Graphic summary
  • Show / hide key
  • Information


Scientific and technological production
  •  

1 to 50 of 286 results
  • Radiation and Propagation: Test on Linear Circuits (English)

     Torres Torres, Francisco; Corbella Sanahuja, Ignasi; Fabregas Canovas, Francisco Javier; López Martínez, Carlos
    Date: 2014-01-07
    Report

     Share Reference managers Reference managers Open in new window

  • RP: Autotest conocimientos previos Circuitos Lineales

     Torres Torres, Francisco; Corbella Sanahuja, Ignasi; Fabregas Canovas, Francisco Javier; López Martínez, Carlos
    Date: 2014-01-07
    Report

     Share Reference managers Reference managers Open in new window

  • Contribution to spatial bias mitigation in interferometric radiometers devoted to Earth observation: Application to the SMOS mission  Open access

     Wu, Lin
    Department of Signal Theory and Communications, Universitat Politècnica de Catalunya
    Theses

    Read the abstract Read the abstract Access to the full text Access to the full text Open in new window  Share Reference managers Reference managers Open in new window

    Aquesta tesi s'ha portat a terme en el marc de la beca FPI BES-2009-028505 del 30/07/2009, "Secretaría de Estado de Investigación del Ministerio de Ciencia e Innovación", associada al projecte TEC2008-06764-C02-01 (Universitat Politècnica de Catalunya) titulat "Advanced concepts on active and passive microwave remote sensing: technology and applications". En un sentit més ampli, el treball s'engloba dins de les activitats del Grup de Teledetecció (RSLab) del Departament de Teoria del Senyal i Comunicacions, UPC, en el marc de la missió SMOS (Soil Moisture and Ocean Salinity) de l'Agència Europea de l'Espai (ESA). El treball es divideix en:1) Prestacions del sensor SMOSUna primera avaluació de las prestacions de SMOS es varen obtenir en finalitzar la fase de comissionat de la missió al maig de 2010. Així, com a primer pas d'aquest treball, s'han revisat els procediments per a avaluar la sensibilitat i els errors espacials de SMOS, desenvolupant noves tècniques per a millorar la comparació de les imatges mesurades a blancs coneguts (ground truth). Com a millor opció s'han triat imatges de SMOS sobre l' oceà, caracteritzades per variacions suaus de la temperatura de brillantor per a les quals existeixen models teòrics acurats.2) Tècniques de reducció dels errors espacialsUn dels principals problemes en les primeres imatges de SMOS eren els errors espacials, sensiblement més grans que els previstos. Així, de forma sistemàtica i per a identificar el seu origen, cada font potencial d'error en el calibratge de l'instrument s'ha simulat i s'ha comparat el seu impacte amb els mapes d'error mesurats per l'instrument. 3) Errors espacials en el camp de visió ampliat lliure d'àlies, (EAF-FoV)Inicialment, la degradació de les prestacions del sensor era especialment important en l'anomenat EAF-FoV. Així, per a identificar les causes d'error, el problema s'ha abordat de dos formes: primer, s'ha dividit el camp de visió en diferents àrees d'interès d'acord al nombre i posició dels àlies i s'han ordenat els punts d'acord amb l'angle d'incidència. Després s'ha avaluat el impacte del calibratge i els diferents mètodes d'inversió en cada una d'aquestes àrees.4) Errors espacials de SMOS en mode polarimètric (full-pol)L'objectiu principal d'aquesta tesi s'ha assolit en finalitzar el desenvolupament d'un procediment de mesura i reconstrucció d'imatges en mode full-pol, que ha produït mapes de temperatura polarimètrica d'una qualitat clarament superior. Aquesta eina ha permès també una anàlisi sistemàtica de les dues causes d'error espacial residuals: l'anomenat error mínim (floor error) i els motivats per la incertesa en els diagrames de radiació de les antenes. Finalment, s'han produït mapes operacionals del fenomen de rotació de Faraday com a validació de la qualitat de las mesures polarimètricas produïdes per SMOS en mode full-pol.

    This work has been undertaken within the frame of the FPI scholarship BES-2009-028505 of 30/07/2009, by the "Secretario de Estado de Investigación del Ministerio de Ciencia e Innovación", related to the project TEC2008-06764-C02-01 (Universitat Politècnica de Catalunya) titled "Advanced concepts on active and passive microwave remote sensing: technology and applications". In a more general scope, this thesis is related to the Remote Sensing Laboratory (Signal Theory & Communication Department, UPC) on-going activities, within the SMOS (Soil Moisture and Ocean Salinity) mission by the European Space Agency (ESA). These activities have been organized to provide original advances in the following four main topics: 1) SMOS system performance assessment. SMOS commissioning phase finalized in May 2010 providing preliminary performance results. Therefore, as a first step in this work, radiometric sensitivity and spatial bias (systematic spatial errors) have been reviewed and assessed. To achieve this, new techniques have been developed to better compare SMOS images to ground truth targets. SMOS ocean views have been selected as the best option since provide smooth brightness temperature distributions for which accurate models are available. 2) Spatial bias mitigation techniques. Spatial bias was a major issue in SMOS first images since it was larger than expected. In order to identify the dominant sources of spatial bias, each potential source of error, at calibration level,has been simulatedand compared tomeasured SMOS error patterns. 3) Spatial bias in the EAF-FoV. Whereas SMOS performance in the alias free FoV was well within mission requirements, this issue was especially important for the four polarimetric temperatures in the extended regions. This issuehas been addressed in two ways. First a new approach has been developed to systematically analyze spatial bias by splitting SMOS EAF-FoV into different regions of interest. Also, the pixels have been arranged per angle of incidence. Secondly, the impact in each region of calibration errors and different image reconstruction has been addressed. 4) Spatial bias in full-pol measurement.The main objective of this work has been achieved by developing, implementing and validating a SMOS full-pol G-matrix image reconstruction procedure that resulted into significantly improved polarimetric images. This tool allowed a comprehensive assessment of the two error contributions that have been identified as the main sources of residual spatial bias: the so-called floor error and antenna pattern uncertainty. Finally, as a validation of the quality of SMOS Level 1 fully polarimetric data that has been achieved, the last chapter of this work has been devoted to provide operational Faraday rotation retrievals in a per snap-shot basis.

  • Practical issues on SMOS single antenna patterns

     Wu, Lin; Duran Martinez, Israel; Torres Torres, Francisco; Corbella Sanahuja, Ignasi; Duffo Ubeda, Nuria; Closa, Josep; Manrique, Rodrigo; Garcia, Quiterio; Oliva, Roger; Martín Neira, Manuel
    Specialist Meeting on Microwave Radiometry and Remote Sensing of the Environment
    p. 197-200
    DOI: 10.1109/MicroRad.2014.6878938
    Presentation's date: 2014-03
    Presentation of work at congresses

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    This paper provides a wrap-up of some of the activities undertaken by SMOS L1 team to fine tune the instrument calibration and modeling that eventually has resulted into a SMOS full-polarimetric measurement and image reconstruction enhanced performance

    This paper provides a wrap-up of some of the activities undertaken by SMOS L1 team to fine tune the instrument calibration and modeling that eventually has resulted into a SMOS full-polarimetric measurement and image reconstruction enhanced performance

  • Towards a SMOS operational mission: SMOSOps-Hexagonal

     Zurita Campos, Alberto Manuel; Corbella Sanahuja, Ignasi; Martín Neira, Manuel; Plaza, Miguel Angel; Torres Torres, Francisco; Benito, Francisco Javier
    IEEE transactions on geoscience and remote sensing
    Vol. 6, num. 3, p. 1769-1780
    DOI: 10.1109/JSTARS.2013.2265600
    Date of publication: 2013-06-03
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    The Microwave Imaging Radiometer with Aperture Synthesis (MIRAS) on-board the Soil Moisture and Ocean Salinity (SMOS) mission is providing useful data since November 2009, and proving the potential of 2D interferometry from space. With the end of its nominal operation phase in November 2012, the mission is expected to extend its lifetime for at least more than two additional years. Along with all the current improvements on data processing and exploitation, the SMOS trail might need to be continued with the aim of providing data to the users in the coming years. This paper presents a SMOS follow-on operational mission which is the result of integrating the actual lessons learnt from MIRAS with a novel hexagonal array geometry, proving robustness against radio-frequency interferences (RFI) and receiver failures. The performance and the instrument architecture enhancements are exposed, along with a practical deployment solution.

    The Microwave Imaging Radiometer with Aperture Synthesis (MIRAS) on-board the Soil Moisture and Ocean Salinity (SMOS) mission is providing useful data since November 2009, and proving the potential of 2D interferometry from space. With the end of its nominal operation phase in November 2012, the mission is expected to extend its lifetime for at least more than two additional years. Along with all the current improvements on data processing and exploitation, the SMOS trail might need to be continued with the aim of providing data to the users in the coming years. This paper presents a SMOS follow-on operational mission which is the result of integrating the actual lessons learnt from MIRAS with a novel hexagonal array geometry, proving robustness against radio-frequency interferences (RFI) and receiver failures. The performance and the instrument architecture enhancements are exposed, along with a practical deployment solution.

  • Radiometric performance of SMOS full polarimetric imaging

     Wu, Lin; Torres Torres, Francisco; Corbella Sanahuja, Ignasi; Duffo Ubeda, Nuria; Duran Martinez, Israel; Vall-llossera Ferran, Mercedes Magdalena; Camps, Adiano; Delwart, Steven; Martín Neira, Manuel
    IEEE Geoscience and Remote Sensing Letters
    Vol. 10, num. 6, p. 1454-1458
    DOI: 10.1109/LGRS.2013.2260128
    Date of publication: 2013-11
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    This work has been conducted in the framework of several projects devoted to assess the performance of the Soil Moisture and Ocean Salinity (SMOS) mission full-pol measurement mode. Since its launch in November 2009, SMOS is producing dual-polarization brightness temperature synthesized images that are yielding a high scientific return. However, these images are affected by a non-negligible spatial amplitude error, the so-called spatial bias (SB), that degrades geophysical parameter retrieval. This effect is particularly detrimental in SMOS polarimetric images where spatial bias is masking the polarimetric physical signature to a large extend. This paper presents a method to mitigate SMOS spatial bias by taking into account the co-and cross-polar antenna patterns in the image reconstruction algorithm through the, so called, full-pol G-matrix (FPG). The method is validated by producing spatial bias maps out of the comparison between SMOS full-pol images and an accurate polarimetric brightness temperature model of the ocean. This model has been provided to SMOS ESLs (Expert Support Laboratories) by LOCEAN (Laboratoire d'Océanographie et du Climat, France) as a test bench to validate and improve SMOS Level 1 (L1) data. Finally, a radiometric performance summary table comparing spatial bias and radiometric sensitivity between this new FPG approach and SMOS current co-polar G-matrix approach (CPG) is provided. This paper presents the best quality SMOS polarimetric images, which may lead a breakthrough in the science returns of the mission.

  • Impact of the local oscillator calibration rate on the SMOS measurements and retrieved salinities

     Gabarro Prats, Carolina; Gonzalez Gambau, Verónica; Corbella Sanahuja, Ignasi; Torres Torres, Francisco
    IEEE transactions on geoscience and remote sensing
    Vol. 51, num. 9, p. 4633-4642
    DOI: 10.1109/TGRS.2012.2233744
    Date of publication: 2013-09-02
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    The local oscillators (LOs) of the Soil Moisture and Ocean Salinity mission payload are used to shift the operating frequency of the 72 receivers to an optimal intermediate frequency needed for the signal processing. The LO temperature variations produce phase errors in the visibility, which result in a blurring of the reconstructed brightness temperature (Tb) image. At the end of the commissioning phase, it was decided to calibrate the LO every 10 min while waiting for a more in-depth analysis. During short periods of time, the LOcalibration has been performed every 2 min to assess the impact of a higher calibration rate on the quality of the data. In this paper, by means of a decimation experiment, the relative errors of 6- and 10-min calibration interval data sets are estimated using the 2 min as a reference. A noticeable systematic across- and along-track pattern of amplitude ±0.3 K is observed for Tb differences between 10 and 2 min, whereas this is reduced between 6 and 2 min. A simulation experiment confirms that the nature of such systematic pattern is due to the visibility phase errors induced by the LO calibration rate. Such pattern is propagated into the sea surface salinity (SSS) retrievals. Overall, the SSS error increase (relative to the 2min SSS data) is about 0.39 and 0.14 psu for the 10- and 6-min data sets, respectively. This paper shows that a LO calibration rate of at least 6 min would noticeably improve the SSS retrievals.

  • SMOS calibration and instrument performance after one year in orbit

     Oliva Martínez, Ramon; Martín Neira, Manuel; Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Kainulainen, Juha; Tenerelli, Joseph; Cabot, François; Martín Porqueras, Fernando
    IEEE transactions on geoscience and remote sensing
    Vol. 51, num. 1, p. 654-670
    DOI: 10.1109/TGRS.2012.2198827
    Date of publication: 2013
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    This paper summarizes the rationale for the European Space Agency's Soil Moisture and Ocean Salinity (SMOS) mission routine calibration plan, including the analysis of the calibration parameter annual variability, and the performances and stability of SMOS images after one year of data. SMOS spends 1.68% of the total observation time in calibration. The instrument performs well within expectations with regard to accuracy and radiometric sensitivity, although spatial ripples are present in SMOS images. Several mechanisms are currently used or under investigation to mitigate this problem. Also, a loss antenna model has recently been introduced to correct for physical temperature-induced effects. This antenna model successfully corrects observed orbital variations, but has difficulties in correcting brightness temperature long-term drifting, as assessed using relatively well-known targets other than the external calibration region-cold space.

    This paper summarizes the rationale for the European Space Agency's Soil Moisture and Ocean Salinity (SMOS) mission routine calibration plan, including the analysis of the calibration parameter annual variability, and the performances and stability of SMOS images after one year of data. SMOS spends 1.68% of the total observation time in calibration. The instrument performs well within expectations with regard to accuracy and radiometric sensitivity, although spatial ripples are present in SMOS images. Several mechanisms are currently used or under investigation to mitigate this problem. Also, a loss antenna model has recently been introduced to correct for physical temperature-induced effects. This antenna model successfully corrects observed orbital variations, but has difficulties in correcting brightness temperature long-term drifting, as assessed using relatively well-known targets other than the external calibration region-cold space.

  • Radiació i propagació. Pràctiques de laboratori

     Corbella Sanahuja, Ignasi; Fabregas Canovas, Francisco Javier; Torres Torres, Francisco; Vall-llossera Ferran, Mercedes Magdalena
    Date: 2013-07-03
    Report

     Share Reference managers Reference managers Open in new window

  • Radiación y propagación (RP): colección de problemas

     Corbella Sanahuja, Ignasi; Fabregas Canovas, Francisco Javier; Torres Torres, Francisco; Vall-llossera Ferran, Mercedes Magdalena
    Date: 2013-09-02
    Report

     Share Reference managers Reference managers Open in new window

  • Radiation and Propagation (RP-2B). Exercises. October 2013

     Corbella Sanahuja, Ignasi; Fabregas Canovas, Francisco Javier; Torres Torres, Francisco; Vall-llossera Ferran, Mercedes Magdalena
    Date: 2013-10-07
    Report

     Share Reference managers Reference managers Open in new window

  • Radiació i propagació. Fulls de resposta laboratori

     Corbella Sanahuja, Ignasi; Fabregas Canovas, Francisco Javier; Torres Torres, Francisco; Vall-llossera Ferran, Mercedes Magdalena
    Date: 2013-07-09
    Report

     Share Reference managers Reference managers Open in new window

  • Spatial biases analysis and mitigation methods in SMOS images

     Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Wu, Lin; Duffo Ubeda, Nuria; Duran Martinez, Israel; Martín Neira, Manuel
    IEEE International Geoscience and Remote Sensing Symposium
    p. 3415-3418
    DOI: 10.1109/IGARSS.2013.6723562
    Presentation's date: 2013-07-22
    Presentation of work at congresses

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    SMOS brightness temperature images show some residual artifacts as a function of spatial directions. Due to having different antenna patterns in each element, even if knowing them perfectly, a minimum reconstruction error inherent to the inversion algorithm exists. On top of that, antenna patterns measurement errors and other effects such as cross-polarization terms, increase the spatial biases. Accurate characterization of these sources of error allows improving the quality of the SMOS images. Good results in this direction are reported.

  • In-orbit validations of SMOS full polarimetric equations

     Torres Torres, Francisco; Corbella Sanahuja, Ignasi; Wu, Lin; Duffo Ubeda, Nuria; Delwart, Steven; Martín Neira, Manuel
    IEEE International Geoscience and Remote Sensing Symposium
    p. 1930-1933
    DOI: 10.1109/IGARSS.2013.6723183
    Presentation's date: 2013-07-22
    Presentation of work at congresses

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    This paper analyzes the consistency of SMOS fully polarimetric measurement mode by comparing measured data over the ocean with the expected results. These last are based on an accurate ocean model provided by LOCEAN and simulated taking into account both the co- and cross-polar field antenna patterns. The successful image reconstruction by means of the so-called model full-pol G matrix (M-FPG) method validates SMOS main full-pol features: the full-pol switching scheme, the accuracy of the full-pol antenna pattern measurements and the full-polarimetric visibility equations.

  • A new space technology for ocean observation: the SMOS mission

     Font Ferré, Jordi; BALLABRERA POY, JOAQUIM; Camps Carmona, Adriano Jose; Corbella Sanahuja, Ignasi; Duffo Ubeda, Nuria; Duran Martínez, Israel; Emelianov Kolomitski, Mikhail; Enrique González, Luis; Fernández Gallego, Pedro; Gabarro Prats, Carolina; González, Cristina; Gonzalez Gambau, Verónica; Gourrion, J.; Guimbard, Sébastien Arnaud; Hoareau, N.; Julià, A; Kalaroni, S.; Konstantinidou, Anna; Aretxabaleta, L.; Martínez, Justino; Miranda, Jorge Miguel; Monerris Belda, Alessandra; Montero, Sergio; Mourre, B.; Pablos Hernandez, Miriam; Pérez Villar, Fernando; Piles Guillem, Maria; Portabella, Marcos; Sabia, Roberto; Salvador, Joaquin; Talone, Marco; Torres Torres, Francisco; Turiel Martínez, Antonio; Vall-llossera Ferran, Mercedes Magdalena; Villarino, Ramon
    Scientia marina
    Vol. 76, num. Supl. 1, p. 249-259
    DOI: 10.3989/scimar.03621.19K
    Date of publication: 2012
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    Capability for sea surface salinity observation was an important gap in ocean remote sensing in the last few decades of the 20th century. New technological developments during the 1990s at the European Space Agency led to the proposal of SMOS (Soil Moisture and Ocean Salinity), an Earth explorer opportunity mission based on the use of a microwave interferometric radiometer, MIRAS (Microwave Imaging Radiometer with Aperture Synthesis). SMOS, the first satellite ever addressing the observation of ocean salinity from space, was successfully launched in November 2009. The determination of salinity from the MIRAS radiometric measurements at 1.4 GHz is a complex procedure that requires high performance from the instrument and accurate modelling of several physical processes that impact on the microwave emission of the ocean’s surface. This paper introduces SMOS in the ocean remote sensing context, and summarizes the MIRAS principles of operation and the SMOS salinity retrieval approach. It describes the Spanish SMOS high-level data processing centre (CP34) and the SMOS Barcelona Expert Centre on Radiometric Calibration and Ocean Salinity (SMOS-BEC), and presents a preliminary validation of global sea surface salinity maps operationally produced by CP34.

  • Minimization of Image Distortion in SMOS Brightness Temperature Maps Over the Ocean

     Torres Torres, Francisco; Corbella Sanahuja, Ignasi; Wu, Lin; Duffo Ubeda, Nuria; Gourrion, J.; Font Ferré, Jordi; Martín Neira, Manuel
    IEEE Geoscience and Remote Sensing Letters
    Vol. 9, num. 1, p. 18-22
    DOI: 10.1109/LGRS.2011.2158799
    Date of publication: 2012-01
    Journal article

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Review of the CALIMAS Team Contributions to European Space Agency¿s Soil Moisture and Ocean Salinity Mission Calibration and Validation

     Camps Carmona, Adriano Jose; Font Ferré, Jordi; Corbella Sanahuja, Ignasi; Vall-llossera Ferran, Mercedes Magdalena; Portabella, Marcos; BALLABRERA POY, JOAQUIM; Gonzalez Gambau, Verónica; Piles Guillem, Maria; Aguasca Sole, Alberto; Acevo Herrera, René; Gabarro Prats, Carolina; Duffo Ubeda, Nuria; Bosch, Xavier; Fernández Gallego, Pedro; Gourrion, J.; Guimbard, Sébastien Arnaud; Marín, Anna; Martínez, Justino; Monerris Belda, Alessandra; Pérez, Baptiste; Pérez Villar, Fernando; Salvador, Joaquin; Sabia, Roberto; Talone, Marco; Torres Torres, Francisco; Pablos, Miriam; Martínez-Fernández, José; ANTONIO, TURIEL MARTÍNEZ; Valencia Domenech, Enric; Rodríguez Álvarez, Nereida; Sanchez, Nilda; Pérez Gutiérrez, Carlos; Baroncini Turricchia, Guido; Rius, Antonio; Ribó Vedrilla, Serni
    Remote sensing of environment
    Vol. 4, num. 5, p. 1272-1309
    DOI: 10.3390/rs4051272
    Date of publication: 2012
    Journal article

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Reduction of Secondary Lobes in Aperture Synthesis Radiometry

     Corbella Sanahuja, Ignasi; Martín Neira, Manuel; Oliva, R.; Torres Torres, Francisco; Duffo Ubeda, Nuria
    IEEE Geoscience and Remote Sensing Letters
    Vol. 9, num. 5, p. 977-979
    DOI: 10.1109/LGRS.2012.2188374
    Date of publication: 2012-09
    Journal article

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Stability of the MIRAS amplitude calibration

     Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Duffo Ubeda, Nuria; Martín Neira, Manuel
    Specialist Meeting on Microwave Radiometry and Remote Sensing of the Environment
    p. 1-3
    DOI: 10.1109/MicroRad.2012.6185235
    Presentation's date: 2012
    Presentation of work at congresses

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    Efficient methods to characterize and mitigate longand short- term drifts in SMOS data have been developed after careful analysis of the external and internal calibration parameters and by accurate modeling of the individual receiver frontends. A method to characterize this drift has been successfully developed and used to reduce the measured antenna temperature variations.

    Efficient methods to characterize and mitigate long-and short- term drifts in SMOS data have been developed after careful analysis of the external and internal calibration parameters and by accurate modeling of the individual receiver front-ends. A method to characterize this drift has been successfully developed and used to reduce the measured antenna temperature variations.

  • Spatial decorrelation of radiometric noise in SMOS measurements

     Torres Torres, Francisco; Wu, Lin; Duffo Ubeda, Nuria; Corbella Sanahuja, Ignasi; Martín Neira, Manuel
    IEEE International Geoscience and Remote Sensing Symposium
    p. 2972-2974
    DOI: 10.1109/IGARSS.2012.6350802
    Presentation's date: 2012-07-22
    Presentation of work at congresses

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Supermiras instrument development, technology and calibration

     Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Duffo Ubeda, Nuria; Martín Neira, Manuel
    IEEE International Geoscience and Remote Sensing Symposium
    p. 3427-3430
    DOI: 10.1109/IGARSS.2012.6350684
    Presentation's date: 2012-07-22
    Presentation of work at congresses

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Enhanced SMOS amplitude calibration using external target

     Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Duffo Ubeda, Nuria; Duran, Israel; Pablos, Miriam; Martín Neira, Manuel
    IEEE International Geoscience and Remote Sensing Symposium
    p. 2868-2871
    DOI: 10.1109/IGARSS.2012.6350728
    Presentation's date: 2012-07-22
    Presentation of work at congresses

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • SMOS instrument performance and calibration

     Martín Neira, Manuel; Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Kainulainen, Juha; Oliva, R.; Cabot, François; Tenerelli, Joseph
    IEEE International Geoscience and Remote Sensing Symposium
    p. 2864-2867
    DOI: 10.1109/IGARSS.2012.6350834
    Presentation's date: 2012-07-22
    Presentation of work at congresses

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Performance of a spatial error correction technique in SMOS brightness temperature images

     Wu, Lin; Torres Torres, Francisco; Corbella Sanahuja, Ignasi; Duffo Ubeda, Nuria; Martín Neira, Manuel
    Specialist Meeting on Microwave Radiometry and Remote Sensing of the Environment
    p. 1-5
    DOI: 10.1109/MicroRad.2012.6185262
    Presentation's date: 2012-03-05
    Presentation of work at congresses

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    Soil Moisture and Ocean Salinity (SMOS) brightness temperature synthesized images are obtained after a comprehensive calibration and error correction procedure. However, the final images are still contaminated by small but non-negligible spatial errors: the so-called pixel bias. These errors have been found to be very stable in the SMOS Alias-Free Field of View (AF-FoV) and can be mitigated, to a large extent, by applying a multiplicative mask to the measured brightness temperatures at the antenna plane. This paper describes the procedure to upgrade this mask to cover SMOS Extended AF­ FoV.

  • Downscaling SMOS-derived soil moisture using MODIS visible/infrared data

     Piles Guillem, Maria; Camps Carmona, Adriano Jose; Vall-llossera Ferran, Mercedes Magdalena; Corbella Sanahuja, Ignasi; Panciera, Rocco; Rudiger, Christoph; Kerr, Yann H.; Walker, Jeffrey
    IEEE transactions on geoscience and remote sensing
    Vol. 49, num. 9, p. 3156-3166
    DOI: 10.1109/TGRS.2011.2120615
    Date of publication: 2011-09
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    A downscaling approach to improve the spatial resolution of Soil Moisture and Ocean Salinity (SMOS) soil moisture estimates with the use of higher resolution visible/infrared (VIS/IR) satellite data is presented. The algorithm is based on the so-called “universal triangle” concept that relates VIS/IR parameters, such as the Normalized Difference Vegetation Index (NDVI), and Land Surface Temperature (Ts), to the soil moisture status. It combines the accuracy of SMOS observations with the high spatial resolution of VIS/IR satellite data into accurate soil moisture estimates at high spatial resolution. In preparation for the SMOS launch, the algorithm was tested using observations of the UPC Airborne RadIomEter at L-band (ARIEL) over the Soil Moisture Measurement Network of the University of Salamanca (REMEDHUS) in Zamora (Spain), and LANDSAT imagery. Results showed fairly good agreement with ground-based soil moisture measurements and illustrated the strength of the link between VIS/IR satellite data and soil moisture status. Following the SMOS launch, a downscaling strategy for the estimation of soil moisture at high resolution from SMOS using MODIS VIS/IR data has been developed. The method has been applied to some of the first SMOS images acquired during the commissioning phase and is validated against in situ soil moisture data from the OZnet soil moisture monitoring network, in South-Eastern Australia. Results show that the soil moisture variability is effectively captured at 10 and 1 km spatial scales without a significant degradation of the root mean square error.

  • MIRAS calibration and performance: results from the SMOS in-orbit commissioning phase

     Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Duffo Ubeda, Nuria; González Gambau, Veronica; Pablos Hernandez, Miriam; Duran Martínez, Israel; Martín Neira, Manuel
    IEEE transactions on geoscience and remote sensing
    Vol. 49, num. 9, p. 3147-3155
    DOI: 10.1109/TGRS.2010.2102769
    Date of publication: 2011-09
    Journal article

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    After the successful launching of the Soil Moisture and Ocean Salinity satellite in November 2009, continuous streams of data started to be regularly downloaded and made available to be processed. The first six months of operation were fully dedicated to the In-Orbit Commissioning Phase, with an intense activity aimed at bringing the satellite and instrument into a fully operational condition. Concerning the payload Microwave Imaging Radiometer with Aperture Synthesis, it was fully characterized using specific orbits dedicated to check all instrument modes. The procedures, already defined during the on-ground characterization, were repeated so as to obtain realistic temperature characterization and updated internal calibration parameters. External calibration maneuvers were tested for the first time and provided absolute instrument calibration, as well as corrections to internal calibration data. Overall, performance parameters, such as stability, radiometric sensitivity and radiometric accuracy were evaluated. The main results of this activity are presented in this paper, showing that the instrument delivers stable and well-calibrated data thanks to the combination of external and internal calibration and to an accurate thermal characterization. Finally, the quality of the visibility calibration is demonstrated by producing brightness temperature images in the alias-free field of view using standard inversion techniques. Images of ocean, ice, and land are given as examples.

  • SMOS brightness temperature measurements and end-to-end calibration

     Torres Torres, Francisco; Corbella Sanahuja, Ignasi; Duffo Ubeda, Nuria; Martín Neira, Manuel
    IEEE International Geoscience and Remote Sensing Symposium
    p. 3495-3498
    DOI: 10.1109/IGARSS.2011.6049974
    Presentation's date: 2011-07
    Presentation of work at congresses

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    SMOS is the acronym for the Soil Moisture and Ocean Salinity mission by the European Space Agency (ESA) [1]. Its single payload, the Microwave Imaging Radiometer using Aperture Synthesis (MIRAS), was launched in November 2009. After a six months Commissioning Phase SMOS entered in operational mode in May 2010. Since then SMOS has been delivering a large amount of data to successfully produce the first relevant scientific results. In order to provide accurate measurements, MIRAS requires a complex multi-step calibration procedure that was successfully tested both during pre-flight ground tests and Commissioning Phase activities. Additionally, an assessment of SMOS system performance in terms of short and long term stability, radiometric sensitivity and radiometric accuracy was also produced. In this context, this work is devoted to provide a high level overview of MIRAS calibration scheme by focusing on the rationale behind it.

  • Downscaling SMOS-derived soil moisture using MODIS visible/infrared data

     Piles Guillem, Maria; Camps Carmona, Adriano Jose; Vall-llossera Ferran, Mercedes Magdalena; Corbella Sanahuja, Ignasi; Panciera, Rocco; Rudiger, Chris; Kerr, Yann H.; Walker, Jeff
    IEEE International Geoscience and Remote Sensing Symposium
    p. 3156-3166
    DOI: 10.1109/TGRS.2011.2120615
    Presentation's date: 2011-07-28
    Presentation of work at congresses

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Phase error assessment of MIRAS/SMOS by means of the redundant space calibration

     Dávila, Rubén; Torres Torres, Francisco; Duffo Ubeda, Nuria; Corbella Sanahuja, Ignasi; Pablos, Miriam; Martín Neira, Manuel
    IEEE International Geoscience and Remote Sensing Symposium
    p. 3756-3759
    DOI: 10.1109/IGARSS.2011.6050042
    Presentation's date: 2011-07
    Presentation of work at congresses

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    SMOS is the acronym for the Soil Moisture and Ocean Salinity mission by the European Space Agency (ESA) [1]. Its single payload, the Microwave Imaging Radiometer using Aperture Synthesis (MIRAS), was successfully launched in November 2009. A six months Commissioning Phase was devoted to bring the satellite into a fully operational condition and to characterize the payload using specific orbits to check all instrument modes [2]. An ongoing activity is devoted to analyze the contribution of each single calibration procedure to the overall radiometric accuracy in order to assess the dominant sources of spatial errors. In this framework, this paper is devoted to assess the performance of the phase calibration procedures by means of the so called Redundant Space Calibration (RSC)1.

  • Correction of spatial errors in SMOS brightness temperature images

     Wu, Lin; Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Duffo Ubeda, Nuria; Martín Neira, Manuel
    IEEE International Geoscience and Remote Sensing Symposium
    p. 3752-3755
    DOI: 10.1109/IGARSS.2011.6050041
    Presentation's date: 2011-07
    Presentation of work at congresses

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    Systematic spatial errors in SMOS brightness temperature images are successfully estimated by using a statistical analysis of measured data. A constant multiplicative mask is derived by averaging spatial errors of a large number of snapshots over the ocean. The mask has been obtained for the aliasfree field of view region without the need of any geophysical model. It can be considered as part of the instrument characterization and is totally independent of the target to measure. When this mask is applied to regular SMOS brightness temperatures, the spatial artifacts are clearly reduced.

  • Interferometric radiometry measurement concept: The visibility equation

     Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Duffo Ubeda, Nuria; Martín Neira, Manuel
    IEEE International Geoscience and Remote Sensing Symposium
    p. 3491-3494
    DOI: 10.1109/IGARSS.2011.6049973
    Presentation's date: 2011-07
    Presentation of work at congresses

    Read the abstract Read the abstract View View Open in new window  Share Reference managers Reference managers Open in new window

    The fundamental concept of interferometric aperture synthesis microwave radiometry for Earth observation is reviewed. The measurement principles and a discussion on the signal processing techniques for image reconstruction are briefly summarized. Examples of real measurements from the sensor onboard the ESA SMOS mission are used to illustrate the image reconstruction techniques.

  • First results on MIRAS calibration and overall SMOS performance

     Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Duffo Ubeda, Nuria; González Gambau, Veronica; Pablos Hernandez, Miriam; Duran Martínez, Israel; Martín Neira, Manuel
    Specialist Meeting on Microwave Radiometry and Remote Sensing of the Environment
    p. 1-4
    DOI: 10.1109/MICRORAD.2010.5559600
    Presentation's date: 2010-03-01
    Presentation of work at congresses

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Access to the full text
    Some results on SMOS-MIRAS calibration and Imaging  Open access

     Martín Neira, Manuel; Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Cabot, François; Duffo Ubeda, Nuria; Closa Dominguez, Josep M.; Kainulainen, Juha; Castro, R.; Barbosa Torralbo, José; Gutierrez, A.; Martín Porqueras, Fernando; Oliva, R.; Anterrieu, E.; Brown, N.; McMulan, K.
    IEEE International Geoscience and Remote Sensing Symposium
    p. 3768-3771
    DOI: 10.1109/IGARSS.2010.5651518
    Presentation's date: 2010-07-23
    Presentation of work at congresses

    Read the abstract Read the abstract Access to the full text Access to the full text Open in new window  Share Reference managers Reference managers Open in new window

    The performance requirements of the SMOS payload are demanding in terms of spatial resolution, accuracy, stability and precision, all critical to fulfill its scientific objectives. For this reason a commissioning plan for MIRAS was carefully devised to verify, calibrate and characterize all instrument parameters which could have an impact on its performance. This presentation describes the most important results from the instrument commissioning phase.

  • One point calibration in interferometric radiometers: MIRAS/SMOS preliminary results

     Torres Torres, Francisco; Corbella Sanahuja, Ignasi; Duffo Ubeda, Nuria; González Gambau, Veronica; Pablos Hernandez, Miriam; Duran Martínez, Israel; Martín Neira, Manuel
    Specialist Meeting on Microwave Radiometry and Remote Sensing of the Environment
    p. 243-246
    DOI: 10.1109/MICRORAD.2010.5559553
    Presentation's date: 2010-03-01
    Presentation of work at congresses

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Smos payload performance assessment

     Martín Neira, Manuel; Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Cabot, François; Closa Dominguez, Josep M.; Kainulainen, Juha; Castro, J.; Barbosa Torralbo, José; Gutierrez, A.; Martín Porqueras, Fernando; Oliva, R.; Anterrieu, E.; Brown, N.; McMulan, K.
    IEEE International Geoscience and Remote Sensing Symposium
    p. 3150-3153
    DOI: 10.1109/IGARSS.2010.5649704
    Presentation's date: 2010-07-25
    Presentation of work at congresses

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • SMOS payload in-orbit performance

     Martín Neira, Manuel; Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Duffo Ubeda, Nuria; Gonzalez Gambau, Verónica; Closa, Josep; Benito, Javier; Borges, A.; Rautiainen, K.; Kainulainen, Juha; Gutierrez, A.; Barbosa Torralbo, José; Catarino, N.; Castro, R.; Freitas, S.; Candeias, H.; Freitas, J.; Cabot, François; Anterrieu, E.; Zundo, M.; Brown, M.; McMullan, K.; Martín-Porqueras, F.; Oliva, R.; Wright, N.; Caprolicchio, R.
    European Geosciences Union General Assembly
    p. 1
    Presentation's date: 2010-06-02
    Presentation of work at congresses

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Access to the full text
    Correlation denormalization in interferometric or polarametric radiometers: a unified approach  Open access

     Colliander, A; Torres Torres, Francisco; Corbella Sanahuja, Ignasi
    IEEE transactions on geoscience and remote sensing
    Vol. 47, p. 561-568
    Date of publication: 2009-02
    Journal article

    Read the abstract Read the abstract Access to the full text Access to the full text Open in new window  Share Reference managers Reference managers Open in new window

    This paper presents a general analysis of correlation measurements in an interferometer or a radiometer based on noise injection and/or switching and measurement of normalized correlations (e.g., imaging synthetic aperture or polarimetric radiometers). A compact unifying notation for denormalizing the measured normalized correlations in the presence of noise injection in one or both of the receiving channels is presented. Technological limitations are also assessed by evaluating the effect of associated approximations. Finally, the approach is validated by experimental results of the measurement and calibration of related front-end nonidealities, namely, the finite isolation of the front-end switch. The methods presented in this paper are illustrated by a thorough analysis of the so-called mixed baselines of microwave imaging radiometer using aperture synthesis, which refer to those baselines which are formed between the regular receivers (light-weight cost-efficient front-end) and the reference radiometers. These baselines require special attention, since the reference radiometers are noise-injection radiometers, which inject noise to the measured signal, whereas the regular receivers are total power receivers.

  • Access to the full text
    On-ground characterization of the SMOS payload  Open access

     Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Duffo Ubeda, Nuria; Martín Neira, Manuel; González Gambau, Veronica; Camps Carmona, Adriano Jose; Vall-llossera Ferran, Mercedes Magdalena
    IEEE transactions on geoscience and remote sensing
    Vol. 47, num. 9, p. 3123-3133
    DOI: 10.1109/TGRS.2009.2016333
    Date of publication: 2009-09
    Journal article

    Read the abstract Read the abstract Access to the full text Access to the full text Open in new window  Share Reference managers Reference managers Open in new window

    The on-ground characterization of the synthetic aperture radiometer onboard the Soil Moisture and Ocean Salinity mission is described. Characterization includes basic functionality, internal calibration, thermal cycling, response to point and flat sources, self-radio-frequency interference, and others. The description of the different tests performed as well as the detailed results are provided. The results show that the instrument is very stable and has all gains and offsets consistent with the ones obtained at subsystem level. On the other hand, the phase of the visibility has a larger variation with temperature than expected, a small signal leakage from the local oscillators is present, and a small interference from the X-band transmitter during short periods of time has been detected. The implementation of internal-calibration procedures, along with the accurate thermal characterization performed, have been used to produce highly accurate brightness-temperature values well within specifications.

  • Access to the full text
    Polarimetric emission of rain events: simulation and experimental results at X-Band  Open access

     Duffo Ubeda, Nuria; Vall·Llosera, M; Camps Carmona, Adriano Jose; Corbella Sanahuja, Ignasi; Torres Torres, Francisco
    Remote Sensing
    Vol. 1, num. 2, p. 107-121
    DOI: 10.3390/rs1020107
    Date of publication: 2009-06
    Journal article

    Read the abstract Read the abstract Access to the full text Access to the full text Open in new window  Share Reference managers Reference managers Open in new window

    Accurate models are used today for infrared and microwave satellite radiance simulations of the first two Stokes elements in the physical retrieval, data assimilation etc. of surface and atmospheric parameters. Although in the past a number of theoretical and experimental works have studied the polarimetric emission of some natural surfaces, specially the sea surface roughened by the wind (Windsat mission), very limited studies have been conducted on the polarimetric emission of rain cells or other natural surfaces. In this work, the polarimetric emission (four Stokes elements) of a rain cell is computed using the polarimetric radiative transfer equation assuming that raindrops are described by Pruppacher-Pitter shapes and that their size distribution follows the Laws-Parsons law. The Boundary Element Method (BEM) is used to compute the exact bistatic scattering coefficients for each raindrop shape and different canting angles. Numerical results are compared to the Rayleigh or Mie scattering coefficients, and to Oguchi’s ones, showing that above 1-2 mm raindrop size the exact formulation is required to model properly the scattering. Simulation results using BEM are then compared to the experimental data gathered with a X-band polarimetric radiometer. It is found that the depolarization of the radiation caused by the scattering of non-spherical raindrops induces a non-zero third Stokes parameter, and the differential phase of the scattering coefficients induces a non-zero fourth Stokes parameter.

  • CONCEPTOS AVANZADOS EN TELEDETECCION ACTIVA Y PASIVA DE MICROONDAS: TECNOLOGIA Y APLICACIONES

     Torres Torres, Francisco; Aguasca Sole, Alberto; Duffo Ubeda, Nuria; Mallorqui Franquet, Jordi Joan; Broquetas Ibars, Antoni; Corbella Sanahuja, Ignasi; López Martínez, Carlos; Fabregas Canovas, Francisco Javier
    Competitive project

     Share

  • Brightness-Temperature Retrieval Methods in Synthetic Aperture Radiometers

     Corbella Sanahuja, Ignasi; Torres, F; Duffo Ubeda, Nuria; Camps Carmona, Adriano Jose; González, A.; Vail-Ilossera, M
    IEEE transactions on geoscience and remote sensing
    Vol. 47, num. 1, p. 285-294
    DOI: 10.1109/TGRS.2008.2002911
    Date of publication: 2009-01
    Journal article

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Linearity characterization of detectors for interferometric radiometers

     Gonzalez-Haro, Cristina; Torres Torres, Francisco; Duffo Ubeda, Nuria; Corbella Sanahuja, Ignasi; Vilaseca, R; de Paco Sánchez, Pedro Antonio; Martín Neira, Manuel
    IEEE International Geoscience and Remote Sensing Symposium
    p. IV-657-IV-660
    DOI: 10.1109/IGARSS.2009.5417462
    Presentation's date: 2009-07-12
    Presentation of work at congresses

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • MIRAS characterization and monitoring during the SMOS In-Orbit Commissioning Phase

     Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Martín Neira, Manuel; Duffo Ubeda, Nuria; Gonzalez Gambau, Verónica; Camps Carmona, Adriano Jose; Vall-llossera Ferran, Mercedes Magdalena
    European Geosciences Union General Assembly
    Presentation's date: 2009-04-19
    Presentation of work at congresses

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • SMOS payload pre-launch performance

     Martín Neira, Manuel; Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Duffo Ubeda, Nuria; Gonzalez Gambau, Verónica; Colliander, A; Closa, Josep; Benito, J; Borges, A; Brown, M; McMullan, K
    European Geosciences Union General Assembly
    Presentation's date: 2009-04-19
    Presentation of work at congresses

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Phase noise requirements in interferometric radiometers

     Torres Torres, Francisco; Corbella Sanahuja, Ignasi; Castro, E.; Segarra, M.; Vilaseca, R
    IEEE International Geoscience and Remote Sensing Symposium
    p. III-1027-III-1030
    DOI: 10.1109/IGARSS.2009.5417953
    Presentation's date: 2009-07-12
    Presentation of work at congresses

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • On-flight characterization of the SMOS payload during the commissioning phase

     Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Duffo Ubeda, Nuria; Camps Carmona, Adriano Jose; Vall-llossera Ferran, Mercedes Magdalena; González Gambau, Veronica
    IEEE International Geoscience and Remote Sensing Symposium
    p. V-180-V-183
    DOI: 10.1109/IGARSS.2009.5417701
    Presentation's date: 2009-09-12
    Presentation of work at congresses

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • One point calibration in interferometric radiometers: error assessment

     Torres Torres, Francisco; Corbella Sanahuja, Ignasi; Duffo Ubeda, Nuria; González Gambau, Veronica
    IEEE International Geoscience and Remote Sensing Symposium
    p. III-1035-III-1038
    DOI: 10.1109/IGARSS.2009.5417955
    Presentation's date: 2009-07-12
    Presentation of work at congresses

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • SMOS calibration

     Brown, M A; Torres Torres, Francisco; Corbella Sanahuja, Ignasi; Colliander, A
    IEEE transactions on geoscience and remote sensing
    Vol. 46, num. 3, p. 646-658
    DOI: 10.1109/TGRS.2007.914810
    Date of publication: 2008-03
    Journal article

    View View Open in new window  Share Reference managers Reference managers Open in new window

  • Brightness temperature retrievals from the small airborne MIRAS

     Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Duffo Ubeda, Nuria; Camps Carmona, Adriano Jose; Vall-llossera Ferran, Mercedes Magdalena
    IEEE International Geoscience & Remote Sensing Symposium
    p. 1-4
    Presentation of work at congresses

     Share Reference managers Reference managers Open in new window

  • Fast processing tool for SMOS data

     Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Duffo Ubeda, Nuria; Gonzalez Gambau, Verónica; Camps Carmona, Adriano Jose; Vall-llossera Ferran, Mercedes Magdalena
    IEEE International Geoscience & Remote Sensing Symposium
    p. 1-4
    Presentation's date: 2008-07-07
    Presentation of work at congresses

     Share Reference managers Reference managers Open in new window