中国南极长城站测绘基准系统的建立

ESTABLISHMENT OF THE SURVEYING SYSTEM IN THE CHINESE CREAT WALL STATION AREA, ANTARCTICA

经1985年12月～1987年3月,三年度夏测绘科学考察,在中国南极长城站地区建立了一套完整的、精确的测绘基准系统。它包括大地坐标系统、高程系统和重力参考系统。本文叙述了建立这些基准系统的方法和数学模型,并分析了测量精度。

In the Great Wall Station area, Antarctica, a complete and accurate surveying system has been established during three years of the Antarctic surveying research expedition. In this paper, the author discusses the surveying methods for establishment of the system, the model for data processing and accuracy of analysis of the reaults. 1. Establishment of the Great Wall Station geodetic coordinate System.The datum point was set up on the West Mountain to west of the Grest Wall Station. The datum parameters were determined by satellite Doppler positioning method.The WGS-72 reference ellipsoid was adopted and the coodinate is B = 62°12'59' 782(S), L = 58°57'52' 546(W). Then Gauss horizontal Cartesian coordinate system was established by using Gauss direct projection formula. In the Great Wall Station area, a horizontal trilateration control network was also set up taking the datum point as origin. The coordinates of network points were com- puted using rank defect free network adjustment. 2.Establishment of the Great Wall Station elevation system.The geoid of Great Wall Station was determined by using combined artificial tide gage and automatic tide gage data. From the connected measurments, an elevation of levelling origin is determined to be 6.741m. The Great Wall Station normal height system was then established after setting up the first order levelling network. In the Great Wall Station area, the elevation control points are coincident from horizontal control points and were observed with eletromagnetic distance triangulated height method.The height differences were calculated with accurate formula. In the observation, the deflection of the vertical correction and the refraction effect correction were added in. After step-by-step approach adjustment, the elvations of control points were obtained by weighted mean of adjustment values. The accuracy of elevation is similar to IV-order levelling. 3.Establishment of the Great Wall Station gravity reference system. A gravity basic point was set up in front of the office building. From the connected measurments with South American Intenational Gravity Standard Network point, a gravity value is determined to be 892208.68± 0.04 mgal. The gravity network points in the Great Wall Station area are coincident with horizontal control points and were measured with Lacoste-G gravimeter. Gravity values of the points were obtained by adjustment.The geoid undulation and the vertical deflection were also computed with Stokes and Vening-Menesz integration. The geoid map and free-air gravity anomaly map of the Great Wall Station area were also drawn.