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The extensive field data base of the TERENO project is utilized to validate inversion results for soil moisture under vegetation within two terrestrial observatories (Central German Lowland Observatory and Lower Rhine Valley Observatory). The recently developed hybrid decomposition and inversion approach is applied to L-band fully polarimetric SAR data acquired within the TERENO campaign of 2011 by DLR's novel high resolution F-SAR sensor in order to investigate its potential. The soil moisture results state a spatially continuous inversion under vegetation with a RMSE between 3.2vol.% and 8.2vol.% for both observatories. Therefore the results are particularly suited for local analyses on the field level in contrast to soil moisture products with low resolution from passive microwave sensors on the catchment level. [ABSTRACT FROM PUBLISHER]

A correction method for distortions induced by ionospheric scintillation effects on P-band quad-pol synthetic aperture radar (SAR) data acquired in polar and high latitude regions is presented. For this the estimation of the Faraday rotation (FR) is converted to ionospheric phase and used for the correction of the scintillation. The correction is performed on partially focused SLC data in order to compensate the ionosphere-induced phase and the distortion of the time-Doppler history. The degree of defocusing depends on the altitude of the ionosphere. The performance of the new correction method is tested on P-band simulated data for various ionospheric scenarios. [ABSTRACT FROM PUBLISHER]

The identification of scatterers having a point-like behavior in SAR images has become an important topic with a wide range of applications, from calibration to information extraction. So far, three different approaches are available for the Coherent Scatterer (CS) detection, based on spectral correlation techniques using only a single SAR image. In this paper, a new approach based on the generalized likelihood ratio test (GLRT) is introduced. An extensive performance analysis using the different detection methods is presented, comparing the new proposed method with the previous ones. Lastly, the new approach is tested using real data. [ABSTRACT FROM PUBLISHER]

Soil moisture retrieval under agricultural vegetation is assessed by a hybrid decomposition and inversion algorithm using fully polarimetric SAR data of DLR's E-SAR system at L-band. The results for the AgriSAR and SARTEO campaigns, conducted in 2006 and 2008 within the Peene and the Rur catchment, reveal a very high inversion rate leading to a spatially continuous inversion along the entire growth cycle in agricultural areas. The validation with in situ measurements for a variety of summer and winter crops states a root mean square error of 6.25vol.% and 5.77vol.% respectively, while a wide moisture range (∼2–30vol.%) is covered by the soil moisture inversion under vegetation. [ABSTRACT FROM PUBLISHER]

In recent years an increased interest arose in using synthetic aperture radar (SAR) to study and monitor land ice for glaciological applications and climate change research. At long wavelengths, SAR systems can penetrate into glacier ice for several tens to hundreds of meters. This makes them sensitive to near-surface as well as deeper ice volume features. This paper investigates the performance of a volume scattering component, in the course of an electromagnetic (e.m.) model development, to relate Polarimetric SAR (PolSAR) signatures to glacier facie. Indeed, PolSAR ice signatures are still poorly understood, including the importance of scattering from the glacier ice volume and its dependency on frequency and incidence angle. A comparison is performed with airborne Pol-SAR data at L- and P-band collected by DLR's E-SAR system over the Austfonna ice cap in Svalbard, Norway, within the ICESAR campaign. [ABSTRACT FROM PUBLISHER]

A validation method for polarimetric SAR model-based decompositions is proposed based on correlation coefficients between polarizations. The correlation coefficient is examined if it ranges from 0 to 1 for covariance matrices after the subtraction of volumetric scattering components. The three combinations of the polarizations seen in covariance matrices are examined. It is confirmed that, in general, the condition above is not held, which clarifies the overestimate of volume scattering, even though conventional procedures take negative powers into account. Furthermore, the possible maximal power of volume scattering is estimated by employing the condition as a constraint. The constraint by correlation coefficients is a part of the one by nonnegative eigenvalues. In order to equalize them, the third-order principal minor, that is the determinant in the case of 3*3 matrices, must be considered. Finally, the possible maximal power, equal to the one derived from the constraint by nonnegative eigenvalues, can be derived analytically, while that is estimated numerically for the case of nonnegative eigenvalues. [ABSTRACT FROM PUBLISHER]