一次梅雨暴雨的动能谱特征分析及收支诊断

利用WRF模式和NCEP再分析资料,对一次梅雨暴雨个例进行了数值模拟,基于高分辨率的模拟结果计算了水平动能谱、涡旋动能谱及辐散动能谱,诊断了动能收支谱方程。结果表明:在暴雨发展阶段,各个高度上都有中尺度动能增长,其显著增加始于中尺度低端,这导致了在中尺度波段出现谱转折特征,但在不同高度转折尺度不同;对流层高层涡旋动能大于辐散动能,平流层低层反之;不同降水阶段、不同高度和不同尺度上动能的来源不同,对流层高层,中尺度动能倾向由非线性项和气压项贡献;平流层低层,气压项的作用更为明显。

Kinetic Energy Spectrum Analysis and Budget Diagnosis of a Mei-yu Rainstorm

Using the WRF model and NCEP reanalysis data, the authors numerically simulated a real Mei-yu rainstorm. Based on the high-resolution simulation results, the authors calculated the HKE (horizontal kinetic energy), VKE (vortex kinetic energy), and DKE (divergence kinetic energy) spectra, and determined the kinetic energy budget. The results show that in the development of the rainstorm, the mesoscale kinetic energy increases with height, with significant increases starting at the lower end of the mesoscale, which leads to the spectral transition characteristics in the mesoscale band. However, the transition scales vary at different heights. In the troposphere, the VKE is greater than the DKE, and in the tropospheric layer the opposite is the case. Different precipitation stages, different heights, and different scales have different sources of kinetic energy. In the upper troposphere, the contributors to mesoscale kinetic energy tend to be nonlinear and pressure terms. In the lower stratosphere, the effect of pressure is more obvious.