闭合气压系统中心位置指数的计算方案

王盘兴等在＂闭合气压系统环流指数的定义及计算＂一文中定义了闭合气压系统的面积指数S、强度指数P和中心位置指数（λc,φc）,并给出了它们的计算方案。但其中（λc,φc）的计算方案对低纬系统的计算存在明显误差,误差原因是原方案中的极点球面坐标系不适合低纬系统的计算。本文建立了一套原点位于搜索区Ω中心的新球面坐标系,通过坐标转换实现了低纬闭合气压系统中心位置指数（λc,φc）的准确计算。对7月南亚高压和1月蒙古高压中心位置指数（λc,φc）的实际计算表明,它既消除了低纬系统（南亚高压）（λc,φc）原计算方案的明显误差,又保持了与高纬系统（蒙古高压）（λc,φc）原计算方案计算结果的一致。因此,本文给出了适于计算任意纬度闭合气压系统中心位置指数（λc,φc）的计算方案。

Calculation Method of Center Position Index for Closed Pressure Systems

Area index S,strength index P and center longitude/latitude position index（λc,φc） have been defined in the paper Definition and calculation of three circulation indices for closed pressure systems written by Panxing Wang,et al.But the calculated index（λc,φc） for the lower latitude systems exist obvious errors,which is induced by the unsuitable polar spherical coordinate.Thus,a new spherical coordinate with the original point locating in the center of searching area is established,in such a way that the（λc,φc） is accurately calculated.The practical calculations of（λc,φc） for South Asian High in July and Mongolian High in January show that the evident errors are eliminated and the calculated results are in accordance with the original one.Therefore,this method can be applied to random closed pressure systems.