Retrievals of soil moisture and vegetation optical depth using a multi-channel collaborative algorithm

• DOI: 10.1016/j.rse.2021.112321
• Publication Date: 2021-02-22T22:19:16Z
• Authors: Tianjie Zhao; Jiancheng Shi; Dara Entekhabi; Thomas J. Jackson; Lu Hu; Zhiqing Peng; Panpan Yao; Shangnan Li; Chuen Siang Kang
• Keywords: Radiometry; Microwave radiometer; Scatterometer

Due to the success of SMOS (Soil Moisture and Ocean Salinity) SMAP Active Passive) missions, new satellite missions are on horizon. The current future can benefit from investigations that seek improve retrieval algorithms quantitatively map global soil moisture vegetation optical depth (tau) Earth's microwave emissions. In this study, we explore multi-angular multi-frequency approaches for tau, considering payload configurations (such as Copernicus Imaging Microwave Radiometer, Water Cycle Observation Mission, Terrestrial Resources Satellite) using a set ground observations. Two ground-based radiometry datasets collected in Inner Mongolia during Soil Experiment Luan River July August 2017 (cropland) September 2018 (grassland) used study. corn field, which covers an entire growth period, indicated degree information increases linearly number channels (in terms incidence angle frequency) increases, observations contain slightly more independent than do under same channels. polarization difference brightness temperature is sensitive both water content, especially at L-band due its penetrating ability. explains most variance frequency differences adjacent frequencies (L- & C-bands, C- X-bands), while incidence-angle mostly associated with content. A multi-channel collaborative algorithm (MCCA) developed based two-component version omega-tau model, utilizes expressed analytical form core channel rule out parameters be retrieved. Results show approach by MCCA generally has better performance, unbiased root mean square (ubRMSD) varying 0.028 cm3/cm3 0.037 cm3/cm3, (ubRMSD 0.089 cm3/cm3) field. This attributed dependence tau being significant angle. Except X-band combination, performs 0.018 0.023 0.026 0.034 grass field reduced effects type cover. It affirmed increasing observation could make robust, but might also limit probability model estimations will not match increased. study provides insights into design potential retrieval. simultaneous capabilities highly recommended.