大气对地球自转变化的影响-方法和数据的深入分析

Earth's Rotation Variation Excitated by Atmosphere - Further Analysis for Method and Data

大气相对固体地球的运动产生大气相对角动量,它的变化可以激发地球自转多 时间尺度的变化．计算大气相对角动量现在采用两种不同的垂直积分高度,一种为从地形 表面积分到顶层大气,称之为SP方法;另一种为从1000 hPa积分到顶层大气,称之为 BP方法,对采用这两种方法所得到的大气相对角动量进行了详细的比较．应用欧洲中距 气象预报中心(ECMWF)和美国国家环境预报中心(NCEP)大气再分析数据,重新研究 了大气相对角动量变化的时空特征．通过对大气相对角动量季节平均,季节振幅和时空特 征的分析,得出ECMWF和NCEP的大气相对角动量变化对地球自转周年极移的影响, 在亚洲季风区域和南极洲区域差别最为明显．

The atmospheric motion with respect to the solid Earth causes relative atmospheric angular momentum （RAAM）, which variation excite the Earth＇s rotation change at the multi-temporal scales. There are two methods to be applied to compute RAAM. One is the SP method, by which wind contribution on RAAM is integrated from Earth＇s surface to top pressure level. Another is the BP method, by which the integration is from 1000 hPa to top pressure level. We compare the RAAM difference caused by the two methods in detail, and calculate the RAAM temporal variation and spatial characteristics based on the meteorological reanalysis data coming from the European Center for Medium range Weather Forecast （ECMWF）, and the National Centers for Environmental Prediction （NCEP）. The results show that the obvious differences between the ECMWF and NCEP RAAM excitations on annual polar wobble are mainly located in the Asian monsoon area and the Antarctic region.