Improving the Spatial Resolution of FY-3 Microwave Radiation Imager via Fusion With FY-3/MERSI

This paper proposes an effective approach to improve the spatial resolution of FengYun-3 (FY-3) microwave radiation imager (MWRI) data via fusing with FY-3 medium-resolution imager (MERSI) data. Located onboard the same satellite FY-3, the complementary properties of MWRI and MERSI, such as cloud-penetrating ability and high spatial resolution, are explored to extend the applications of MWRI data to mesoscale or microscale. To this end, we make efforts to improve the spatial resolution of MWRI data by combining the spatial information and spectral information from MERSI and MWRI, respectively. The proposed fusion procedure includes two stages. In the first stage, the MERSI and MWRI images are jointly spectrally unmixed via learning a spectral dictionary pair, and then the spatial information from MERSI is transferred into MWRI by sparse coding, resulting in a spatial resolution enhanced MWRI image. In the second stage, the spectral information of the spatial resolution enhanced MWRI image is enhanced through guided filtering. To form a unified fusion framework for both the cloud-free and cloud-contaminated cases in MERSI images, we propose to leverage a learning-based single image super-resolution method in the cloud-contaminated case, which learns a spatial dictionary pair from the MWRI image pairs of low and high spatial resolutions obtained in the cloud-free case. To the best of our knowledge, the proposed method is the first fusion based one for spatial resolution enhancement of microwave radiometer images. Finally, to assess the performance of the proposed fusion framework, we choose three MERSI-MWRI image pairs to evaluate in both the cloud-free and cloud-contaminated cases. Both visual comparisons and quantitative evaluations validate the effectiveness of the proposed fusion method in preserving the spatial information of MERSI and the spectral information of MWRI. Comparisons with a state-of-the-art method that does not resort to optical data, demonstrate the superiority of the pro-posed method with better overall measurements for experimental results.