An evaluation of the temporal stability of HJ-1 CCD data using a desert calibration site and Landsat 7 ETM+

Remote-sensing data from the China Huan Jing 1 charge-coupled device (HJ-1 CCD) sensors have been extensively used to capture the dynamics of the Earth's resources and environment, and to complement Landsat observations. It is critical to obtain radiometrically continuous and consistent measurements from multiple instruments spanning various periods. This study evaluated the radiometric stability of the HJ-1 CCD sensors since launch based on the stable Dunhuang calibration site and the Landsat Enhanced Thematic Mapper Plus (ETM+). The top-of-atmosphere (TOA) reflectance trends revealed from all rigorous selected cloud-free images showed that all bands of the CCD sensors degraded with time ranging from 1% to 7% per year, with the near-infrared (NIR) bands exhibiting the greatest drift. In addition, comparisons between the simultaneous HJ-1 CCD and Landsat ETM+ data revealed that the HJ-1 CCD agreed with the ETM+ within 3% for blue, green, and red bands after adjustment for spectral differences, whereas the NIR bands exhibited larger uncertainties at the level of 4%. The results provided comprehensive analysis of the long-term radiometric performance of the HJ-1 CCD sensors, which will serve as a reference for further applications using HJ-1 CCD data, as well as for successor missions of Chinese satellites, e.g. the Gaofen (GF) series of Earth observation satellites.