WRF模式对青藏高原南坡夏季降水的模拟分析

The simulation analysis of the precipitation over the southern slopes of the Tibetan Plateau based on WRF model

利用中尺度数值模式WRF研究积云对流参数化方案、网格嵌套技术和模式分辨率对陡峭的青藏高原南坡夏季降水模拟的影响。对2006年7月青藏高原南坡地区降水的模拟分析表明:降水对积云对流参数化方案的选择很敏感,不同方案模拟的结果差异显著,采用Grell-Devenyi质量通量方案时的模拟效果优于其他方案。在此基础上,通过5种试验方案比较发现,使用积云对流参数化方案、提高模式分辨率和应用网格嵌套技术能改善降水强度和空间分布的模拟,组合使用时模拟的降水与观测资料更接近。它们均能改进风场,使得水汽的输送和辐合过程的模拟更加准确;还能影响大气的垂直加热状态,导致不同的对流发生,使垂直速度的分布趋于合理。未使用积云对流参数化方案时,大气湿度偏小,而模式分辨率和网格嵌套技术对大气湿度的影响不大。

Impacts of cumulus parameterization schemes, grid nesting approach and model resolution on the simulation of pre- cipitation in July 2006 over the southern slope of the Tibetan Plateau have been studied by using WRF model. The result shows that the simulated precipitation is very sensitive to cumulus parameterization scheme. Different schemes have different results, and the result simulated by using Grell-Devenyi mass flux scheme is better than results using other schemes. The comparison of results of five sensitivity experiments indicates that, the use of cumulus parameterization scheme, the increased resolution, and the tnesting approach can improve the simulated intensity and spatial distribution of precipitation. The simulation is better when these three approaches are used jointly. These approaches can improve the wind field simulation, which is beneficial for the simulation of water vapor transport and its convergence, and vertical heating and convection, and the distribution of vertical ve- locity. The simulated atmospheric humidity decreases without using a cumulus parameterization scheme, while model resolution and the nesting approach have little impacts on the humidity simulation.