有限区域流函数和速度势的3种求解方法在分析台风Bilis暴雨增幅中的比较研究  

Comparison Study of the Impacts of Three Approaches for Calculating Streamfunction and Potential Velocity in a Limited Domain on the Analysis of the Rainfall Enhancement of Typhoon Bilis

作　　者：任晨平[1,2] 曹洁[3] 王黎娟[1] 崔晓鹏[3] 

机构地区：[1]南京信息工程大学大气科学学院 [2]中国人民解放军94754部队气象台 [3]中国科学院大气物理研究所云降水物理与强风暴重点实验室

出　　处：《气候与环境研究》2013年第6期721-732,共12页Climatic and Environmental Research

基　　金：国家重点基础研究发展计划项目2009CB421505;国家自然科学基金项目41175056;国家自然科学基金海峡两岸合作研究项目40921160379

摘　　要：将有限区域流函数、速度势求解中常用的两种张驰法(即理查逊法和加速利布曼法)与调和—余弦谱展开法(H-C法)进行了比较,理论研究表明:H-C法单独考虑边界影响分量,物理意义明确,且不会丢失边界上的天气系统;从计算上看,H-C法重建的风场能精确还原原始风场,且计算效率明显高于两种张驰法,即收敛更快。通过在台风Bilis(0604)暴雨增幅过程诊断中的应用发现,常用的两种张驰迭代方法在求解有限区域流函数和速度势的问题上效果都不是很好,即:用理查逊法和加速利布曼法计算的流函数和速度势重建的风场与原始风场差别较大,不能准确还原原始风场;用H-C法不仅计算效率高,还原的风场与原始风场差异极小,且不受南边界较强的西南季风涌影响,在暴雨增幅前期能较好地反映与暴雨增幅相关的强辐合信号。因此,可用H-C法计算得到的无辐散风和无旋风对有限区域的天气系统进行更深入的动力结构分析。The relaxation methods （Richardson method and accelerated Liebmann method） and the harmonic-cosine series expansion （H-C） approach to compute the stream function and velocity potential in a limited domain were compared. Theoretical derivations show that the H-C approach takes consideration of the boundary conditions by computing a separate component. It not only has solid physical meanings, but also avoids missing weather systems near boundaries. In addition, this approach can reconstruct the wind field accurately and has much higher computationalefficiency than the other two methods. The diagnostic analysis of the rainfall enhancement of typhoon Bilis shows that the following： 1） the horizontal wind cannot be recovered fully by the two relaxation methods, while the H-C approach gives much more accurate and efficient results and preserves the influences of monsoon surge at the southern boundary; 2） the H-C approach presents strong convergent signals previous to the abrupt rainfall enhancement. Therefore, the partitioned non-divergent and irrotational wind obtained from the H-C approach can be used in deeper dynamic studies of weather systems in the future.

关 键 词：有限区域 调和一余弦谱展开法 台风Bilis 暴雨增幅 

分 类 号：P458.124[天文地球—大气科学及气象学]