有限区域风场的分解和重建

Partitioning and reconstruction problem of the wind in a limited region

对有限区域进行旋转风和辐散风的分解,是中尺度系统结构分析的一种诊断方法,可提高对中尺度系统动力结构的认识.一方面,有限区域风场的分解可以给出总风场中无辐散风与无旋转风的不同分布,还可根据这两种风场的分布特征进行不同要求的分析;另一方面,由于耦合边界条件不能直接计算,计算过程中必须简化处理,使有限区域风场分解本身还有许多问题没有很好解决.目前,对风场进行有效分解的方法是对有限区域里的流函数和速度势进行求解,然后对流函数和速度势求导得到对应的无辐散风与无旋转风.有限区域流函数和速度势求解的准确程度主要以分解后的风场能否还原到原始风场(即风场重建)为标准.本文总结了有限区域风场分解和重建的方法,重点介绍了调和正弦/余弦方法,该方法可较准确有效地解决有限区域风场的分解和重建问题,对进一步研究天气系统的动力结构有较好效果.

Partitioning and reconstruction problem of the wind in a limited region is a useful diagnostic technology.From the non-divergent and non-rotational wind component,one can know more about the structures of meso-scale systems.The effective way to wind partitioning and reconstruction in a limited region is to calculate the stream function and velocity potential in the same limited region.When the reconstructed wind approachs the original one,it means the partitioning process is successful and the calculated stream function and velocity potential is accurate.The most commonly used partitioning methods in the past are summarized in this paper,and the harmonic-sine/cosine method is emphasized.Case study shows that the harmonic-sine/cosine method can partition and reconstruct the wind in a limited region,and its results are encouraging for studying the dynamical structures of meso-scale systems.