气候变化领域集成服务门户(CCPortal): Soil moisture retrievals using ALOS2-ScanSAR and MODIS synergy over Tibetan Plateau

CCPortal

DOI	10.1016/j.rse.2020.112100
	Soil moisture retrievals using ALOS2-ScanSAR and MODIS synergy over Tibetan Plateau
	Wang H.; Magagi R.; Goïta K.; Wang K.
发表日期	2020
ISSN	00344257
卷号	251
英文摘要	This paper investigates the soil moisture retrievals over Tibetan Plateau using multi-temporal ALOS2-PALSAR2 data acquired in ScanSAR mode, in contrary to the commonly used StripMap SAR imaging mode. Considering the dual-polarimetry with limited observables, the surface roughness parameters such as the RMS height and auto-correlation length are first estimated by optimizing the semi-empirical Oh2004 model applied to the ALOS2 data acquired under bare soil condition. The vegetation water content corresponding to each ALOS2 acquisition time is derived from an empirical model applied to the temporally interpolated MODIS NDVI data. Then, the obtained roughness and vegetation optical depth are substituted into the Water Cloud Model which we modified by adding a double-bounce component according to the L-band scattering processes to retrieve the effective scattering albedo and soil moisture. The results show that the optimized surface RMS height and the associated slope are negatively related to a dual-angular radar index ΔHH, indicating the feasibility to optimize the relatively stable surface roughness parameters before retrieving the soil moisture dynamics. The obtained vegetation optical depth which is cross-validated against a normalized cross-polarized radar descriptor indicates a significant increase from May to August, in response to the vegetation phenological growth. Furthermore, the time-variable scattering albedo is less than 0.08, and slightly increases with the vegetation development. By accounting for the double-bounce component, the retrieved soil moisture better agrees with the ground measurements with R = 0.89 and RMSE = 0.058 m3/m3, but exhibits an overestimation issue for the soil moisture higher than 0.35 m3/m3 due to the saturation of SAR signal and the relatively strong vegetation cover. A positive correspondence (R = 0.81) between the retrieved soil moisture and the interpolated NDVI was found, verifying their close coupling in the soil-vegetation system. This study deepens the insights in the potential integration between the optical and L-band microwave observations to retrieve soil moisture over vegetated area. © 2020 Elsevier Inc.
英文关键词	ALOS2-PALSAR2; Radiative transfer model; ScanSAR mode; Soil moisture; Tibetan plateau
语种	英语
scopus关键词	Optical properties; Radiometers; Soil moisture; Solar radiation; Surface roughness; Synthetic aperture radar; Vegetation; Ground measurements; Microwave observations; Soil moisture dynamics; Soil moisture retrievals; Surface roughness parameters; Vegetation optical depth; Vegetation water content; Water cloud models; Soil surveys; albedo; ALOS; MODIS; NDVI; optical depth; phenology; soil moisture; surface roughness; synergism; synthetic aperture radar; vegetation cover; water content; China; Qinghai-Xizang Plateau
来源期刊	Remote Sensing of Environment
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/179113
作者单位	College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, China; Centre d'Applications et de Recherches en Télédétection (CARTEL), Département de Géomatique Appliquée, Université de Sherbrooke, Sherbrook, QC J1K 2R1, Canada
推荐引用方式 GB/T 7714	Wang H.,Magagi R.,Goïta K.,et al. Soil moisture retrievals using ALOS2-ScanSAR and MODIS synergy over Tibetan Plateau[J],2020,251.
APA	Wang H.,Magagi R.,Goïta K.,&Wang K..(2020).Soil moisture retrievals using ALOS2-ScanSAR and MODIS synergy over Tibetan Plateau.Remote Sensing of Environment,251.
MLA	Wang H.,et al."Soil moisture retrievals using ALOS2-ScanSAR and MODIS synergy over Tibetan Plateau".Remote Sensing of Environment 251(2020).