Simulation of A Combined Passive/active Microwave Remote Sensing Approach for Soil Moisture Retrieval

摘要

From 1997 to 1998, the GEWEX(Global Energy and Water cycle Experiment) / GAME(GEWEX related Asian Monsoon Experiment)-Tibet was held on Tibetan Plateau. At the same time, the Tropical Rainfall Measuring Mission (TRMM) satellite’s measurement could cover the whole experiment field. How to employs the active (precipitation radar, PR) and passive (TRMM Microwave Imager, TMI) microwave remote sensing data to the soil moisture retrieval is an interesting question. This study is not just a case study on TRMM’s sensors; it could be apply to any combined active/passive remote sensing platform which could cover The Tibetan Plateau. In this paper, we present a simple method to improve the spatial resolution of soil moisture retrieval result using the combined active/passive data. The base of the retrieval algorithm is: first, the surface roughness keeps stabile in several months and second, the soil moisture within the passive footprint over Tibetan Plateau in Mar is uniformly (this is because before the rain season, the soil moisture in Tibetan Plateau is dominated by soil thaw, and the thaw process is dominated by temperature which is uniform in the TMI footprint). Firstly, we test the simple scattering model (SSM) under the parameters of TRMM/PR, and secondly we do the numerical simulation of the combined algorithm. The result is pretty good; most of the error is below 2%.