1. Global-Scale Evaluation of Roughness Effects on C-Band AMSR-E Observations
- Author
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Jean-Pierre Wigneron, Roberto Fernandez-Moran, Amen Al-Yaari, Xiaoyong Yu, Marie Parrens, Yann Kerr, Qin-Yu Ye, Lingmei Jiang, Shu Wang, Wei Ji, Beijing Normal University (BNU), 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), 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), Universitat de València (UV), Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences [Changchun Branch] (CAS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), and Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)
- Subjects
010504 meteorology & atmospheric sciences ,télédétection ,Science ,0211 other engineering and technologies ,Weather forecasting ,[SDU.STU]Sciences of the Universe [physics]/Earth Sciences ,Electromagnétisme ,soil surface roughness ,02 engineering and technology ,Surface finish ,computer.software_genre ,donnée satellite ,01 natural sciences ,Sciences de la Terre ,Normalized Difference Vegetation Index ,soil moisture ,AMSR-E ,Electromagnetism ,Emissivity ,Surface roughness ,Traitement du signal et de l'image ,14. Life underwater ,Water content ,021101 geological & geomatics engineering ,0105 earth and related environmental sciences ,Remote sensing ,Radiometer ,capteur smos ,Signal and Image processing ,radiométrie microondes ,Vegetation ,15. Life on land ,[SPI.ELEC]Engineering Sciences [physics]/Electromagnetism ,Earth Sciences ,General Earth and Planetary Sciences ,Environmental science ,computer ,[SPI.SIGNAL]Engineering Sciences [physics]/Signal and Image processing - Abstract
Quantifying roughness effects on ground surface emissivity is an important step in obtaining high-quality soil moisture products from large-scale passive microwave sensors. In this study, we used a semi-empirical method to evaluate roughness effects (parameterized here by the parameter) on a global scale from AMSR-E (Advanced Microwave Scanning Radiometer for EOS) observations. AMSR-E brightness temperatures at 6.9 GHz obtained from January 2009 to September 2011, together with estimations of soil moisture from the SMOS (Soil Moisture and Ocean Salinity) L3 products and of soil temperature from ECMWF’s (European Centre for Medium-range Weather Forecasting) were used as inputs in a retrieval process. In the first step, we retrieved a parameter (referred to as the parameter) accounting for the combined effects of roughness and vegetation. Then, global MODIS NDVI data were used to decouple the effects of vegetation from those of surface roughness. Finally, global maps of the Hr parameters were produced and discussed. Initial results showed that some spatial patterns in the values could be associated with the main vegetation types (higher values of were retrieved generally in forested regions, intermediate values were obtained over crops and grasslands, and lower values were obtained over shrubs and desert) and topography. For instance, over the USA, lower values of were retrieved in relatively flat regions while relatively higher values were retrieved in hilly regions.
- Published
- 2015
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