سال انتشار: ۱۳۸۱

محل انتشار: همایش ژئوماتیک ۸۱

تعداد صفحات: ۱۰

نویسنده(ها):

A. A. Ardalan – Department of Surveying and Geomatics Engineering, University of Tehran, P.O. Box 11365-4563, Tehran Iran,
E. W. Grafarend – Department of Geodesy and Geoinformatics, Stuttgart University, Geschwister-Scholl-Str. 24 D, D-70174,Stuttgart Germany,

چکیده:

Four fundamental geodetic parameters, namely 0 2 { , GM W,Ω,J}, determine a world geodetic datum. With respect to the Somigliana-Pizzetti Level Ellipsoid / International Reference Ellipsoid these fundamental parameters from best estimates at a reference epoch determine its semi-major axis a as well as its semi-minor axis b (or equivalently the linear eccentricity ε = a2−b2). Satellite orbit analysis as well as sea level projects have indicated that the four fundamental geodetic parameters are time-dependent, described for instance by 0 {(GM)!,W! 2 , , } J Ω! ! . Here we have 0 {(GM)!,W! ,Ω! ۲ ,J! }. Here we have analyzed the impact of best estimates of 0 2 {W! ,J!} on shape and size parameters, i.e., {a!,b!} and {a!,ε!}, of the World Geodetic Datum 2000 (WGD2000). Based on the best estimate of time variations of 0 2 {W! ,J!} we have computed the best estimates a! = (0.3 ± ۰٫۰۲) mm/year , b! = (−۰٫۰۰۰۲ ± ۰٫۰۰۰۰۸) mm/year , and ε! = (۳٫۷ ± ۰٫۳) mm/year as the time variation of the shape and size parameters of the WGD 2000. The new results give a scientific basis for answering the question: Is there a need for a Geodetic Datum 2000?