### Evaluating effects of Dielectric Models on the surface soil moisture retrieval in the Qinghai-Tibet Plateau

Rong Liu1(),Xin Wang1,ZuoLiang Wang1,Jun Wen2

1. 1.Key Laboratory of Land Surface Process and Climate Change in Cold and Arid Regions, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, Gansu 730000, China
2.College of Atmospheric Sciences, Chengdu university of Information Technology, Chengdu, Sichuan 610225, China
• Received:2020-07-09 Accepted:2020-12-01 Online:2021-02-28 Published:2021-02-07
• Contact: Rong Liu E-mail:rliu@lzb.ac.cn
• Supported by:
the National Science Foundation of China(42075065);the Second Tibetan Plateau Scientific Expedition and Research (STEP) program(2019QZKK0105)

Abstract:

Based on the measurement of L-band ground-based microwave radiometer (ELBARA-III type) in the Qinghai-Tibet Plateau and the $τ-ω$ radiative transfer model, this research evaluated the effects of four soil dielectric models, i.e., Wang-Schmugge, Mironov, Dobson, and Four-phase, on the L-band microwave brightness temperature simulation and soil moisture retrieval. The results show that with the same vegetation and roughness parameterization scheme, the four soil dielectric models display obvious differences in microwave brightness temperature simulation. When the soil moisture is less than 0.23 m3/m3, the simulated microwave brightness temperature in Wang-Schmugge model is significantly different from that of the other three models, with maximum differences of horizontal polarization and vertical polarization reaching 8.0 K and 4.4 K, respectively; when the soil moisture is greater than 0.23 m3/m3, the simulated microwave brightness temperature of Four-phase significantly exceeds that of the other three models; when the soil moisture is saturated, maximum differences in simulated microwave brightness temperature with horizontal polarization and vertical polarization are 6.1 K and 4.8 K respectively, and the four soil dielectric models are more variable in the microwave brightness temperature simulation with horizontal polarization than that with vertical polarization. As for the soil moisture retrieval based on the four dielectric models, the comparison study shows that, under the condition of horizontal polarization, Wang-Schmugge model can reduce the degree of retrieved soil moisture underestimating the observed soil moisture more effectively than other parameterization schemes, while under the condition of vertical polarization, the Mironov model can reduce the degree of retrieved soil moisture overestimating the observed soil moisture. Finally, based on the Wang-Schmugge model and FengYun-3C observation data, the spatial distribution of soil moisture in the study area is retrieved.