TWP-ICE试验期间一次热带深对流过程的拉格朗日输送特征

Characteristics of Lagrangian transportation in a tropical deep convective process during TWP-ICE

本文使用高分辨率WRFV3.4.1模式对TWP-ICE试验期间的一次热带深对流过程进行了数值模拟,利用第四重嵌套每五分钟输出一次的模拟资料对对流系统的上升气流质量通量廓线特征进行了分析,并结合FLEXPART拉格朗日粒子扩散模式对热带深对流系统进行拉格朗日轨迹分析.质量通量廓线特征及拉格朗日轨迹的分析结果表明,在条件不稳定层顶附近便有部分水凝物被输送出深对流系统.深对流系统中的水凝物主要沿环境引导气流向深对流下游方向输送.由于受低层风场扰动的影响,少量的水凝物被输送到深对流系统的上游.深对流系统中的水凝物向其下游方向输送的最远距离为200-300 km,并约有10%-20%的水凝物对对流系统下游50-150 km附近卷云砧的形成产生影响,其影响的时间尺度约为4-6 h.

High resolution mesoscale model WRFV3.4.1 is used to simulate the deep convective process during TWP-ICE. Simulation data from the forth nested domain outputted every five minutes is employed to analyze the characteristics of an updraft mass flux profile and the trajectories of convective transportation with the FLEXPART Lagrangian dispersion model. Analyses of Lagrangian characteristics of hydrometeor transportation and mass flux vertical variation show that around the top of conditional instability, some hydrometeor has beendetrained from the deep convective system. Convective hydrometeor is conveyed by steering current from the deep convective system to their downstream. However, influenced by low level wind disturbance, some hydrometeor is also conveyed to upstream. The largest distance over which the hydrometeor is transported from the deep convective system to the downstream is about 200-300 km. About 10-20% of the hydrometeor has an important influence on the anvil area 50-150 km downward from the deep convective system, of which the time scale is 4-6 hours.