Graphic summary
  • Show / hide key
  • Information


Scientific and technological production
  •  

1 to 50 of 265 results
  • 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
    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.

  • 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
    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.

  • 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
    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.

  • 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
    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.

  • 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
    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
    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.

  • 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
    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

  • 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
    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.

  • 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
    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
    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
    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
    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.

  • 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
    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
    Date of publication: 2012-09
    Journal article

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

  • 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
    Date of publication: 2012-01
    Journal article

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

  • 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
    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.

  • 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
    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

  • 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
    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.

  • 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
    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
    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.

  • 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
    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.

  • 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
    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.

  • 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; Ruediger, Christoph; Kerr, Yann H.; Walker, Jeffrey
    IEEE transactions on geoscience and remote sensing
    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.

  • 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
    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

  • 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
    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
    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

  • 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
    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

  • MULTISCALE SOIL MOISTURE RETRIEVALS FROM MICROWAVE REMOTE SENSING OBSERVATIONS  Open access  awarded activity

     Piles Guillem, Maria
    Defense's date: 2010-07-16
    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

    La humedad del suelo es la variable que regula los intercambios de agua, energía, y carbono entre la tierra y la atmósfera. Mediciones precisas de humedad son necesarias para una gestión sostenible de los recursos hídricos, para mejorar las predicciones meteorológicas y climáticas, y para la detección y monitorización de sequías e inundaciones. Esta tesis se centra en la medición de la humedad superficial de la Tierra desde el espacio, a escalas global y regional. Estudios teóricos y experimentales han demostrado que la teledetección pasiva de microondas en banda L es optima para la medición de humedad del suelo, debido a que la atmósfera es transparente a estas frecuencias, y a la relación directa de la emisividad del suelo con su contenido de agua. Sin embargo, el uso de la teledetección pasiva en banda L ha sido cuestionado en las últimas décadas, pues para conseguir la resolución temporal y espacial requeridas, un radiómetro convencional necesitaría una gran antena rotatoria, difícil de implementar en un satélite. Actualmente, hay tres principales propuestas para abordar este problema: (i) el uso de un radiómetro de apertura sintética, que es la solución implementada en la misión Soil Moisture and Ocean Salinity (SMOS) de la ESA, en órbita desde noviembre del 2009; (ii) el uso de un radiómetro ligero de grandes dimensiones y un rádar operando en banda L, que es la solución que ha adoptado la misión Soil Moisture Active Passive (SMAP) de la NASA, con lanzamiento previsto en 2014; (iii) el desarrollo de técnicas de desagregación de píxel que permitan mejorar la resolución espacial de las observaciones. La primera parte de la tesis se centra en el estudio del algoritmo de recuperación de humedad del suelo a partir de datos SMOS, que es esencial para obtener estimaciones de humedad con alta precisión. Se analizan diferentes configuraciones con datos simulados, considerando (i) la opción de añadir información a priori de los parámetros que dominan la emisión del suelo en banda L —humedad, rugosidad, temperatura del suelo, albedo y opacidad de la vegetación— con diferentes incertidumbres asociadas, y (ii) el uso de la polarización vertical y horizontal por separado, o del primer parámetro de Stokes. Se propone una configuración de recuperación de humedad óptima para SMOS. La resolución espacial de los radiómetros de SMOS y SMAP (40-50 km) es adecuada para aplicaciones globales, pero limita la aplicación de los datos en estudios regionales, donde se requiere una resolución de 1-10 km. La segunda parte de esta tesis contiene tres novedosas propuestas de mejora de resolución espacial de estos datos: • Se ha desarrollado un algoritmo basado en la deconvolución de los datos SMOS que permite mejorar la resolución espacial de las medidas. Los resultados de su aplicación a datos simulados y a datos obtenidos con un radiómetro aerotransportado muestran que es posible mejorar el producto de resolución espacial y resolución radiométrica de los datos. • Se presenta un algoritmo para mejorar la resolución espacial de las estimaciones de humedad de SMOS utilizando datos MODIS en el visible/infrarrojo. Los resultados de su aplicación a algunas de las primeras imágenes de SMOS indican que la variabilidad espacial de la humedad del suelo se puede capturar a 32, 16 y 8 km. • Un algoritmo basado en detección de cambios para combinar los datos del radiómetro y el rádar de SMAP en un producto de humedad a 10 km ha sido desarrollado y validado utilizando datos simulados y datos experimentales aerotransportados. Este trabajo se ha desarrollado en el marco de las actividades preparatorias de SMOS y SMAP, los dos primeros satélites dedicados a la monitorización de la variación temporal y espacial de la humedad de la Tierra. Los resultados presentados contribuyen a la obtención de estimaciones de humedad del suelo con la precisión y la resolución espacial necesarias para un mejor conocimiento del ciclo del agua y una mejor gestión de los recursos hídricos.

    Soil moisture is a key state variable of the Earth's system; it is the main variable that links the Earth's water, energy and carbon cycles. Accurate observations of the Earth's changing soil moisture are needed to achieve sustainable land and water management, and to enhance weather and climate forecasting skill, flood prediction and drought monitoring. This Thesis focuses on measuring the Earth's surface soil moisture from space at global and regional scales. Theoretical and experimental studies have proven that L-band passive remote sensing is optimal for soil moisture sensing due to its all-weather capabilities and the direct relationship between soil emissivity and soil water content under most vegetation covers. However, achieving a temporal and spatial resolution that could satisfy land applications has been a challenge to passive microwave remote sensing in the last decades, since real aperture radiometers would need a large rotating antenna, which is difficult to implement on a spacecraft. Currently, there are three main approaches to solving this problem: (i) the use of an L-band synthetic aperture radiometer, which is the solution implemented in the ESA Soil Moisture and Ocean Salinity (SMOS) mission, launched in November 2009; (ii) the use of a large lightweight radiometer and a radar operating at L-band, which is the solution adopted by the NASA Soil Moisture Active Passive (SMAP) mission, scheduled for launch in 2014; (iii) the development of pixel disaggregation techniques that could enhance the spatial resolution of the radiometric observations. The first part of this work focuses on the analysis of the SMOS soil moisture inversion algorithm, which is crucial to retrieve accurate soil moisture estimations from SMOS measurements. Different retrieval configurations have been examined using simulated SMOS data, considering (i) the option of adding a priori information from parameters dominating the land emission at L-band —soil moisture, roughness, and temperature, vegetation albedo and opacity— with different associated uncertainties and (ii) the use of vertical and horizontal polarizations separately, or the first Stokes parameter. An optimal retrieval configuration for SMOS is suggested. The spatial resolution of SMOS and SMAP radiometers (~ 40-50 km) is adequate for global applications, but is a limiting factor to its application in regional studies, where a resolution of 1-10 km is needed. The second part of this Thesis contains three novel downscaling approaches for SMOS and SMAP: • A deconvolution scheme for the improvement of the spatial resolution of SMOS observations has been developed, and results of its application to simulated SMOS data and airborne field experimental data show that it is feasible to improve the product of the spatial resolution and the radiometric sensitivity of the observations by 49% over land pixels and by 30% over sea pixels. • A downscaling algorithm for improving the spatial resolution of SMOS-derived soil moisture estimates using higher resolution MODIS visible/infrared data is presented. Results of its application to some of the first SMOS images show the spatial variability of SMOS-derived soil moisture observations is effectively captured at the spatial resolutions of 32, 16, and 8 km. • A change detection approach for combining SMAP radar and radiometer observations into a 10 km soil moisture product has been developed and validated using SMAP-like observations and airborne field experimental data. This work has been developed within the preparatory activities of SMOS and SMAP, the two first-ever satellites dedicated to monitoring the temporal and spatial variation on the Earth's soil moisture. The results presented contribute to get the most out of these vital observations, that will further our understanding of the Earth's water cycle, and will lead to a better water resources management.

  • 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
    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
    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

  • 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
    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

  • 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
    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
    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

  • 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
    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.

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

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

     Share

  • 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
    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
    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.

  • Determination of the sea surface emissivity at L-band and application to SMOS salinity retrieval algorithms: Review of the contributions of the UPC-ICM

     Camps Carmona, Adriano Jose; Font, J; Vall-llossera Ferran, Mercedes Magdalena; Corbella Sanahuja, Ignasi; Duffo Ubeda, Nuria; Torres Torres, Francisco; Blanch Boris, Sebastian; Aguasca Sole, Alberto; Villarino, R; Gabarro, C; Enrique, L; Miranda, J; Sabia, Roberto
    Radio science
    Date of publication: 2008-06-20
    Journal article

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

  • AMIRAS - An Airborne MIRAS Demonstrator

     Martín Neira, Manuel; Cabeza, I; Perez, C; Palacios, M A; Guijarro, M A; Ribó Vedrilla, Serni; Corbella Sanahuja, Ignasi; Blanch Boris, Sebastian; Torres Torres, Francisco; Duffo Ubeda, Nuria; Gonzalez Gambau, Verónica; Beraza, S; Camps Carmona, Adriano Jose; Vall-llossera Ferran, Mercedes Magdalena
    IEEE transactions on geoscience and remote sensing
    Date of publication: 2008-03
    Journal article

     Share Reference managers Reference managers Open in new window

  • Angular and radiometric resolution of Y-shaped non-uniform synthetic aperture radiometers for Earth observation

     Camps Carmona, Adriano Jose; Vall-llossera Ferran, Mercedes Magdalena; Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Duffo Ubeda, Nuria
    IEEE Geoscience and Remote Sensing Letters
    Date of publication: 2008-10
    Journal article

     Share Reference managers Reference managers Open in new window

  • Interferometric radiometers: fringe washing function estimation

     Duffo Ubeda, Nuria; Corbella Sanahuja, Ignasi; Torres Torres, Francisco; González Gambau, Veronica; Martín Neira, Manuel
    IEEE International Geoscience and Remote Sensing Symposium
    Presentation's date: 2008-07-07
    Presentation of work at congresses

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

  • MIRAS-SMOS Antenna Relative Phase Calibration

     Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Benito Paramo, Jose Antonio; Martín Neira, Manuel
    IEEE International Symposium on Antennas and Propagation
    Presentation of work at congresses

     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
    Date of publication: 2008-03
    Journal article

     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
    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
    Presentation's date: 2008-07-07
    Presentation of work at congresses

     Share Reference managers Reference managers Open in new window

  • Improving the spatial resolution of synthetic aperture radiometer imagery using auxiliary information: application to the SMOS mission

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

     Share Reference managers Reference managers Open in new window

  • MIRAS ground characterization

     Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Duffo Ubeda, Nuria; Martín Neira, Manuel; Gonzalez Gambau, Verónica; Camps Carmona, Adriano Jose; Vall-llossera Ferran, Mercedes Magdalena
    Microwave Radiometry and Remote Sensing of the Environment, 2008. MICRORAD 2008
    Presentation of work at congresses

     Share Reference managers Reference managers Open in new window

  • Improved Image Reconstruction Algorithms for Aperture Synthesis Radiometers

     Camps Carmona, Adriano Jose; Vall-llossera Ferran, Mercedes Magdalena; Corbella Sanahuja, Ignasi; Duffo Ubeda, Nuria; Torres Torres, Francisco
    IEEE transactions on geoscience and remote sensing
    Date of publication: 2008-01
    Journal article

     Share Reference managers Reference managers Open in new window

  • Diccionari de Telecomunicacions

     Aguilar Igartua, Mónica; Alcober Segura, Jesus Angel; Altes Bosch, Jorge; Aragones Cervera, Xavier; Artigas Garcia, David; Bardes Llorensi, Daniel; Barlabe Dalmau, Antoni; Bragos Bardia, Ramon; Calderer Cardona, Josep; Cardama Aznar, Angel; Casademont Serra, Jordi; Casals Ibañez, Lluis; Comeron Tejero, Adolfo; Cotrina Navau, Josep; Cruz Llopis, Luis Javier de La; Dios Otin, Victor Federico; Duxans Barrobes, Helena; Esparza Martin, Oscar; Esquerra Llucià, Ignasi; Garcia Vizcaino, David; Garcies Salva, Pau; Gomez Montenegro, Carlos; Gorricho Moreno, Juan Luis; Guinjoan Gispert, Francisco; Hesselbach Serra, Xavier; Liria Righetti, Antoni; Lopez Salcedo, Jose Antonio; Madrenas Boadas, Jordi; Madueño Ruiz, María Isabel; Mestre Pons, Francesc Xavier; Monte Moreno, Enrique; Morros Rubió, Josep Ramon; Muñoz Tapia, Jose Luis; Pallares Segarra, Esteve; Pons Nin, Joan; Recolons Martos, Jaume; Rincon Rivera, David; Riu Costa, Pere Joan; Ruiz Vela, Inmaculada; Pradell Cara, Lluis; Pascual Iserte, Antonio; Prat Viñas, Luis; Rey Micolau, Francesc; Villares Piera, N. Javier
    Date of publication: 2007-03
    Book

     Share Reference managers Reference managers Open in new window

  • Some results of the MIRAS-SMOS demonstrator campaigns

     Duffo Ubeda, Nuria; Torres Torres, Francisco; Corbella Sanahuja, Ignasi; Gonzalez Gambau, Verónica; Blanch Boris, Sebastian; Camps Carmona, Adriano Jose; Vall-llossera Ferran, Mercedes Magdalena; Alvarez Muñoz, Jose Luis; Ribó Vedrilla, Serni; Martín Neira, Manuel
    IEEE international Geoscience and Remote Sensing Symposium
    Presentation's date: 2007-06-23
    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

    In this paper, some results of the MIRAS-SMOS demonstrator campaigns are presented. The follow two campaigns were held: an image validation campaign at IRTA side and a flight demonstrator campaign at Finland. The ultimate objective of the airborne demonstrator is to demonstrate its imaging capabilities by applying improved calibration and inversion algorithms to natural low-contrast targets. © 2007 IEEE.