Estimation of soil moisture from multi-polarized SAR data over wheat coverage areas

Abstract

Radar data has important implications in agricultural fields monitoring, particularly in the retrieval of the crop height, leaf area index (LAI) and soil moisture information. The objective of this study was to estimate soil moisture contents based on multi-polarized synthetic aperture radar (SAR) data acquired over wheat fields. The soil moisture inversion algorithm was based on semi-empirical backscattering models and the prior estimation of wheat heights ( h ) and wheat water contents ( WC ) from SAR data(RADARSAT-2). The co-polarized correlation coefficient ( vvhh ρ ) and the ratio of the absolute value of the cross polarization to the crop height ( vh Λ ) were analyzed with respect to variations in wheat height and wheat water content. The results showed average relative errors of 14%, 32% and 24% for the retrieval of wheat height, wheat water content and soil moisture, respectively.

Coupling SAR C-Band and Optical Data for Soil Moisture and Leaf Area Index Retrieval Over Irrigated Grasslands

“…The study site was a 450 hectare farmland composed of irrigated and non-irrigated grassland for hay in : IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, n° 99, 2015. p. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] production. Located in southeastern France (center: 43.64°N, 5.01°E, Figure 1), this relatively flat site is characterized by a Mediterranean climate, with a rainy season between September and November and an average cumulative rainfall between 350 mm and 800 mm [23].…”

“…Recently, Betbeder et al [45] showed that the Shannon entropy is highly correlated with the fragmentation of hedgerows. The Pauli decomposition components corresponding to the three diagonal in : IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, n° 99, 2015. p. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] elements of the coherency matrix ( [46]), each have a specific scattering mechanism: (HH+VV) represents the surface scattering, (HV+VH) is associated with volume scattering, and (HH-VV) indicates doublebounce scattering. Surface scattering dominates when the radar signal is primarily reflected from the canopy top.…”

Soil moisture retrieval over irrigated grassland using X-band SAR data

“…These results encourage the use of X-band with medium angle (about 30°) in both HH and HV polarizations for soil moisture estimates over grassland. For C and X-bands SAR data, studies showed that it is possible to estimate the soil moisture with accuracy from 2 to 8 Vol.% (RMSE "Root Mean Square Error") (Gherboudj et al, 2011;He et al, 2014;Notarnicola et al, 2006;Prévot et al, 1993;Sikdar and Cumming, 2004;Wang et al, 2011;Yang et al, 2012;Yu and Zhao, 2011;Zribi et al, 2011).…”

Synergic Use of Sentinel-1 and Sentinel-2 Images for Operational Soil Moisture Mapping at High Spatial Resolution over Agricultural Areas

“…The WCM is the most commonly used model to estimate soil moisture in the presence of vegetation cover because it uses a simple formulation and consequently, it could be easily inverted [21,29,[31][32][33][45][46][47][48]. In the WCM, the total backscattered signal is equal to the sum of vegetation contribution and soil contribution attenuated by the vegetation layer.…”