SMOSHiLat: microwave L-band emissions of organic-rich soils in the Northern cold climate zone in support of the SMOS Mission

• Main Authors: Bircher, Simone, Richaume, Philippe, Demontoux, François, Mahmoodi, Ali, Jonard, François, Weihermüller, Lutz, Andreasen, Mie, Ikonen, Jaakko, Vehviläinen, Juho, Razafindratsima, Stephen, Rautiainen, Kimmo, Schwank, Mike, Mialon, Arnaud, Wigneron, Jean-Pierre, Kerr, Yann H.
• Other Authors: Centre d'études spatiales de la biosphère (CESBIO), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales Toulouse (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1, Forschungszentrum Jülich GmbH, Helmholtz-Gemeinschaft = Helmholtz Association, Department of Geosciences and Natural Resource Management Copenhagen (IGN), Faculty of Science Copenhagen, University of Copenhagen = Københavns Universitet (KU)-University of Copenhagen = Københavns Universitet (KU), Finnish Meteorological Institute (FMI), Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Interactions Sol Plante Atmosphère (UMR ISPA), Institut National de la Recherche Agronomique (INRA)-Ecole Nationale Supérieure des Sciences Agronomiques de Bordeaux-Aquitaine (Bordeaux Sciences Agro), European Space Agency (ESA). INT.
• Format: Conference Object
• Language: English
• Published: HAL CCSD 2015
• Subjects: [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; [SPI.SIGNAL]Engineering Sciences [physics]/Signal and Image processing; [SPI.ELEC]Engineering Sciences [physics]/Electromagnetism; [SDE.MCG]Environmental Sciences/Global Changes; [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces; environment; Islay; Sodankylä
• Online Access: https://hal.inrae.fr/hal-02742610

International audience L-band microwave (1.4 GHz) brightness temperature (TB) observations of the Soil Moisture and Ocean Salinity (SMOS) satellite are used to retrieve global soil moisture data, taking advantage of the large difference between the dielectric constant of dry soil and water. The retrieval is based on the L-band Microwave Emission of the Biosphere (L-MEB) model using tuning parameters derived from study sites in dry and temperate climate zones. Thus, the aim of the SMOSHiLat project (ESA’s STSE Changing Earth Science Network) is to improve our understanding of L-band emissions and supporting SMOS data quality in more northern climate zones covered by pronounced organic surface layers. A database is created including L-band TB and dielectric constant measurements of organic-rich soils, mainly from (1) Sodankylä, Finland (Finish Meteorological Institute), and (2) Gludsted, Denmark (HOBE). Additional organic samples are available from Islay, Scotland, and the West Siberian Plain, Russia. The L-band dielectric constant measurements conducted at the IMS Laboratory (Bordeaux, France), show no distinct variability between a range of humus types encountered in the four regions. Due to the increased bound water fraction in porous organic material dielectric constants are consistently lower than measured in the underlying sandy mineral soils. Hence, one function was fitted through all organic soil moisture – dielectric constant couples, and tested in L-MEB by means of the tower-based ELBARA radiometer dataset acquired at the Research Center Jülich using Danish organic-rich soil. The derived relation proved satisfactory, and consequently, was implemented in the SMOS Soil Moisture Level 2 Prototype Processor (SML2PP). First runs were conducted over the Sodankylä test site and compared with retrieved soil moisture using the Dobson and Mironov dielectric mixing models. Results demonstrated significantly wetter retrieved soil moisture when using the organic fit function. This is in better agreement with an in ...