闭合气压系统中心分布特征量及应用

用单位半径球面上闭合气压系统环流指数P（强度）、C（中心位置）的多年序列,构造了历年系统中心在C-周围分布的3个特征量：1）平均距离r,它定义为历年系统中心C偏离于气候中心C-（即中心位置异常C′）的权重几何平均距离,是系统中心分布区域大小的度量;2）压缩系数μ,它描述了历年系统中心分布区域偏离于圆形的程度,是历年系统中心位置分布各向异性的度量;3）极大异常方向β,它用系统中心极大异常偏离-C处正东方向的角度,给出了系统中心的主要异常方向。对1948—2007年6、7、8月100hPa南亚高压中心位置分布特征量的计算结果表明,它们能简要、精确地描述系统中心位置异常在球面上的分布特征。根据r、μ、β的定义,它们也适用于精确描述球面上其他要素场中闭合系统中心在球面上的分布特征。

Characteristic Quantities of Closed Pressure System Centers Distribution and Its Application

By using the multi-year series of the circulation indices P（intensity） and C（ center location） for the closed pressure system on the unit radius spherical surface, three characteristic quantities of annual system centers（ around the climatological center C） are defined. 1 ） Average distance r, which is defined as the weighted geometric average distance of the annual system centers C deviating from the climatological center C（ i. e. the center location anomaly C＇ ）, is a measurement for distribution area of the system centers. 2 ） Compression coefficient μ, which describes the extent of the annual system center distribution area deviating from circularity, is a measurement for distribution anisotropy of the annual system center locations. 3 ） Maximum anomaly direction β, which indicates the main anomaly direction of system centers by using the angle that the system center maximum anomaly deviates from the east direction at C. The above three quantities of 100 hPa South Asian High（SAH） are calculated in June,July and August from 1948 to 2007, indicating that they can briefly and exactly describe the distribution characteristics of the center location anomalies on the spherical surface. According to the definitions of r,μ and β, they are also suitable for describing accurately the distribution characteristics of closed systems centers in the other meteorological element fields on the spherical surface.