%0 Dataset
%T Heihe River comprehensive remote sensing joint experiment: differential GPS positioning survey data of super sample plot of Dayekou guantan forest station (2008)
%J National Cryosphere Desert Data Center
%I National Cryosphere Desert Data Center(www.ncdc.ac.cn)
%U http://www.ncdc.ac.cn/portal/metadata/c7823bb1-189f-4f87-9462-943792301d56
%W NCDC
%R 10.12072/ncdc.NIEER.db1920.2022
%A Liu Qingwang
%A Chen Erxue
%K Sample plot;geographic positioning;differential GPS;geodesy / gravity
%X The super sample plot consists of 16 sub samples. In order to locate each tree in the sample plot and facilitate the positioning of ground-based radar observation base station points, it is necessary to measure the geodetic coordinates of sub sample plot corners and preset ground-based radar base station points. The positioning of these points and each tree is measured by total station. Since the total station measures relative coordinates, in order to obtain geodetic coordinates, at least one reference point needs to be measured with high precision by differential GPS (DGPS) around the super sample plot. In addition, we also observed the geodetic coordinates of all corners of the sub sample with DGPS, and the measurement results can form the verification of the measurement results of the total station. This data set is based on all positioning result data obtained from DGPS measurement, excluding the positioning result of total station. The measurement time is from June 1 to 13, 2008, using the French Thales differential GPS measurement system, model z-max. The observation method is to use two GPS receivers for synchronous static measurement. One is the base station, which is set next to Gansu Water Conservation Forest Research Institute (the WGS geodetic coordinate of the base station is a first-class benchmark introduced from Zhangye City through multi station observation by z-max). The other is a mobile station, which is placed on the observation point of super sample plot. The observation duration of each point varies from 10, 15, 20, 25 and 30 minutes. The specific duration depends on the satellite signal. When the signal is different, it will be measured for several minutes. The final positioning result is obtained by post differential processing with the processing software of the instrument. WGS geodetic coordinate system is adopted for positioning results. Firstly, six temporary control points were measured in the open area next to the super sample plot to