Investigation of optical environment changes in the Dunhuang gobi site of the Chinese radiometric calibration sites

In order to effectively evaluate the influence of scattered radiation of the heat collection tower on the optical environment of the Dunhuang Gobi Site of the Chinese Radiometric Calibration Sites (CRCS), the Monte Carlo three-dimensional radiation transmission model simulation combined with in situ CE318 multi-channel photometer almucantar measurements was applied to solve the problem that it is difficult to quantitatively evaluate the scattered radiation mixed with the background radiation. By measuring the data with a new cloud cover automatic observing instrument ASC200, the accuracy of clear sky measurements improved, and the development of the CE318 four-quadrant location correction algorithm effectively increased the amount of valid data that meets our threshold requirements. The effective data collected from January to March 2020 shows that the molten salt tower Concentrating Solar Power (CSP) project has no significant impact on the sky diffuse radiation outside the 550nm channel. In the 500 nm channel, under the geometric parameters corresponding to the valid data (distance 0.87−3.07 km, observation zenith angle 77.30−51.32º), the impact of the molten salt tower heat absorber on diffuse sky radiation does not exceed 0.93%. Combined with the analysis of the model simulation results, it can be concluded that the relative change of the sky diffuse radiation caused by the scattered radiation of the large power station is less than 1.62% at 2 km away, and the relative change is less than 0.93% when it is at least 3 km away. The research results have positive significance for the use of Dunhuang Site to conduct quantitative applications in remote sensing and the accurate evaluation of the uncertainties introduced by power stations.