微下击暴流的数值模拟

建立了一个具有极高分辨率的二维面对称微下击暴流数值模式，对干、湿两类微下击暴流线在云下的生成和演变过程进行了模拟试验，取得较理想结果。模拟湿微下击暴流线的各种主要结构和演变特征与实测结果吻合较好。干型微下击暴流由冰晶降水元在干绝热气层中下落时的蒸发致冷驱动，只产生了很小的地面降水和降温。 几百米厚的弱稳定层对干微下击暴流有明显阻挡和削弱作用。

Numerical Simulations of the Microburst

A two-dimensional, slab-symmetric microburst numerical model with very fine special resolutionis developed and used to simulate the formation and evolution of the dry and wet microburst lines.Some satisfactory results are obtained. The structure and evolution features of the simulated wetmicroburst lines are coincident with the observations quite well. The dry microbursts, driven by theevaporative cooling of the ice crystal precipitating element falling in a dry adiabatic layer, only producea little ground rainfall and temperature drops. A weak stable layer several hundred meters thick cansignificantly block and weaken the dry type microbursts.