Article (Scientific journals)
A dielectric mixing model accounting for soil organic matter
Park, C.-H.; Montzka, C.; Jagdhuber, T. et al.
2019In Vadose Zone Journal, 18 (1)
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Keywords :
Biogeochemistry; Microwave sensors; Microwaves; Mixing; Moisture control; Organic compounds; Permittivity; Reflectometers; Salinity measurement; Advanced microwave scanning radiometer; Effective dielectric constants; Microwave radiative transfer model; Passive microwave sensors; Soil moisture active passive (SMAP); Soil Moisture and Ocean Salinity (SMOS); Surface soil moisture retrieval; Time-domain reflectometers; Soil moisture; AMSR-E; SMOS
Abstract :
[en] Most dielectric mixing models have been developed for mineral soils without extensive consideration of organic matter (OM). In addition, when used for in situ measurement, most of these models focus only on the real part of the effective dielectric constant without the corresponding imaginary part. Organic matter fractions in soils are found globally (57%), with an especially significant amount in the boreal region (17%). Without proper consideration of OM in dielectric mixing models and subsequent microwave radiative transfer modeling, brightness temperature (TB) calculations may be erroneous. This would lead to uncertainties in the estimation of higher level products, such as soil moisture retrievals from portable soil moisture sensors (e.g., time-domain reflectometers) or passive microwave sensors onboard the Soil Moisture Active Passive (SMAP), Soil Moisture and Ocean Salinity (SMOS), and Advanced Microwave Scanning Radiometer (AMSR2) satellites. We incorporated OM into a dielectric mixing model by adjusting the wilting point and porosity according to the OM content, i.e., the effective soil dielectric constant decreases with higher OM due to a decrease in the fraction of free water and an increase in bound water. With the proposed soil parameters in the dielectric mixing model, high levels of OM increase the TB for a specific soil moisture by decreasing the microwave effective dielectric constant. The simulated TB better reproduced SMAP-observed TB (11% in RMSE) through the improvement of the effective dielectric constant (40% reduction in RMSE). We anticipate that the application of our approach can improve microwave-based surface soil moisture retrievals in areas with high OM. © 2019 The Author(s).
Disciplines :
Earth sciences & physical geography
Environmental sciences & ecology
Author, co-author :
Park, C.-H.;  National Institute of Meteorological Sciences, Earth System Research Division, Korea Meteorological Administration (KMA), Jeju, South Korea
Montzka, C.;  Forschungszentrum Jülich GmbH, Institute of Bio-and Geosciences: Agrosphere (IBG-3), Jülich, 52428, Germany
Jagdhuber, T.;  Microwaves and Radar Institute, German Aerospace Center (DLR), Weßling, 82234, Germany
Jonard, François  ;  Université de Liège - ULiège > Département de géographie > Systèmes d'information géographiques
De Lannoy, G.;  Dep. of Earth and Environmental Sciences, KU Leuven, Heverlee, B-3001, Belgium
Hong, J.;  Ecosystem-Atmosphere Process Lab., Dep. of Atmospheric Science, Yonsei Univ., Seoul, 03722, South Korea
Jackson, T. J.;  Hydrology and Remote Sensing Lab., USDA, Beltsville Agricultural Research Center, Beltsville, MD 20705, United States
Wulfmeyer, V.;  Institute of Physics and Meteorology, Univ. of Hohenheim, Stuttgart, 70599, Germany
Language :
English
Title :
A dielectric mixing model accounting for soil organic matter
Publication date :
2019
Journal title :
Vadose Zone Journal
ISSN :
1539-1663
Publisher :
Soil Science Society of America
Volume :
18
Issue :
1
Peer reviewed :
Peer Reviewed verified by ORBi
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since 21 September 2021

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