SITE SELECTION AND EVALUATION OF CHINA'S NEW RADIOMETRIC CALIBRATION TEST SITES

Abstract. The ideal radiometric calibration site is the basis for achieving on-orbit radiometric calibration. At present, China mainly uses the Dunhuang national test site for on-orbit radiometric calibration. However, the Dunhuang national test site has a shortage of ground objects and surface damage, and it is urgent to select and evaluate the new calibration sites. By analyzing the calibration site selection requirements, three new radiometric calibration sites were selected in Dunhuang and Golmud. Obtaining high-resolution satellite image data of each calibration site and evaluating the spatial uniformity of the site on different spatial scales. The radiometric stability of the sites is evaluated using the long-term sequence of Landsat8 image data from 2013 to 2019. Atmospheric and surface tests were carried out at various sites in August 2019, and atmospheric information and ground spectral data were obtained to evaluate the spectral characteristics of the sites. The surface directional characteristics of the sites are evaluated by using MODIS images at different angles in sunny weather on adjacent dates. Obtaining MOD05 water vapor products from 2013 to 2019 of each calibration site and conducting monthly statistics. The number of sunny days at each calibration site is counted and the drought conditions of the site are evaluated. The results show that the three new radiometric calibration sites have uniform and stable surface characteristics and atmospheric characteristics, and are suitable for on-orbit radiometric calibration of satellite sensors, which provides a reference for the location and evaluation of future calibration sites.