包含正定水汽输送算法改进的MM4中尺度模式与暴雨实例数值试验

A MESOSCALE MODEL INCLUDING POSITIVE WATER TRANSPORT ALGORITHMS AND NUMERICAL EXPERIMENT

中文关键词:  中尺度模式  水汽输送  输送格式

英文关键词:Mesoscale model  Moisture transport  Transport scheme

中文摘要:

      暴雨预报是一个既重要又十分困难的问题。水汽条件是产生暴雨的关键,水汽的平流输送在模式的水汽方程中占有重要地位,模式对暴雨的预报能力必然涉及到水汽输送的计算精度问题;本文以著名的中尺度模式MM4为基础,理论测试和分析为依据,以引入新的正定高精度水汽输送算法作为消除模式水汽负值和改进中尺度模式预报能力的途径,研制了取名为改进的MM4中尺度模式,该模式除仍保留原MM4模式的所有功能外,增加了5种水汽输送算法的改进与选择,这5种算法是:1)B网格二阶守恒中心差(原MM4平流格式),2)上游差分,3)Bot(2阶),4)Bot(4阶),5)Prather格式。多个暴雨、台风个例试验表明模式预报能力对水汽输送算法精度有显著的依赖性,采用高精度的水汽输送算法水汽保证正值并提高了模式对暴雨区、降水结构、雨团活动的预报能力。改进水汽输送算法的精度是提高中尺度模式对暴雨预报能力的重要途径。

英文摘要:

      It is a very important and difficult problem for prediction heavy rain. The moisture transport plays important role in modeling the mesoscale weather process. Based on mesoscale model MM4, by cooperating with some more accurate water transport schemes, a mesoscale numerical weather prediction system NMM is developed. These schemes include: (1) B-grid Center Conservative Scheme which is used in MM4; (2) Bott (2-order) Scheme;(3) Bott (4-order) Scheme; (4) Upstream Scheme; (5) Prather Scheme. Bott Scheme and Prather Scheme Both Schemes are positive and produces a lit tle numerical diffusion and computation dispersion. Numerical experimete of move heavy rain process under the model water transport algorithm's options of B-grid Center Scheme, Upstream scheme and Prather Scheme shown the high accurate water transport algorithms, just like Prather scheme improving the precipitation prediction of the mesoscale model and giving more accur ate results of the short range precipitation system.