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Soil Parameter Retrieval under Vegetation Cover Using SAR Polarimetry

Jagdhuber, Thomas (2012) Soil Parameter Retrieval under Vegetation Cover Using SAR Polarimetry. Dissertation, University of Potsdam.

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Official URL: http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-60519

Abstract

Soil conditions under vegetation cover and their spatial and temporal variations from point to catchment scale are crucial for understanding hydrological processes within the vadose zone, for managing irrigation and consequently maximizing yield by precision farming. Soil moisture and soil roughness are the key parameters that characterize the soil status. In order to monitor their spatial and temporal variability on large scales, remote sensing techniques are required. Therefore the determination of soil parameters under vegetation cover was approached in this thesis by means of (multi-angular) polarimetric SAR acquisitions at a longer wavelength (L-band, lambda=23cm). In this thesis, the penetration capabilities of L-band are combined with newly developed (multi-angular) polarimetric decomposition techniques to separate the different scattering contributions, which are occurring in vegetation and on ground. Subsequently the ground components are inverted to estimate the soil characteristics. The novel (multi-angular) polarimetric decomposition techniques for soil parameter retrieval are physically-based, computationally inexpensive and can be solved analytically without any a priori knowledge. Therefore they can be applied without test site calibration directly to agricultural areas. The developed algorithms are validated with fully polarimetric SAR data acquired by the airborne E-SAR sensor of the German Aerospace Center (DLR) for three different study areas in Germany. The achieved results reveal inversion rates up to 99% for the soil moisture and soil roughness retrieval in agricultural areas. However, in forested areas the inversion rate drops significantly for most of the algorithms, because the inversion in forests is invalid for the applied scattering models at L-band. The validation against simultaneously acquired field measurements indicates an estimation accuracy (root mean square error) of 5-10vol.% for the soil moisture (range of in situ values: 1-46vol.%) and of 0.37-0.45cm for the soil roughness (range of in situ values: 0.5-4.0cm) within the catchment. Hence, a continuous monitoring of soil parameters with the obtained precision, excluding frozen and snow covered conditions, is possible. Especially future, fully polarimetric, space-borne, long wavelength SAR missions can profit distinctively from the developed polarimetric decomposition techniques for separation of ground and volume contributions as well as for soil parameter retrieval on large spatial scales.

Document Type:Thesis (Dissertation)
Title:Soil Parameter Retrieval under Vegetation Cover Using SAR Polarimetry
Authors:
AuthorsInstitution or Email of Authors
Jagdhuber, ThomasUNSPECIFIED
Date:7 July 2012
Refereed publication:Yes
Number of Pages:236
Status:Published
Keywords:SAR, Polarimetry, Polarimetric SAR, Soil Moisture, soil roughness, decompositions, vegetation cover, multi-angular decompositions, polarimetric decompositions, active remote sensing
Institution:University of Potsdam
Department:Faculty of Mathematics and Natural Sciences
HGF - Research field:Aeronautics, Space and Transport (old)
HGF - Program:Space (old)
HGF - Program Themes:W EO - Erdbeobachtung
DLR - Research area:Space
DLR - Program:W EO - Erdbeobachtung
DLR - Research theme (Project):W - Vorhaben Prosmart, Smart-SAR (old)
Location: Oberpfaffenhofen
Institutes and Institutions:Microwaves and Radar Institute > Radar Concepts
Deposited By: Thomas Jagdhuber
Deposited On:18 Jul 2012 10:03
Last Modified:10 Mar 2014 16:13

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