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DOI	10.1016/j.rse.2020.112019
	A temporal polarization ratio algorithm for calibration-free retrieval of soil moisture at L-band
	Gao L.; Sadeghi M.; Ebtehaj A.; Wigneron J.-P.
发表日期	2020
ISSN	00344257
卷号	249
英文摘要	Monitoring of surface soil moisture (SM) through microwave radiometry typically relies on the inversion of a radiative transfer model. Conventional inversion algorithms require proper calibration of surface roughness and radiometric parameters of the overlying canopy, including the scattering albedo and optical depth. However, uncertainty in global characterization of these parameters is one of the main sources of error in satellite SM retrievals. To cope with this uncertainty, this paper presents a new algorithm, called “temporal polarization ratio algorithm” (TPRA), that enables retrieval of SM independent of surface roughness and vegetation parameters. This approach uses the temporal differences of polarized emissivity observations assuming that the surface roughness and vegetation parameters are invariant over a window of time. Unlike the classical dual channel algorithms (DCA), TPRA is not only free of surface calibration but also robust to systematical errors arising from surface soil temperature errors. One caveat is that the algorithm is unable to retrieve SM when surface emissivity does not change appreciably in time. The performance of TPRA is evaluated through several controlled numerical experiments and validated using the Soil Moisture Active Passive (SMAP) satellite retrievals as well as in-situ SM measurements over Australia. The results show improved SM retrievals compared with the DCA and SMAP official products as long as the surface emissivity changes sufficiently over the retrieval time period. © 2020 Elsevier Inc.
英文关键词	Calibration free; L-band radiometry; Soil moisture
语种	英语
scopus关键词	Calibration; Electromagnetic wave emission; Errors; Parameter estimation; Polarization; Radiative transfer; Radiometry; Soil moisture; Vegetation; Microwave radiometry; Numerical experiments; Polarized emissivity; Radiative transfer model; Soil moisture active passive (SMAP); Surface soil moisture; Surface soil temperatures; Vegetation parameters; Surface roughness; albedo; algorithm; calibration; polarization; radiative transfer; radiometric method; satellite altimetry; soil moisture; temporal variation; uncertainty analysis; Australia
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/179174
作者单位	Saint Anthony Falls Laboratory, Department of Civil Environmental and Geo-Engineering, University of Minnesota, Minneapolis, MN 55414, United States; INRA, UMR1391 ISPA, F-33140, Villenave d'Ornon, France
推荐引用方式 GB/T 7714	Gao L.,Sadeghi M.,Ebtehaj A.,et al. A temporal polarization ratio algorithm for calibration-free retrieval of soil moisture at L-band[J],2020,249.
APA	Gao L.,Sadeghi M.,Ebtehaj A.,&Wigneron J.-P..(2020).A temporal polarization ratio algorithm for calibration-free retrieval of soil moisture at L-band.Remote Sensing of Environment,249.
MLA	Gao L.,et al."A temporal polarization ratio algorithm for calibration-free retrieval of soil moisture at L-band".Remote Sensing of Environment 249(2020).