HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Free Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (8) Citing Articles via Google Scholar Google Scholar Articles by Schneeberger, K. Articles by Flühler, H. Search for Related Content PubMed Articles by Schneeberger, K. Articles by Flühler, H. GeoRef GeoRef Citation Agricola Articles by Schneeberger, K. Articles by Flühler, H. Related Collections Remote Sensing Vadose Zone Processes and Chemical Transport

SPECIAL SECTION: HYDROGEOPHYSICS

Topsoil Structure Influencing Soil Water Retrieval by Microwave Radiometry

^a Institute of Terrestrial Ecology, ETH Zurich, Grabenstrasse 11a, 8952 Schlieren, Switzerland
^b Institute of Terrestrial Ecology, ETH Zurich, Grabenstrasse 11a, 8952 Schlieren, Switzerland
^c EAWAG, Ueberlandstrasse 13, 8600 Duebendorf, Switzerland
^d Centre d'Etudes Spatiales et de la Biosphere (CESBIO) 18 av. Edouard Belin, bpi 2801, 31401 Toulouse Cedex 4, France
^e Institute of Applied Physics, University of Bern, Sidlerstrasse 5, 3012 Bern, Switzerland
^* Corresponding author (mike.schwank{at}env.ethz.ch)

Received 6 June 2004.

Many remote sensing applications, including those of future space missions, require accurate knowledge of the influence of topsoil structure on the water content as measured using L-band radiometry. We report on field-measured L-band (1.4 GHz) microwave emission from a bare soil. Of special interest in this work is the procedure used to transform remotely sensed data to soil water content and its comparability with time domain reflectometer (TDR) in situ measurements. Surface roughness of the soil was characterized on a millimeter scale using an optical measurement technique. Different models for interpreting the microwave signals in terms of the water content were investigated. The agreement between in situ water contents and surface water contents estimated with radiometry data using the Fresnel equation was found to be poor. A coherent layer model, with and without considering roughness effects, was tested to compare radiometrically measured and modeled soil reflectivities. The correspondence remained unsatisfactory, even when we considered a dielectric gradient fitted to the TDR profiles and surface roughness represented by a scattering model. We developed a new air-to-soil transition model, which includes dielectric mixing effects due to small-scale surface structures. This model considerably improved agreement between measured and modeled results. We conclude that small-scale structures of the topsoil cannot be neglected in interpreting L-band measurements.

Abbreviations: DSM, digital surface model • TDR, time-domain reflectometer

This article has been cited by other articles:

				D. A. Robinson, C. S. Campbell, J. W. Hopmans, B. K. Hornbuckle, S. B. Jones, R. Knight, F. Ogden, J. Selker, and O. Wendroth Soil Moisture Measurement for Ecological and Hydrological Watershed-Scale Observatories: A Review Vadose Zone J., February 25, 2008; 7(1): 358 - 389. [Abstract] [Full Text] [PDF]

				H. Vereecken, S. Hubbard, A. Binley, and T. Ferre Hydrogeophysics: An Introduction from the Guest Editors Vadose Zone J., November 1, 2004; 3(4): 1060 - 1062. [Full Text] [PDF]