摘要
采用移去恢复技术 ,利用我国高分辨率DTM和重力资料推算我国大陆重力大地水准面 ;然后再和我国GPS水准所构成的高程异常控制网拟合 ,推算了具有dm级精度、15′× 15′分辨率的我国大陆大地水准面。利用全国地壳运动监测网络的 80余个高精度GPS水准点进行外部检核 ,检核结果证实和原设计精度完全一致 ,即该大陆大地水准面的绝对精度 ,在东经 10 2°以东高于± 0 .3m ,在东经 10 2°以西、北纬 36°以北为± 0 .4m ,36°以南为± (0 .4～ 0 .6 )m。利用卫星测高数据计算垂线偏差 ,反解我国海域大地水准面。为了检核 ,由测高垂线偏差反演为重力异常 ,与海上万余点船测重力值进行了外部检核 ;同时用上述反演的重力异常推算大地水准面 ,与直接解得的相应结果进行比较作为内部检核。由重力和GPS水准数据推算的上述大陆大地水准面 ,和主要由卫星测高数据确定的海洋大地水准面 ,二者之间一般都存在以系统误差为主的拼接差。顾及这一现象并结合我国在陆海大地水准面拼接区重力资料稀疏的实际 ,研究提出了扩展拼接技术 ,即在沿海选取部分陆海毗邻的局部地区 ,在这局部地区内 ,陆地用实测平均重力格网数据 ,海洋用测高平均重力格网数据 ,统一推算这陆海局部重力大地水准面。
By using high resolution DTM,global gravity model and surface gravity data Chinese gravity geoid is determined at first,which then is merged into Chinese GPS leveling network to obtain a Chinese mainland geoid.The Chinese ocean geoid is calculated by using the deflection of the verticals,which are derived with the satellite altimeter (Sa) data.Finally the new Chinese geoid is obtained by the combination of mainland and ocean geoids with extending merge tech_nique.There are three steps for the combination.Firstly a local coastal district including coastal area and sallow sea is selected.A local gravity geoid of the district is computed with all the mean girded gravity values in the district.Secondly the land part of the local gravity geoid is fitted to Chinese mainland geoid with some fit_parameters,and the latter keeps in variation during the fitting.Thirdly the Chinese ocean geoid is merged into Chinese mainland geoid with the above fit_parameters.So a new Chinese quasi geoid (CQG2000) covering whole China land and sea territory is obtained with 15′×15′ resolution and dm accuracy.CQG2000 has been examined by 80 GPS leveling points of the Chinese crustal movement monitoring network.The examining results demonstrate that the accuracy of the new quasi geoid is reliable,i.e.the absolute accuracy of the CQG2000 is higher than ±0.3 m in the east of longitude E102°,±0.4 m in the west of E102° and north of latitude N36°,±(0.4～0.6) m in the west of E102° and south of latitude N36°.
出处
《武汉大学学报（信息科学版）》
EI
CSCD
北大核心
2001年第4期283-289,302,共8页
Geomatics and Information Science of Wuhan University
基金
国家测绘局测绘科技发展基金资助项目(C95 0 40 1)
