Estimation of Baseline Vectors between First Order Control Points and Simosato based on Analyses of AJISAI SLR Data

Abstract

The Hydrographic Department of Japan (JHD) has operated a mobile SLR station since 1988 in the framework of the marine geodetic control project. In 1996, it has completed a first observation cycle at 14 fiducial points called the First Order Control Points (FOCP) distributed at major off -lying islands and at some coastal areas in Japan. The AJISAI data at all the FOCP were analyzed with global data. The used software is GEODYN-II developed by NASA. The reference fixed stations are GSFC (Maryland, USA) and Haleakala (Hawaii, USA), for which the coordinates of the ITRF93 with its velocity field are adopted as a priori values. The RMS of the resulted range residuals for the FOCP data are 5-10 cm, which is comparable to those of all the global stations. The stability of the solutions for the baseline vectors between the FOCP and Simosato, the stationary SLR station in central Japan, was examined by comparing the solution with those obtained under different estimation conditions. As a result, followings are concluded : (1) the estimated baseline vector can be determined within lcm as far as the coordinates of both the FOCP and Simosato remain as estimated parameters ; (2) it can be well determined by a single arc analysis ; (3) it can be determined within lcm when the frequencies of estimations of the empirical acceleration and the drag coefficient are less than 3days ; (4) the estimation does not depend on the frequency of estimation of the solar radiation pressure coefficient ; (5) the estimation does not depend on the selection of the atmospheric density model if the drag coefficient is appropriately estimated. Comparison of the estimated baseline lengths with those of the marine geodetic results of JHD shows that they agree within 3-4 cm except for three sites.