on Simulating Convective Clouds

The two—and three—dimensional versions of a fully elastic numerical cloud model with ice phase microphysics parameterization are used to investigate the evolution and surface precipitation features of convective clouds in unidirectional low—level wind shear fields. The simulations show that, in order to trigger a convection in low level wind shear environment by thermal bubble, a more intensive temperature disturbance is needed, whereas it can be initiated much easier by cold outflow. Low—level shears with certain intensity lead the peak intensity of convections to decrease, but result in a longer lifetime, larger amount of cumulative surface precipitation, and more extended rainfall area with some smaller peak rainfall rate. Although the two—dimensional simulations of convective activities in vertical shear environment have some severe distortions, the evolution features of maximum updraft velocities and total surface precipitation are coincident with the results of the three—dimensional simulations.