Feasibility of L-Band Sharpening With C-Band Using SMAP and AMSR Radiometry Data for Future Application to CIMR

Passive microwave remote sensing can provide direct and frequent measurements for the estimation of surface soil moisture globally. The future Copernicus Imaging Microwave Radiometer (CIMR) mission is projected to operate at five spectral bands, including L- and C-bands, providing a unique capability to observe surface soil moisture at multiple spatial resolutions. In this work, we investigate the potential to improve the coarser resolution of future CIMR L-band (<60 km) using finer resolution C-band (<15 km) by exploiting the overlap of band footprints. We use existing brightness temperature (TB) data from the Soil Moisture Active Passive (SMAP) mission and Advanced Microwave Scanning Radiometer 2 (AMSR2) mission to investigate L- and C-bands multiresolution information content at the global scale and assess the use of C-band information for L-band sharpening with a linear regression model. Comparing the performance of sharpened with true L-band TB, we find global improvements in systematic offset errors and time-varying random errors, especially along coastlines and over diverse vegetation land cover. Results support the conclusion that the C-band can capture information in the spatial enhancement of the L-band, demonstrating the value of future CIMR multifrequency observations to generate soil moisture products at both climatic and meteorological scales.