Consistency transfer calibration method for MERSI solar reflection bands of FY-3 series

The Medium Resolution Spectral Imager (MERSI) provides a global, long-term, and consistent time series of data with favorable spectral and spatial resolution that are essential for climate change studies. However, two independent sources of early MERSI data revealed significant calibration issues: the absence of reliable onboard calibration and the presence of trends and biases in MERSI radiance relative to other accurate sources of top-of-atmosphere (TOA) radiance. This study tracked the degradation of solar reflective bands on the FY-3 MERSI by integrating matched sample data from multiple calibration methods. By applying a degradation-fusion recalibration approach, a high-precision reference payload FY-3A MERSI was established for the FY-3 satellite series. Using overlapping observations over a stable Libya 4 Desert site, a radiometric consistency transfer model between FY-3A and FY-3B MERSI was constructed, enabling consistency transfer calibration of FY-3B MERSI. This approach addressed the issue of inconsistent MERSI observational data across different FY-3 satellites and achieved radiometric consistency across domestically produced multi-satellite systems. The results showed that the uncertainties in radiometric consistency transfer models for all channels (except for channels 17, 18, and 19) remained within 6%, demonstrating high reliability.