Issues in the balancing of the SMOS ocean salinity trieval cost function

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SMOS: ESA'S Water Mission

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SMOS Measurements Preliminary Validation: Objectives and Approach

European Geosciences Union General Assembly, 2-7 May 2010, Vienna, Austria.-- 2 pagesThe Earth Explorer Soil Moisture and Ocean Salinity (SMOS) mission was successfully launched on November 2nd, 2009, in the framework of the European Space Agency Living Planet programme. It will provide long-awaited remotely-sensed Sea Surface Salinity (SSS) maps over the oceans with a 3-day revisiting time [1]. The SMOS Barcelona Expert Centre (SMOS-BEC) in Barcelona, Spain, will be involved in several activities at different levels of the salinity retrieval processing chain, which are classified according to the objectives/issues being addressed. In particular, those described hereafter refer to the validation of the products and the consolidation/improvement of the salinity retrieval procedure itself [2]. This will be carried out by performing specific comparisons against modelled brightness temperatures (TB) or external salinity data sources. Due to start at the beginning of the Commissioning Phase, the post-launch 6-month checkout and calibration period, these studies will continue through the nominal satellite operation phase. They will support the choice of an optimal data selection strategy in regard to the existing trade-off, for instance the Ascending/Descending tracks selection, the AF-FOV/EAF-FOV (Alias-Free Field Of View/Extended Alias-Free Field Of View) selection, and some possible across-track data filtering. Moreover, they will help in the definition of an optimal processing configuration (separated polarization retrieval versus first Stokes parameter retrieval). Concerning the TB, the approach is to perform inter-comparisons of the TB departures (SMOS TB minus modelled TB, assuming knowledge of auxiliary information and proper TB direct modelling). [...]Peer reviewe

Correcting the FRA systematic error in VTEC maps from SMOS radiometric data

The Faraday rotation (FR) is a nonnegligible effect at the L-band, which is the operation frequency of the Soil Moisture and Ocean Salinity (SMOS) mission. This effect introduces a rotation in the electromagnetic field polarization when propagating through the ionosphere that must be compensated. Recently, a methodology was developed in order to retrieve the vertical total electron content (VTEC) from SMOS radiometric data with the aim to better correct the FR effect [1] . In that work, systematic patterns in the retrieved FR angle (FRA) were detected. In this article, these systematic patterns are characterized and corrected to improve the quality of the retrieved VTEC maps. These maps can be then reused in the SMOS level 2 processor for the correction of the FRA in the mission. The impact of using the SMOS-derived VTEC maps instead of the VTEC data from global positioning system (GPS) measurements on the ocean brightness temperatures (TB) measurement has also been analyzed. Results of this analysis show that the usage of those maps allows a significant enhancement in the quality of the TB, which will lead to an improvement on salinity retrievals.This work was supported in part by the European Space Agency, Soil Moisture and Ocean Salinity (SMOS) Expert Support Laboratories (ESL) for SMOS Level 1 and Level 2 over Land, Ocean and Ice Project under Grant RFQ/3-16138/19/I-BG; in part by the SMOS P7 under Contract DME CP12 no. 2015-005 (in joint with Deimos Engenharia, Portugal); in part by the Spanish Public Funds under Project TEC2017-88850-R and Project ESP2015-67549-C3-1-R through the Award “Unidad de Excelencia María de Maeztu” MDM-2016-0600, financed by the “Agencia Estatal de Investigación” (Spain); in part by the European Regional Development (ERDF); in part by the SMOS ESL for SMOS Level 1 and Level 2 over Land, Ocean and Ice Project under Grant ARG/003-032/0315/ICMCSIC; in part by the Spanish Research and Development Project INTERACT under Grant PID2020-114623RB-C31; and in part by the Spanish Government through the “Severo Ochoa Centre of Excellence” accreditation under Grant CEX2019-000928-S.Peer ReviewedPostprint (author's final draft

Faraday Rotation Correction for Passive Microwave Remote Sensing from Space

Faraday rotation (FR) is one of the main error sources for passive microwave remote sensing from space especially in frequencies less than or equal to 10.7 GHz. In this paper, Faraday rotation correction for the vertical brightness temperature at L band and the third Stokes parameter brightness temperature at 10.7 GHz are discussed. Two approaches are studied to remove the influence of FR: correction by auxiliary data and correction by polarimetric mode. At 1.4 GHz, correction by polarimetric mode performs better than correction by auxiliary data. At 10.7 GHz, correction by auxiliary data is feasible while polarimetric mode correction becomes invalid. We propose a new method of using TEC data released by international GNSS service (IGS) for correction. It has been proved that the residual correction errors are reduced. IGS data method greatly improves the correction accuracy

2000 days of SMOS at the Barcelona Expert Centre: a tribute to the work of Jordi Font

Soil Moisture and Ocean Salinity (SMOS) is the first satellite mission capable of measuring sea surface salinity and soil moisture from space. Its novel instrument (the L-band radiometer MIRAS) has required the development of new algorithms to process SMOS data, a challenging task due to many processing issues and the difficulties inherent in a new technology. In the wake of SMOS, a new community of users has grown, requesting new products and applications, and extending the interest in this novel brand of satellite services. This paper reviews the role played by the Barcelona Expert Centre under the direction of Jordi Font, SMOS co-principal investigator. The main scientific activities and achievements and the future directions are discussed, highlighting the importance of the oceanographic applications of the mission.Peer ReviewedPostprint (published version

Obtenció i integració del model SMOS de l'oceà creat pel Barcelona Expert Center (BEC)

Obtaining global terrestrial data in real time has become one of the most powerful scientific challenges of today and using satellites and nano satellites we can receive the necessary information to solve this task. In 2009 ESA (European Space Agency) launched the SMOS (Soil Moisture and Ocean Salinity) satellite with the objective of capturing global data using innovative techniques in order to obtain soil moisture and ocean salinity maps every 3 days. The access to this information allowed the development of new scientific studies in order to understand the functioning of the different water cycles in our planet and try to understand what alterations it has suffered over the years due to human activity. The TSC (Signal and Communications Theory) department of the UPC (Universitat Politècnica de Catalunya) participates in the processing of the data obtained by SMOS since its launch. The project developed in the following document aims to obtain a new model of the ocean developed by the BEC (Barcelona Expert Center), a research center that also participates in different SMOS data processing tasks. In order to carry out this task, we have had to work together to adapt the procedures to obtain the model so that it is useful in the TSC working environment. After several months of work, the procedure was correctly established and today we have been able to obtain the first years of modeled ocean. Obtaining the new model opens the door to new studies to evaluate the state of the satellite and the quality of the data obtained by it, since it is more than 10 years of its launching and all hardware has a limited useful life. By means of models, it is possible to obtain a very useful type of graphs, the Hovmoller graphs. This allow to obtain the difference between the results obtained from the model and the measurements taken by the SMOS and to be plotted. Once the processing to obtain the BEC model has been completed, Hovmollers obtained from it might bring to relevant conclusions.La obtención de datos globales Terrestres a tiempo real se ha convertido en uno de los retos científicos más poderosos de hoy en día y mediante el uso de satélites y nano satélites podemos recibir la información necesaria para resolver dicha tarea. En el año 2009 la ESA (Agencia Espacial Europea) lanzó el satélite SMOS (Soil Moisture and Ocean Salinity) con el objetivo de captar datos globales mediante técnicas innovadoras con el fin de obtener mapas de humedad del suelo y salinidad de los océanos cada 3 días. El acceso a dicha información permitió desarrollar nuevos estudios científicos con el fin de entender el funcionamiento de los diferentes ciclos que vive el agua en nuestro planeta e intentar entender qué alteraciones ha sufrido a lo largo de los años debido a la actividad humana. El departamento TSC (Teoría de Señal y Comunicaciones) de la UPC (Universitat Politècnica de Catalunya) participa en el procesado de los datos obtenidos por el SMOS desde su lanzamiento. El proyecto desarrollado en el siguiente documento tiene como objetivo la obtención de un nuevo modelo del océano desarrollado por el BEC (Barcelona Experto Center), centro de investigación que también participa en diferentes tareas de procesado de datos del SMOS. Para llevar a cabo esta tarea, hemos tenido que trabajar conjuntamente para adecuar los procedimientos de obtención del modelo para que sea útil en el entorno de trabajo del TSC. Después de diferentes meses de trabajo, se pudo establecer correctamente el procedimiento y a día de hoy se han podido obtener los primeros años de océano modelado. La obtención del nuevo modelo abre las puertas a nuevos estudios que permitan evaluar el estado del satélite y la calidad de los datos obtenidos por este, puesto que hace más de 10 años de su lanzamiento y todo hardware tiene una vida útil limitada. Mediante modelos, se pueden obtener un tipo de gráficas muy útiles a golpe visual, las gráficas Hovmoller. Estas permiten dibujar la diferencia que hay entre los resultados obtenidos del modelo y las medidas tomadas por la SMOS. Una vez se haya completado el procesado de obtención del modelo del BEC se pretende obtener Hovmollers a partir de este para que mediante su posterior análisis se pueda llegar a extraer conclusiones relevantes.L'obtenció de dades globals Terrestres a temps real s'ha convertit en un dels reptes científics més poderosos d'avui en dia i mitjançant l'ús de satèl·lits i nano satèl·lits podem rebre la informació necessària per resoldre aquesta tasca. L'any 2009 l'ESA (Agència Espacial Europea) va llençar el satèl·lit SMOS (Soil Moisture and Ocean Salinity) amb l'objectiu de captar dades globals mitjançant tècniques innovadores amb el fi d'obtenir mapes d'humitat del sòl i salinitat dels oceans cada 3 dies. L'accés a llur informació va permetre desenvolupar nous estudis científics amb el fi d'entendre el funcionament dels diferents cicles que viu l'aigua en el nostre planeta i intentar entendre quines alteracions ha patit al llarg dels anys degut a l'activitat humana. El departament TSC (Teoria de Senyal i Comunicacions) de la UPC (Universitat Politècnica de Catalunya) participa en el processat de les dades obtingudes per l'SMOS des del seu llançament. El projecte desenvolupat en el següent document té com a objectiu l'obtenció d'un nou model de l'oceà desenvolupat pel BEC (Barcelona Expert Center), centre d'investigació que també participa en diferents tasques de processat de dades de l'SMOS. Per tal de dur a terme aquesta tasca, hem hagut de treballar conjuntament per tal d'adequar els procediments d'obtenció del model per a que sigui útil en l'entorn de treball del TSC. Després de diferents mesos de feina, es va poder establir correctament llur procediment i a dia d'avui s'han pogut obtenir els primers anys d'oceà modelat. L'obtenció del nou model obra les portes a nous estudis que permetin avaluar l'estat del satèl·lit i la qualitat de les dades obtingudes per aquest, ja que fa més de 10 anys del seu llançament i tot hardware té una vida útil limitada. Mitjançant models, és poden obtenir un tipus de gràfiques molt útils a cop visual, les gràfiques Hovmoller. Aquetes permeten dibuixar la diferència que hi ha entre els resultats obtinguts del model i les mesures preses per l'SMOS. Una vegada s'hagi completat el processat d'obtenció del model del BEC es pretén obtenir Hovmollers a partir d'aquest per a que mitjançant un posterior anàlisis es pugui arribar a extreure conclusions rellevants