The SMOS Soil Moisture Retrieval Algorithm
Yann Kerr,Philippe Waldteufel,P. Richaume,Jean-Pierre Wigneron,Paolo Ferrazzoli,A. Mahmoodi,Ahmad Al Bitar,Francois Cabot,C. Gruhier,S. Juglea,Delphine Leroux,Arnaud Mialon,Steven Delwart +12 more
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TLDR
A retrieval algorithm to deliver global soil moisture (SM) maps with a desired accuracy of 0.04 m3/m3 is given, discusses the caveats, and provides a glimpse of the Cal Val exercises.Abstract:
The Soil Moisture and Ocean Salinity (SMOS) mission is European Space Agency (ESA's) second Earth Explorer Opportunity mission, launched in November 2009. It is a joint program between ESA Centre National d'Etudes Spatiales (CNES) and Centro para el Desarrollo Tecnologico Industrial. SMOS carries a single payload, an L-Band 2-D interferometric radiometer in the 1400-1427 MHz protected band. This wavelength penetrates well through the atmosphere, and hence the instrument probes the earth surface emissivity. Surface emissivity can then be related to the moisture content in the first few centimeters of soil, and, after some surface roughness and temperature corrections, to the sea surface salinity over ocean. The goal of the level 2 algorithm is thus to deliver global soil moisture (SM) maps with a desired accuracy of 0.04 m3/m3. To reach this goal, a retrieval algorithm was developed and implemented in the ground segment which processes level 1 to level 2 data. Level 1 consists mainly of angular brightness temperatures (TB), while level 2 consists of geophysical products in swath mode, i.e., as acquired by the sensor during a half orbit from pole to pole. In this context, a group of institutes prepared the SMOS algorithm theoretical basis documents to be used to produce the operational algorithm. The principle of the SM retrieval algorithm is based on an iterative approach which aims at minimizing a cost function. The main component of the cost function is given by the sum of the squared weighted differences between measured and modeled TB data, for a variety of incidence angles. The algorithm finds the best set of the parameters, e.g., SM and vegetation characteristics, which drive the direct TB model and minimizes the cost function. The end user Level 2 SM product contains SM, vegetation opacity, and estimated dielectric constant of any surface, TB computed at 42.5°, flags and quality indices, and other parameters of interest. This paper gives an overview of the algorithm, discusses the caveats, and provides a glimpse of the Cal Val exercises.read more
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Journal ArticleDOI
Comparison of Dobson and Mironov Dielectric Models in the SMOS Soil Moisture Retrieval Algorithm
Arnaud Mialon,Philippe Richaume,Delphine Leroux,Simone Bircher,Ahmad Al Bitar,Thierry Pellarin,Jean-Pierre Wigneron,Yann Kerr +7 more
TL;DR: Both Dobson and Mironov models were modified to ensure that the SMOS retrieval algorithm converges to realistic soil moisture retrievals and in situ measurements over various test sites do not demonstrate a superior performance of one model over the other.
Journal ArticleDOI
SMOS retrieval over forests: Exploitation of optical depth and tests of soil moisture estimates
Cristina Vittucci,Paolo Ferrazzoli,Yann Kerr,Philippe Richaume,Leila Guerriero,R. Rahmoune,G. Vaglio Laurin +6 more
TL;DR: In this article, the correlation between the new vegetation optical depth (VOD) product and the height of the forest estimated by ICES at GLAS lidar on a global scale is investigated.
Journal ArticleDOI
Catchment scale validation of SMOS and ASCAT soil moisture products using hydrological modeling and temporal stability analysis
Kathrina Rötzer,Carsten Montzka,Heye Bogena,Wolfgang Wagner,Yann Kerr,R. Kidd,Harry Vereecken +6 more
TL;DR: In this article, the authors presented the validation results of the soil moisture products of the years 2010-2012 retrieved from the Soil Moisture and Ocean Salinity (SMOS) and the Advanced Scatterometer (ASCAT) for the Rur and Erft catchments in western Germany.
Journal ArticleDOI
CCI soil moisture assessment with SMOS soil moisture and in situ data under different environmental conditions and spatial scales in Spain
TL;DR: In this article, the authors evaluated active, passive and combined CCI Soil Moisture (SM) products in comparison with in situ SM measurements from five networks in Spain that have different spatial and temporal scales, densities and environmental conditions.
Journal ArticleDOI
Coupling a water balance model with forest inventory data to predict drought stress : the role of forest structural changes vs. climate changes
Miquel De Cáceres,Jordi Martínez-Vilalta,Lluís Coll,Pilar Llorens,Pere Casals,Rafael Poyatos,Juli G. Pausas,Lluís Brotons +7 more
TL;DR: In this article, a water balance model was used to predict soil moisture dynamics and plant drought stress in individual forest stands in order to predict the current and future levels of plant drought.
References
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Microwave Remote Sensing, Active and Passive
TL;DR: In this article, the authors present a model of a MICROWAVE REMOTE SENSING FUNDAMENTALS and RADIOMETRY, which is based on the idea of surface scattering.
Journal ArticleDOI
The Soil Moisture Active Passive (SMAP) Mission
Dara Entekhabi,Eni G. Njoku,Peggy O'Neill,Kent Kellogg,Wade T. Crow,W. Edelstein,Jared Entin,Shawn D Goodman,Thomas J. Jackson,Joel T. Johnson,John S. Kimball,Jeffrey R. Piepmeier,Randal D. Koster,Neil R.W. Martin,Kyle C. McDonald,Mahta Moghaddam,Susan Moran,Rolf H. Reichle,Jiancheng Shi,Michael W. Spencer,Samuel W Thurman,Leung Tsang,Jakob van Zyl +22 more
TL;DR: The Soil Moisture Active Passive mission is one of the first Earth observation satellites being developed by NASA in response to the National Research Council's Decadal Survey to make global measurements of the soil moisture present at the Earth's land surface.
Journal ArticleDOI
Microwave Dielectric Behavior of Wet Soil-Part II: Dielectric Mixing Models
TL;DR: In this paper, the authors evaluated the microwave dielectric behavior of soil-water mixtures as a function of water content and soil textural composition for the 1.4-to 18-GHz region.
Journal ArticleDOI
The SMOS Mission: New Tool for Monitoring Key Elements ofthe Global Water Cycle
Yann Kerr,Philippe Waldteufel,Jean-Pierre Wigneron,Steven Delwart,Francois Cabot,Jacqueline Boutin,Maria-José Escorihuela,Jordi Font,Nicolas Reul,C. Gruhier,S. Juglea,Mark R. Drinkwater,Achim Hahne,Manuel Martin-Neira,Susanne Mecklenburg +14 more
TL;DR: The SMOS satellite was launched successfully on November 2, 2009, and will achieve an unprecedented maximum spatial resolution of 50 km at L-band over land (43 km on average over the field of view), providing multiangular dual polarized (or fully polarized) brightness temperatures over the globe.
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