On the Role of Convective Momentum Exchange in the Mesoscaie Gravity Wave

[摘要] The mesoscale disturbances are characterized by the gravity wave which accompanies the field of convergence of the order of 10-4sec-1. This amount of convergence strongly controls the convective activity and has a significant influence upon the wind field through the momentum exchange process.Numerical experiments are made by means of the simplified two layer version of sheared flow incorporated with convective momentum transfer which is parameterized empirically. It is shown that the downward momentum transfer in the lower-level coinvergence area has an effect of increasing the lower-level wind velocity and decreasing the upper-level wind velocity and thus results in the self-intensification of lower-level convergence and increasing the velocity of propagation downstream. The redistribution in the wind profile, however, contributes to the strengthening of frictional dissipation, which is partly compensated by the energy conversion from convective kinetic energy.

[学科分类] 大气科学