On-Orbit Performance Analysis of AIUS/GF-5 Instrument

GF-5 is a hyperspectral remote sensing satellite in the GF series of satellite of China, which was successfully launched on 9 May 2018. The key instrument, the Atmospheric Infrared Ultra-spectral Sounder (AIUS), is the first space-borne occultation sensor with ultra-spectral resolution in China, as well as the space-borne Fourier transform spectrometer (FTS) with finest spectral resolution. The instrument covers wavelengths from 2.4 to 13.3 μm, providing the ultra-spectral resolution with 0.03 cm−1. The AIUS instrument will measure trace gases in the atmosphere and analyse the chemical and dynamical processes by solar occultation from GF-5 satellite. This paper describes the on-orbit test activities and performances of key characteristics, including Signal-to-Noise Ratio (SNR), accuracy of spectral calibration and spectral resolution based on the on-orbit data obtained. The preliminary results from the on-orbit verification, calibration and validation after launch have shown that AIUS has good performance with good quality spectrum. The results show that the SNR will meet the requirement, the full width at half maximum (FWHM) will be smaller than 0.03 cm−1 and the accuracy of spectral calibration will be greater than 0.008 cm−1. The AIUS instrument on-board GF5 satellite will provide fine spectral transmittances of the atmosphere and offer the best atmospheric constituents observing performance in solar occultation.