中国空间辐射测量基准技术

In the demand of the quantitative use of satellite data, the accuracy of instrument calibration improved significantly because of the efforts of major satellite operators. However after decades of development, the current premium uncertainty of radiometric calibration of remote sensing satellites stays at 2% in visible, 0.5 k in infrared spectrum, due to the design restrains of on-board calibration devices, and also the theoretical limitation of vicarious techniques. Since the beginning of 21 st century, global climate change has become the common concern of international community. Global climate research placed an unprecedented need on the accuracy of radiometric calibration for remote sensing satellites. According to ASIC3 report, in order to detect climate change signals effectively and make accurate predictions, the acceptable uncertainty of radiometric calibration is 0.3% for solar reflective spectrum, 0.1 k for infrared spectrum, and 0.01% for total solar irradiance. Living up to the challenge, EU and US proposed TRUTHS and CLARREO plans, with the common goal of launching benchmark satellites. The benchmark satellites, with their extreme accuracy, designed to monitor climate change, could also calibrate other remote sensing satellites in orbit, raising the observation accuracy of the whole global satellite system to a new level. Meanwhile, China also advocated the concept of space radiometric observation benchmark system and launched two five-years projects to develop cutting-edge techniques such as phase-change warm load blackbody and on-orbit cryogenic absolute radiometer etc., aiming at establishing the absolute radiometric reference in space. With the support of these projects, the spaceborne SI-traceable calibrators for Reflective Solar Bands (RSBs) and Thermal Emissive Bands (TEBs) is developing. In the middle of the next five years, we can complete the development of the principle prototype of the radiometric benchmark instruments, and then achieve a comprehensive performance verification.Comparing to its counterparts, China could more likely become the first country to launch radiometric benchmark satellite, which leads remote sensing satellites to a SI-traceable era.