Remote Sensing Technology and Application, Volume. 40, Issue 3, 610(2025)
A Radiation Reference Transfer Method based on Hyperspectral Measurements on Geostationary Orbit
Considering that the Geosynchronous Interferometric Infrared Sounder (FY-4A/GIIRS) has high spectral and radiometric calibration accuracy and operates on Geostationary orbit (GEO), GIIRS can provide higher temporal frequency radiometric comparisons of other broad-band infrared remote sensors including those in Low-Earth orbit (LEO) and GEO to monitor the intraday variation of their radiometric performance. Therefore, based on the inter-calibration baseline algorithm issued by the Global Space-based Inter-Calibration System (GSICS), a method for radiometric reference transfer with GIIRS as the reference sensor is established. This method defines inter-calibration conditions and thresholds suitable for different platform instruments between LEO-GEO and GEO-GEO, based on the characteristics of high observation frequency but low spatial resolution of GEO sensor, which can support inter-calibration with higher time frequency and larger regional scope. It is shown through the radiometric reference transfer of the Advanced Geosynchronous Radiation Image (FY-4A/AGRI) that, it is feasible to use GIIRS for radiometric reference transfer, and the collocated results of long-wave infrared band (10.3~11.3 μm) have a good fitting relationship in most times. The brightness (BT) deviation of AGRI relative to GIIRS is increased because of too few sampling points. After removing the result of too few points (less than 1 000), the average absolute BT deviation is 1.2 K@290 K, which is 0.7 K lower. The BT deviation fluctuates slightly at odd times and greatly at even times. The main reason is that the GIIRS observation area at odd times is in low latitudes (10°~30°N), while it is in middle and high latitudes (30°~60°N) at even times. As the latitude rises, the spatial collocation error increases and relatively uniform collocated pixels decreases significantly with the footprint distortion increases. In order to reduce the error, when calculating the radiance of the target area, it should be variably weighted (instead of uniformly weighted) according to the relative positions of the pixels, so as to improve the collocation accuracy when GIIRS is used as a reference remote sensor.
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Qiang GUO, Yuning LIU, Xin WANG, Wen HUI. A Radiation Reference Transfer Method based on Hyperspectral Measurements on Geostationary Orbit[J]. Remote Sensing Technology and Application, 2025, 40(3): 610
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Received: Jan. 25, 2024
Accepted: --
Published Online: Sep. 28, 2025
The Author Email: Xin WANG (xinwang@cma.gov.cn)