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Temporal Stability of Soil Moisture and Radar Backscatter Observed by the Advanced Synthetic Aperture Radar (ASAR)

View Article: PubMed Central - PubMed

ABSTRACT

The high spatio-temporal variability of soil moisture is the result of atmospheric forcing and redistribution processes related to terrain, soil, and vegetation characteristics. Despite this high variability, many field studies have shown that in the temporal domain soil moisture measured at specific locations is correlated to the mean soil moisture content over an area. Since the measurements taken by Synthetic Aperture Radar (SAR) instruments are very sensitive to soil moisture it is hypothesized that the temporally stable soil moisture patterns are reflected in the radar backscatter measurements. To verify this hypothesis 73 Wide Swath (WS) images have been acquired by the ENVISAT Advanced Synthetic Aperture Radar (ASAR) over the REMEDHUS soil moisture network located in the Duero basin, Spain. It is found that a time-invariant linear relationship is well suited for relating local scale (pixel) and regional scale (50 km) backscatter. The observed linear model coefficients can be estimated by considering the scattering properties of the terrain and vegetation and the soil moisture scaling properties. For both linear model coefficients, the relative error between observed and modelled values is less than 5 % and the coefficient of determination (R2) is 86 %. The results are of relevance for interpreting and downscaling coarse resolution soil moisture data retrieved from active (METOP ASCAT) and passive (SMOS, AMSR-E) instruments.

No MeSH data available.


Study area. The left map shows the land cover and location of the in-situ soil moisture stations within the REMEDHUS network located in the Duero Basin, Spain. The right map shows a false-colour Landsat image (bands 4, 3, 2) of the area.
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f1-sensors-08-01174: Study area. The left map shows the land cover and location of the in-situ soil moisture stations within the REMEDHUS network located in the Duero Basin, Spain. The right map shows a false-colour Landsat image (bands 4, 3, 2) of the area.

Mentions: The test site is a region of 4200 km2 that surrounds the 1285 km2 REMEDHUS network area located in the centre of the Duero basin, Spain, where the University of Salamanca has been operating in-situ soil moisture stations since 1999 (Figure 1) [39].


Temporal Stability of Soil Moisture and Radar Backscatter Observed by the Advanced Synthetic Aperture Radar (ASAR)
Study area. The left map shows the land cover and location of the in-situ soil moisture stations within the REMEDHUS network located in the Duero Basin, Spain. The right map shows a false-colour Landsat image (bands 4, 3, 2) of the area.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3927501&req=5

f1-sensors-08-01174: Study area. The left map shows the land cover and location of the in-situ soil moisture stations within the REMEDHUS network located in the Duero Basin, Spain. The right map shows a false-colour Landsat image (bands 4, 3, 2) of the area.
Mentions: The test site is a region of 4200 km2 that surrounds the 1285 km2 REMEDHUS network area located in the centre of the Duero basin, Spain, where the University of Salamanca has been operating in-situ soil moisture stations since 1999 (Figure 1) [39].

View Article: PubMed Central - PubMed

ABSTRACT

The high spatio-temporal variability of soil moisture is the result of atmospheric forcing and redistribution processes related to terrain, soil, and vegetation characteristics. Despite this high variability, many field studies have shown that in the temporal domain soil moisture measured at specific locations is correlated to the mean soil moisture content over an area. Since the measurements taken by Synthetic Aperture Radar (SAR) instruments are very sensitive to soil moisture it is hypothesized that the temporally stable soil moisture patterns are reflected in the radar backscatter measurements. To verify this hypothesis 73 Wide Swath (WS) images have been acquired by the ENVISAT Advanced Synthetic Aperture Radar (ASAR) over the REMEDHUS soil moisture network located in the Duero basin, Spain. It is found that a time-invariant linear relationship is well suited for relating local scale (pixel) and regional scale (50 km) backscatter. The observed linear model coefficients can be estimated by considering the scattering properties of the terrain and vegetation and the soil moisture scaling properties. For both linear model coefficients, the relative error between observed and modelled values is less than 5 % and the coefficient of determination (R2) is 86 %. The results are of relevance for interpreting and downscaling coarse resolution soil moisture data retrieved from active (METOP ASCAT) and passive (SMOS, AMSR-E) instruments.

No MeSH data available.