GEOSAT卫星的ERM测高数据处理与中国近海海平面

对ＧＥＯＳＡＴ测高卫星在中国近海区域（０°－３５°Ｎ,１０５°－１２７°Ｅ）以及１２７°－１３５°Ｅ内６个ＥＲＭ周期（１９８７年１月１日－４月１２日）的地球物理数据记录（ＧＤＲ）中的数据进行了编辑和预处理．根据卫星弧段的实际长度选取了混合轨道误差模型,并采用最小二乘技术对上升弧段与下降弧段交叠点处的不符值进行了平差计算．处理结果表明,所选用的方法可以大大地消除径向轨道误差的影响,使交叠点处的不符值由原来的５６ｃｍ（ＲＭＳ）降低到现在的２４ｃｍ（ＲＭＳ）在此基础上,构造出６个１°×１°的中国近海海平面及其平均海平面．该平面被称为＂测高大地水准面＂与美国Ｏｈｉｏ州立大学的ＯＳＵ９１Ａ重力场模型的大地水准面相比,两者具有同等量级的精度及一致的形态。

GEOSAT/ERM SATELLITE ALTIMETER DATA PROCESSING AND THE MEAN SEA SURFACE IN THE REGION OF CHINA SEA

The six 17-days （Jan.1 to Apr.12,1987） GEOSAT/ERM altimeter data in the region of China sea（0°-35°N,105°-135°E）have been edited and preprocessed in this paper to reduce the bias effects such as instrument bias, tide bias, atmosphere bias, sea state bias, attitude bias and etc. The mixed radial orbital error mode1 has been adopted which is either a single parameter model or a double parameter model according to the arc length of GEOSAT/ERM satellite. Then least square adjustment has been used to the discrepancies of the crossover points of the ascending arcs and the descending arcs. The results show that the mixed orbital model and crossover adjustment can reduce the effect of the radial orbital error significantly. The discrepancy of crossover point is reduced from 56cm（RMS） to 24cm （RMS）. On the basis of these, six 1°×1°sea surface and its mean sea surface in the region of China sea are computed. If the time variations and invariations of sea surface topography are ignored, this mean sea surface can be regarded as the so-called "geoid" under normal conditions, or the "altimetric geoid" in more accuracy. Compared with the geoid of OSU91A gravity model, it can be seen that both of them are much consistence.