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
Reads0
Chats0
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
Citations
More filters
Journal ArticleDOI
Impact of temporal variations in vegetation optical depth and vegetation temperature on L-band passive soil moisture retrievals over a tropical forest using in-situ information
Alejandro Monsivais-Huertero,Juan Carlos Hernandez-Sanchez,Jose Carlos Jimenez-Escalona,Jose Mauricio Galeana-Pizana,Daniel Enrique Constantino-Recillas,Aura Citlalli Torres-Gomez,Ramata Magagi,Kalifa Goïta,Stéphane Couturier +8 more
TL;DR: In this paper, the Soil Moisture and Ocean Salinity (SMOS) and Soil Mixture Active Passive (SMAP) missions provide estimates of soil moisture at similar spatial resolutions using L-band brightness temperatu...
Journal ArticleDOI
Review of the CALIMAS Team Contributions to European Space Agency’s Soil Moisture and Ocean Salinity Mission Calibration and Validation
Adriano Camps,J. Font,Ignasi Corbella,M. Vall-llossera,Marcos Portabella,Joaquim Ballabrera-Poy,Verónica González,Maria Piles,Albert Aguasca,R. Acevo,Xavier Bosch,Nuria Duffo,Pedro Fernández,Carolina Gabarró,Jérôme Gourrion,Sébastien Guimbard,Anna Marín,Justino Martínez,Alessandra Monerris,Baptiste Mourre,Fernando Alonso Pérez,Nereida Rodríguez,Joaquín Salvador,Roberto Sabia,Marco Talone,Francesc Torres,Miriam Pablos,A. Turiel,Enric Valencia,José Martínez-Fernández,Nilda Sánchez,C. Perez-Gutierrez,Guido Baroncini-Turricchia,Antonio Rius,Serni Ribó +34 more
TL;DR: Results from CALIMAS show a satisfactory performance of the MIRAS instrument, the accuracy and efficiency of the algorithms implemented in the ground data processors, and explore the limits of spatial resolution of soil moisture products using data fusion, as well as the feasibility of GNSS-R techniques for sea state determination and soil moisture monitoring.
Journal ArticleDOI
Global Sensitivity Analysis of the L-MEB Model for Retrieving Soil Moisture
TL;DR: The analysis indicates that calibration experiments performed at small incidence angles may be appropriate for some but not all of the model parameters, which characterize the effect of soil surface roughness and vegetation on the terrestrial brightness temperature.
Journal ArticleDOI
An approach to validate soil moisture derived from passive microwave sensors using SAR as an interface
TL;DR: In this article, the authors used nine spatial/temporal synthetic aperture radar SAR data sets from Radar Satellite-1 Radarsat-1 and Environmental Satellite 1 Envisat 1 Advanced Synthetic Aperture Radar ASAR as an interface to upscale the field-level soil moisture to soil moisture at a 25-km-×-25-km grid, leading to a total of 68 such grids where there is a pair of SAR-derived and corresponding AMSR-E derived values.
Journal ArticleDOI
Impact of regional characteristics on the estimation of root-zone soil moisture from the evaporative index or evaporative fraction
TL;DR: In this paper, the authors evaluate the impact of regional soil, vegetation, and climatic conditions on the form and strength of the Λ S E B − θ ¯, Λ P E T − , B − s¯, and T − s ¯ relationships.
References
More filters
Book
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.
Related Papers (5)
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