The global SMOS Level 3 daily soil moisture and brightness temperature maps

Type Article
Date 2017-06
Language English
Author(s) Al Bitar Ahmad1, 2, Mialon Arnaud1, 2, Kerr Yann H.1, 3, Cabot Francois1, 3, Richaume Philippe1, Jacquette Elsa3, Quesney Arnaud4, Mahmoodi Ali1, Tarot Stephane5, Parrens Marie1, Al-Yaari Amen6, Pellarin Thierry7, Rodriguez-Fernandez Nemesio1, Wigneron Jean-Pierre6
Affiliation(s) 1 : Univ Toulouse, UPS, Ctr Etud Spatiales Biosphere, CNES,CNRS,IRD, Toulouse, France.
2 : CNRS, Paris, France.
3 : Ctr Natl Etud Spatiales, Paris, France.
4 : CapGemini Sud, 109 Ave Gen Eisenhower, F-31000 Toulouse, France.
5 : IFREMER, BP 70, F-29280 Plouzane, France.
6 : INRA, ISPA UMR1391, Villenave Dornon, France.
7 : Univ Grenoble Alpes, IGE, CNRS, G INP,IRD, Grenoble, France.
Source Earth System Science Data (1866-3508) (Copernicus Gesellschaft Mbh), 2017-06 , Vol. 9 , N. 1 , P. 293-315
DOI 10.5194/essd-9-293-2017
WOS© Times Cited 19
Abstract

The objective of this paper is to present the multi-orbit (MO) surface soil moisture (SM) and angle-binned brightness temperature (TB) products for the SMOS (Soil Moisture and Ocean Salinity) mission based on a new multi-orbit algorithm. The Level 3 algorithm at CATDS (Centre Aval de Traitement des Donnees SMOS) makes use of MO retrieval to enhance the robustness and quality of SM retrievals. The motivation of the approach is to make use of the longer temporal autocorrelation length of the vegetation optical depth (VOD) compared to the corresponding SM autocorrelation in order to enhance the retrievals when an acquisition occurs at the border of the swath. The retrieval algorithm is implemented in a unique operational processor delivering multiple parameters (e.g. SM and VOD) using multi-angular dual-polarisation TB from MO. A subsidiary angle-binned TB product is provided. In this study the Level 3 TB V310 product is showcased and compared to SMAP (Soil Moisture Active Passive) TB. The Level 3 SM V300 product is compared to the single-orbit (SO) retrievals from the Level 2 SM processor from ESA with aligned configuration. The advantages and drawbacks of the Level 3 SM product (L3SM) are discussed. The comparison is done on a global scale between the two datasets and on the local scale with respect to in situ data from AMMA-CATCH and USDA ARS Watershed networks. The results obtained from the global analysis show that the MO implementation enhances the number of retrievals: up to 9% over certain areas. The comparison with the in situ data shows that the increase in the number of retrievals does not come with a decrease in quality, but rather at the expense of an increased time lag in product availability from 6 h to 3.5 days, which can be a limiting factor for applications like flood forecast but reasonable for drought monitoring and climate change studies. The SMOS L3 soil moisture and L3 brightness temperature products are delivered using an open licence and free of charge using a web application(https://www.catds.fr/sipad/).TheRE04 products, versions 300 and 310, used in this paper are also available at ftp://ext-catds-cpdc:catds2010@ftp.ifremer.fr/Land_products/GRIDDED/L3SM/RE04/.

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Al Bitar Ahmad, Mialon Arnaud, Kerr Yann H., Cabot Francois, Richaume Philippe, Jacquette Elsa, Quesney Arnaud, Mahmoodi Ali, Tarot Stephane, Parrens Marie, Al-Yaari Amen, Pellarin Thierry, Rodriguez-Fernandez Nemesio, Wigneron Jean-Pierre (2017). The global SMOS Level 3 daily soil moisture and brightness temperature maps. Earth System Science Data, 9(1), 293-315. Publisher's official version : https://doi.org/10.5194/essd-9-293-2017 , Open Access version : https://archimer.ifremer.fr/doc/00388/49941/