24 results on '"Font, Jordi"'
Search Results
2. Surface Salinity in the North Atlantic Subtropical Gyre : During the STRASSE/SPURS Summer 2012 Cruise
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Reverdin, Gilles, Morisset, Simon, Marié, Louis, Bourras, Denis, Sutherland, Graigory, Ward, Brian, Salvador, Joaquín, Font, Jordi, Cuypers, Yannis, Centurioni, Luca, Hormann, Verena, Koldziejczyk, Nicolas, Boutin, Jacqueline, D'Ovidio, Francesco, Nencioli, Francesco, Martin, Nicolas, Diverres, Denis, Alory, Gaël, and Lumpkin, Rick
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- 2015
3. Surpact : A SMOS Surface Wave Rider for Air-Sea Interaction
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REVERDIN, GILLES, MORISSET, SIMON, BOURRAS, DENIS, MARTIN, NICOLAS, LOURENÇO, ANTONIO, BOUTIN, JACQUELINE, CAUDOUX, CHRISTOPHE, FONT, JORDI, and SALVADOR, JOAQUÍN
- Published
- 2013
4. Advances in instrumented Lagrangian buoys
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Fernández Gallego, Pedro, Salvador, Joaquín, Font, Jordi, Pelegrí, Josep Lluís, and García-Ladona, Emilio
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Salinity ,Temperatures ,Oceanographic instrumentation ,Surface drifters ,Lagrangian buoys - Abstract
5th Internacional Workshop on Marine Technology (MARTECH 2013), 9-11 October 2013, Girona, From 2005 the ICM-CSIC has designed, built and tested surface drifting buoys for the measurement of several oceanographic parameters, mainly temperature and salinity. These prototypes have evolved and been adapted to different sampling needs and strategies. We are presenting here the main characteristics and capabilities of the last developments, The design and construction of buoys at ICM-CSIC has been funded by different research projects. During the last two years three projects have supported the recent developments (MIDAS-6, Spanish I+D+i National Plan AYA2010-22062-C05-01; TIC-MOC, Spanish I+D+i National Plan CTM2011-28867; TOSCA, European Regional Development Fund MED Programme G-MED09- 425)
- Published
- 2013
5. A new buoy for measurement and real time transmission of surface salinity
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Salvador, Joaquín, Fernández Gallego, Pedro, Julià Brugues, Agustí, Font, Jordi, and Pelegrí, Josep Lluís
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Salinity ,Temperatures ,Instruments and techniques - Abstract
39th CIESM Congress, Venise, Italie.-- 1 page, 2 figures, A surface buoy has been designed to measure temperature and salinity with high accuracy and transmit the data by satellite for a long period of time in studies of mesoscale or long scale oceanography. Prototypes have been built and tested in two different versions: to collect data close to the surface or at a depth of 100-150 m depending on the objectives of the experiment. These buoys are mainly used for Lagrangian measurements after being released from a vessel, although long duration tests have also been made with moored units mainly in the NW Mediterranean, This technological development has been mainly funded by the Spanish National R+D Plan through projects CANOA (CTM2005-00444/MAR) and MIDAS-4 (ESP2005-06823-C05)
- Published
- 2010
6. Retrieving ocean salinity from SMOS microwave radiometric measurements
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Font, Jordi
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Salinity ,Surface waters ,Remote sensing ,Open sea - Abstract
39th CIESM Congress, Venise, Italie.-- 1 page, 1 figure, SMOS (Soil Moisture and Ocean Salinity) is an Earth observation satellite from the European Space Agency launched in November 2009. It is the first satellite mission addressing the challenge of measuring sea surface salinity, never attempted before due to its technical complexity. It uses a microwave interferometric radiometer with aperture synthesis that generates brightness temperature images at 1.4 GHz, from which both geophysical variables are derived using their influence on the dielectric constant of the emitting body, land or ocean. This paper presents the principles of operation of the instrument, the algorithmic approach implemented for the retrieval of salinity from the observations, and the limitations for the use of SMOS products in the Mediterranean, The development of SMOS has been a collective effort coordinated by ESA of many scientists and technologists as well as industrial companies from several countries, especially Spain and France. This paper is a contribution to the SMOS Barcelona Expert Centre and project ESP2007-65667-C04 funded by the Spanish Ministry of Science and Innovation
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- 2010
7. Determination of the sea surface emissivity at L-band and application to SMOS salinity retrieval algorithms: Review of the contributions of the UPC-ICM
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Camps, Adriano, Font, Jordi, Vall-llossera, Mercè, Corbella, I., Duffo, N., Torres, F., Blanch, S., Aguasca, A., Villarino, R., Gabarró, Carolina, Enrique, L., Miranda, J., Sabia, Roberto, and Talone, Marco
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Salinity ,Retrieval ,Microwave radiometry - Abstract
14 pages, 17 figures, This work describes the main effects that have to be taken into account to model the sea surface emission at L-band, and the existing approaches to perform the sea surface salinity retrieval from multiangular radiometric measurements. This manuscript reviews the activities carried out in these fields during the past years by the Universitat Politècnica de Catalunya (UPC) in collaboration with the Institut de Ciències del Mar (ICM - CSIC). They cover the precise measurement of the dielectric permittivity of the seawater at L-band, the sea surface emissivity (including the effect of wind-driven waves, swell, currents, rain, and oil spills), the comparison of experimental data with numerical models, and the development of sea surface salinity retrieval algorithms for SMOS using multiangular radiometric data. The first salinity retrievals using 2D aperture synthesis radiometry are also presented, This work has been supported by ESA Projects ESA, ESTEC contract 141888/00/NL/DC, CCN-1 and CCN2, ESA contract 18176/04/NL/CB, and Spanish Research projects and EU FEDER CICYT TIC 99-1050-C03-01, TIC2002-04451-C02-01, TEC2005-06863-C02-01, PNE-009/2001-C-02, ESP2002-11648-E, ESP2004-00671, and ESP2005-06823-C05
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- 2008
8. SMOS: Measuring Sea Surface Salinity from Space
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Gabarró Prats, Carolina, Font, Jordi, and Talone, Marco
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Sea surface ,Salinity ,Sadiometry ,Enginyeria de la telecomunicació [Àrees temàtiques de la UPC] ,Synthetic aperture ,SMOS - Abstract
Martech 2007 International Workshop on Marine Technology, 15-16 november 2007, Vilanova i la Geltrú, Spain.-- 2 pages, In May 1999, the European Space Agency (ESA) selected SMOS as an Earth Explorer Opportunity mission. One of its goals is the generation of global Sea Surface Salinity (SSS) maps. The sensor embarked is an L-band interferometric radiometer with full-polarimetric capability called MIRAS. The retrieval of SSS from microwave measurements is based on the fact that the brightness temperature (TB) of seawater is a function of the dialectric constant, temperature and sea surface state (roughness, foam,...). The sensitivity of TB to SSS is maximum at L-band, but it is necessary to quantify the other effects to have a reliable SSS retrieval. In order to improve the present understanding of these effects on TB, ESA sponsored to WISE (Wind and Salinity Experiment) 2000 and 2001 and EuroSTARS field campaigns. These experimental results are of great importance for the development of sea surface emissivity models that will be used in the future SMOS SSS retrieval algorithms. This paper presents an overview of campaign performed as well as the activities there has been developed
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- 2007
9. La misión SMOS de la ESA medirá a partir de 2007 la salinidad superficial del océano
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Font, Jordi and Camps, Adriano
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Salinity ,Circulación oceánica global ,Microondas ,Global ocean circulation ,Radiometría interferométrica ,Interferometric radiometry ,Salinidad ,Microwaves ,ESA - Abstract
5 pages, 2 figures, [EN] The European Space Agency SMOS (Soil Moisture and Ocean Salinity) mission aims at obtaining global maps of both variables from space for large scale and climatic studies. It uses an L-band microwave interferometric radiometer with aperture synthesis (MIRAS) to measure the brightness temperature (Tb) emitted by the Earth’s surface and then computes from it the two geophysical parameters. The retrieval of salinity is a complex process that requires the knowledge of other environmental information, as sea surface temperature and roughness, and an accurate processing of the radiometer measurements, [ES] La misión SMOS (Soil Moisture and Ocean Salinity, Humedad del Suelo y Salinidad de los Océanos) de la Agencia Espacial Europea tiene el objetivo de obtener mapas globales de ambas variables desde el espacio para estudios climáticos y de gran escala. Usa un radiómetro interferométrico en la banda L de microondas (MIRAS) para medir la temperatura de brillo (Tb) emitida por la superficie terrestre, y a partir de ella calcula las dos variables geofísicas. La salinidad se obtiene mediante un proceso complejo de los datos radiométricos que requiere información sobre otros parámetros ambientales como temperatura y rugosidad de la superficie del mar, La participación española en SMOS ha sido posible gracias a la financiación del Centro para el Desarrollo Tecnológico Industrial (CDTI) y el Programa Nacional del Espacio. Este artículo es una contribución al proyecto ESP2004-00671
- Published
- 2006
10. The Determination of Surface Salinity with the European SMOS Space Mission
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Font, Jordi, Lagerloef, Gary S. E., Le Vine, David M., Camps Carmona, Adriano José, Zanifé, Ouan-Zan, Universitat Politècnica de Catalunya. Departament de Teoria del Senyal i Comunicacions, and Universitat Politècnica de Catalunya. RSLAB - Grup de Recerca en Teledetecció
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Salinity ,Astrophysics::Instrumentation and Methods for Astrophysics ,Microwave radiometry ,Oceanography ,Physics::Atmospheric and Oceanic Physics ,Physics::Geophysics - Abstract
The European Space Agency Soil Moisture and Ocean Salinity (SMOS) mission aims at obtaining global maps of soil moisture and sea surface salinity from space for large-scale and climatic studies. It uses an L-band (1400–1427 MHz) Microwave Interferometric Radiometer by Aperture Synthesis to measure brightness temperature of the earth’s surface at horizontal and vertical polarizations ( h and v). These two parameters will be used together to retrieve the geophysical parameters. The retrieval of salinity is a complex process that requires the knowledge of other environmental information and an accurate processing of the radiometer measurements. Here, we present recent results obtained from several studies and field experiments that were part of the SMOS mission, and highlight the issues still to be solved.
- Published
- 2004
11. WISE 2000: Can we measure salinity from a satellite?
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Font, Jordi, Emelianov, Mikhail, Gabarró, Carolina, Julià Brugues, Agustí, and Moll, Michael
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Salinity ,Air-sea interactions ,Instruments and techniques ,Remote sensing - Abstract
Font, Jordi... et al.-- 1 page, Satellite observation of ocean salinity has not been possible until now due to the challenge of ?ying a microwave radiometer able to detect sea surface emission variations related to salinity.The European Space Agency SMOS mission is the first attempt to solve this problem. A new radiometric concept and recent improvements in understanding the processes that modify the ocean water emissivity have made it possible. The WISE 2000 campaign has been conducted in the NW Mediterranean to obtain radiometric and in situ data to improve the understanding of the sea state effect on the sea surface L-band microwave emissivity
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- 2001
12. Impact of the Local Oscillator Calibration Rate on the SMOS Measurements and Retrieved Salinities.
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Gabarro, Carolina, Gonzalez-Gambau, Veronica, Corbella, Ignasi, Torres, Francesc, Martinez, Justino, Portabella, Marcos, and Font, Jordi
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SOIL moisture measurement ,MEASUREMENT of salinity ,SEAWATER salinity ,DIGITAL signal processing ,BRIGHTNESS temperature ,MICROWAVE imaging equipment - Abstract
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 LO calibration 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 \pm0.3 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 2 min 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. [ABSTRACT FROM AUTHOR]
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- 2013
- Full Text
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13. SMOS first data analysis for sea surface salinity determination.
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Font, Jordi, Boutin, Jacqueline, Reul, Nicolas, Spurgeon, Paul, Ballabrera-Poy, Joaquim, Chuprin, Andrei, Gabarró, Carolina, Gourrion, Jérôme, Guimbard, Sébastien, Hénocq, Claire, Lavender, Samantha, Martin, Nicolas, Martínez, Justino, McCulloch, Michael, Meirold-Mautner, Ingo, Mugerin, César, Petitcolin, François, Portabella, Marcos, Sabia, Roberto, and Talone, Marco
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SOIL moisture , *SEAWATER salinity , *DATA analysis , *SALINITY , *INTERFEROMETERS , *ELECTRONIC data processing - Abstract
Soil Moisture and Ocean Salinity (SMOS), launched on 2 November 2009, is the first satellite mission addressing sea surface salinity (SSS) measurement from space. Its unique payload is the Microwave Imaging Radiometer using Aperture Synthesis (MIRAS), a new two-dimensional interferometer designed by the European Space Agency (ESA) and operating at the L-band frequency. This article presents a summary of SSS retrieval from SMOS observations and shows initial results obtained one year after launch. These results are encouraging, but also indicate that further improvements at various data processing levels are needed and hence are currently under investigation. [ABSTRACT FROM PUBLISHER]
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- 2013
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14. The SMOS Mission: New Tool for Monitoring Key Elements of the Global Water Cycle.
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KERR, YANN H., WALDTEUFEL, PHILIPPE, WIGNERON, JEAN-PIERRE, DELWART, STEVEN, CABOT, FRANÇOIS, BOUTIN, JACQUELINE, ESCORIHUELA, MARIA-JOSÉ, FONT, JORDI, REUL, NICOLAS, GRUHIER, CLAIRE, JUGLEA, SILVIA ENACHE, DRINKWATER, MARK R., HAHNE, ACHIM, MARTÍN-NEIRA, MANUEL, and MECKLENBURG, SUSANNE
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INTERFEROMETRY ,RADIOMETERS ,SOIL moisture ,SALINITY ,WATER chemistry ,HYDROLOGIC cycle ,CLIMATE change ,ARTIFICIAL satellites in earth sciences - Abstract
It is now well understood that data on soil moisture and sea surface salinity (SSS) are required to improve meteorological and climate predictions. These two quantities are not yet available globally or with adequate temporal or spatial sampling. It is recognized that a spaceborne L-band radiometer with a suitable antenna is the most promising way of fulfilling this gap. With these scientific objectives and technical solution at the heart of a proposed mission concept the European Space Agency (ESA) selected the Soil Moisture and Ocean Salinity (SMOS) mission as its second Earth Explorer Opportunity Mission. The development of the SMOS mission was led by ESA in collaboration with the Centre National d'Etudes Spatiales (CNES) in France and the Centro para el Desarrollo Tecnologico Industrial (CDTI) in Spain. SMOS carries a single payload, an L-Band 2-D interferometric radiometer operating in the 1400-1427-MHz protected band [1]. The instrument receives the radiation emitted from Earth's surface, which can then be related to the moisture content in the first few centimeters of soil over land, and to salinity in the surface waters of the oceans. SMOS will achieve an unprecedented maximum spatial resolution of 50 km at L-band over land (43 km on average over the field of view), providing multi-angular dual polarized (or fully polarized) brightness temperatures over the globe. SMOS has a revisit time of less than 3 days so as to retrieve soil moisture and ocean salinity data, meeting the mission's science objectives. The caveat in relation to its sampling requirements is that SMOS will have a somewhat reduced sensitivity when compared to conventional radiometers. The SMOS satellite was launched successfully on November 2, 2009. [ABSTRACT FROM AUTHOR]
- Published
- 2010
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15. SMOS: The Challenging Sea Surface Salinity Measurement From Space.
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FONT, JORDI, CAMPS, ADRIANO, BORGES, ANDRÉS, MARTÍN-NEIRA, MANUEL, BOUTIN, JACQUELINE, REUL, NICOLAS, KERR, YANN H., HAHNE, ACHIM, and MECKLENBURG, SUSANNE
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SOIL moisture ,SALINITY ,WATER chemistry ,MICROWAVE imaging ,MICROWAVE remote sensing ,SYNTHETIC apertures ,SURFACE of the earth - Abstract
Soil Moisture and Ocean Salinity, European Space Agency, is the first satellite mission addressing the challenge of measuring sea surface salinity from space. It uses an L-band microwave interferometric radiometer with aperture synthesis (MIRAS) that generates brightness temperature images, from which both geophysical variables are computed. The retrieval of salinity requires very demanding performances of the instrument in terms of calibration and stability. This paper highlights the importance of ocean salinity for the Earth's water cycle and climate; provides a detailed description of the MIRAS instrument, its principles of operation, calibration, and image-reconstruction techniques; and presents the algorithmic approach implemented for the retrieval of salinity from MIRAS observations, as well as the expected accuracy of the obtained results. [ABSTRACT FROM AUTHOR]
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- 2010
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16. Determination of the Sea Surface Salinity Error Budget in the Soil Moisture and Ocean Salinity Mission.
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Sabia, Roberto, Camps, Adriano, Talone, Marco, Vall-llossera, Mercè, and Font, Jordi
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SOIL moisture ,SALINITY ,CONDENSATION (Meteorology) ,OCEAN ,CONFIGURATION space - Abstract
The Soil Moisture and Ocean Salinity mission will provide sea surface salinity maps over the oceans, beginning in late 2009. In this paper an ocean salinity error budget is described, an analysis needed to identify the magnitude of the error sources associated with the retrieval. Instrumental, external noise sources, and geophysical errors have been analyzed, stressing their relative impact. This paper includes results from previous studies, addressing the impact of multisource auxiliary sea surface temperature and wind speed data on the final salinity error. It provides, moreover, a sensitivity analysis to the uncertainty of the auxiliary salinity field. Salinity retrieval has been addressed in a wide set of configurations of the inversion algorithm. [ABSTRACT FROM AUTHOR]
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- 2010
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17. Simulated SMOS Levels 2 and 3 Products: The Effect of Introducing ARGO Data in the Processing Chain and Its Impact on the Error Induced by the Vicinity of the Coast.
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Talone, Marco, Camps, Adriano, Mourre, Baptiste, Sabia, Roberto, Vall-llossera, Mercè, Gourrion, Jérôme, Gabarró, Carolina, and Font, Jordi
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SOIL moisture ,SALINITY ,MICROWAVE imaging ,RADIOMETERS ,COASTS - Abstract
The Soil Moisture and Ocean Salinity (SMOS) Mission is the second of the European Space Agency's Living Planet Program Earth Explorer Opportunity Missions, and it is scheduled for launch in July 2009. Its objective is to provide global and frequent soil-moisture and sea-surface-salinity (SSS) maps, SMOS' single payload is the Microwave Imaging Radiometer by Aperture Synthesis (MIRAS) sensor, an L-band 2-D aperture-synthesis interferometric radiometer. For the SSS, the output products of SMOS, at Level 3, will have global coverage and an accuracy of 0.1-0.4 psu (practical salinity units) over 100 x 100-200 x 200 km² in 10-30 days. During the last few years, several studies have pointed out the necessity of combining auxiliary data with the MIRAS-measured brightness temperature to provide the required accuracy. In this paper, we propose and test two techniques to include auxiliary data in the SMOS SSS retrieval algorithm. Aiming at this, pseudo-SMOS Level-3 products have been generated according to the following steps: 1) A North Atlantic configuration of the NEMO-OPA ocean model has been run to provide consistent geophysical parameters; 2) the SMOS end-to-end processor simulator has been used to compute the brightness temperatures as measured by the MIRAS; 3) the SMOS Level-2 processor simulator has been applied to retrieve SSS values for each point and overpass; and 4) Level-2 data have been temporally and spatially averaged to synthesize Level-3 products. In order to assess the impact of the proximity to the coast at Level 3, and the effect of these techniques on it, two different zones have been simulated: the first one in open ocean and the second one in a coastal region, near the Canary Islands (Spain) where SMOS and Aquarius CAL/VAL activities are foreseen. Performance exhibits a clear improvement at Level 2 using the techniques proposed; at Level 3, a smaller effect has been recorded. Coastal proximity has been found to affect the retrieval of up to 150 and 300 km from the coast, at Levels 2 and 3, respectively. Results for both scenarios are presented and discussed. [ABSTRACT FROM AUTHOR]
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- 2009
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18. Toward an Optimal SMOS Ocean Salinity Inversion Algorithm.
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Gabarró, Carolina, Portabella, Marcos, Talone, Marco, and Font, Jordi
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- 2009
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19. Overview of the SMOS Sea Surface Salinity Prototype Processor.
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Zine, Sonia, Boutin, Jacqueline, Font, Jordi, Reul, Nicolas, Waldteufel, Philippe, Gabanó, Carolina, Tenerelli, Joseph, Petitcolin, Francois, Vergely, Jean-Luc, Talone, Marco, and Deiwart, Steven
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INTERFEROMETERS ,OPTICAL instruments ,REMOTE sensing ,ARTIFICIAL satellites ,MICROWAVE remote sensing ,SOIL moisture measurement ,OCEANOGRAPHY ,SALINITY - Abstract
The L-band interferometric radiometer onboard the Soil Moisture and Ocean Salinity mission will measure polarized brightness temperatures (Tb). The measurements are affected by strong radiometric noise. However, during a satellite overpass, numerous measurements are acquired at various incidence angles at the same location on the Earth's surface. The sea surface salinity (SSS) retrieval algorithm implemented in the Level 2 Salinity Prototype Processor (L2SPP) is based on an iterative inversion method that minimizes the differences between Tb measured at different incidence angles and Tb simulated by a full forward model. The iterative method is initialized with a first-guess surface salinity that is iteratively modified until an optimal fit between the forward model and the measurements is obtained. The forward model takes into account atmospheric emission and absorption, ionospheric effects (Faraday rotation), scattering of celestial radiation by the rough ocean surface, and rough sea surface emission as approximated by one of three models. Potential degradation of the retrieval results is indicated through a flagging strategy. We present results of tests of the L2SPP involving horizontally uniform scenes with no disturbing factors (such as sun glint or land proximity) other than wind-induced surface roughness. Regardless of the roughness model used, the error on the retrieved SSS depends on the location within the swath and ranges from 0.5 psu at the center of the swath to 1.7 psu at the edge, at 35 psu and 15 °C. Dual-polarization (DP) mode provides a better correction for wind-speed (WS) biases than pseudofirst Stokes mode (ST1). For a WS bias of -1 m . s
-1 , the corresponding SSS bias at the center of the swath is equal to -0.3 psu in DP mode and to -0.5 psu in ST1 mode. The inversion methodology implicitly assumes that WS errors follow a Gaussian distribution, even though these errors should follow more closely a Rayleigh distribution. [ABSTRACT FROM AUTHOR]- Published
- 2008
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20. Soil Moisture Retrieval from Space: The Soil Moisture and Ocean Salinity (SMOS) Mission.
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Kerr, Yann H., Waldteufel, Philippe, Wigneron, Jean-Pierre, Martinuzzi, Jean-Michel, Font, Jordi, and Berger, Michael
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SOIL moisture ,SALINITY - Abstract
Presents information on a study which described the antenna synthesis methods for Soil Moisture and Ocean Salinity mission. Mission description; Data acquisition and processing; Calibration and validation; Conclusion.
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- 2001
- Full Text
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21. Determination of sea surface salinity and wind speed by L-band microwave radiometry from a fixed platform
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Gabarró Prats, Carolina, Vall-Llossera Ferran, Mercedes Magdalena|||0000-0003-1357-7098, Font, Jordi, Camps Carmona, Adriano José|||0000-0002-9514-4992, Universitat Politècnica de Catalunya. Departament de Teoria del Senyal i Comunicacions, and Universitat Politècnica de Catalunya. RSLAB - Grup de Recerca en Teledetecció
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Salinity ,Astrophysics::Instrumentation and Methods for Astrophysics ,Teoria del senyal (Telecomunicació) ,Radiació--Mesurament ,Signal theory (Telecommunication) ,Radiometry ,Oceanography ,Physics::Atmospheric and Oceanic Physics ,Physics::Geophysics - Abstract
The European Space Agency Soil Moisture and Ocean Salinity (SMOS) mission aims at obtaining global maps of soil moisture and sea surface salinity from space for large-scale and climatic studies. It uses an L-band (1400–1427 MHz) Microwave Interferometric Radiometer by Aperture Synthesis to measure brightness temperature of the earth’s surface at horizontal and vertical polarizations ( h and v). These two parameters will be used together to retrieve the geophysical parameters. The retrieval of salinity is a complex process that requires the knowledge of other environmental information and an accurate processing of the radiometer measurements. Here, we present recent results obtained from several studies and field experiments that were part of the SMOS mission, and highlight the issues still to be solved.
22. Recovery of North-East Atlantic temperature fields from profiling floats: Determination of the optimal float number from sampling and instrumental error analysis
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Ruiz, Simón, Gomis, Damià, and Font, Jordi
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SALINITY , *TEMPERATURE , *ERROR analysis in mathematics - Abstract
Abstract: Argo is an international project that is deploying an array of temperature and salinity profiling floats over the global ocean. Here we use the error formulation derived from Optimal Statistical Interpolation to estimate statistical errors associated with the recovery of the temperature field in the North-East Atlantic ocean. Results indicate that with the present distribution of floats (119 in the considered domain), scales of wavelength larger than 500 km can be recovered with a relative uncertainty (rms error relative to the standard deviation of the field) of about 7% at 50 m, 8% at 200 m and 10% at 1000 m. This corresponds to mean absolute errors of 0.111 °C at 50 m, 0.104 °C at 200 m and 0.073 °C at 1000 m. The splitting of total errors into instrumental and sampling contributions reveals that, in the present scenario, errors are more due to the small number of floats than to instrumental errors, especially at upper levels. For scales larger than 500 km this will hold true until 200–250 floats are deployed (less than 200 for deep levels). In such a simulated scenario, the number of observations and the technology become approximately equally limiting factors for the accuracy of the temperature field mapping, with total relative errors of less than 2% at upper levels and about 3% at 1000 m. [Copyright &y& Elsevier]
- Published
- 2007
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23. Linear and non-linear T–S models for the eastern North Atlantic from Argo data: Role of surface salinity observations
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Ballabrera-Poy, Joaquim, Mourre, Baptiste, Garcia-Ladona, Emilio, Turiel, Antonio, and Font, Jordi
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LINEAR statistical models , *NONLINEAR statistical models , *SALINITY , *OCEAN temperature , *DATA analysis , *REGRESSION analysis , *ARTIFICIAL neural networks ,REMOTE sensing in oceanography - Abstract
Abstract: Linear and non-linear empirical models for salinity (S) are estimated from the Argo temperature (T) and salinity (delayed) data. This study focuses on the reconstruction of salinity in the upper 1200m of the eastern North Atlantic Ocean, a region characterized by the presence of many different water masses. While previous studies have found it necessary to split this region by boxes to fit different polynomial models in each box, a unique model valid for the entire region is fitted here. Argo profiles are randomly distributed on two sets: one for fitting the models and one for testing them. Non-linear regressions are built using neural networks with a single hidden layer and the fitting data set is further divided into two subsets: one for adjusting the coefficients (training data) and one for early stopping of the fitting (validation data). Our results indicate that linear regressions perform better than the climatologic T–S relationship, but that non-linear regressions perform better than the linear ones. Non-linear training using a three-data subsets strategy successfully prevents overfitting even when networks with 90 neurons in the hidden layer are being trained. While the presence of local minima may complicate the generalization of non-linear models to new data, network committees (created by training the same network from different random initial weights) are shown to better reproduce the test data. Several predictors are tested, and the results show that geographical, or surface, information does provide significant information. These results highlight the potential applications of future satellite missions measuring sea-surface salinity to reconstruct, when combined with temperature profiles, vertical salinity profiles. [Copyright &y& Elsevier]
- Published
- 2009
- Full Text
- View/download PDF
24. Surface salinity response to changes in the model parameters and forcings in a climatological simulation of the eastern North-Atlantic Ocean
- Author
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Mourre, Baptiste, Ballabrera-Poy, Joaquim, García-Ladona, Emilio, and Font, Jordi
- Subjects
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SALINITY , *CLIMATOLOGY , *ATMOSPHERIC temperature - Abstract
Abstract: The surface salinity response to changes of various external forcings and model parameters is investigated in a regional 1/3° configuration of the NEMO-OPA model implemented over the eastern North-Atlantic subtropical Ocean. Fourteen realistic climatological simulations are run. By default, neither relaxation to climatological surface salinity nor temperature is included. Forcing fields and parameters expected to impact the surface salinity are modified. These include: the wind stress, the surface temperature, wind speed and relative humidity entering the bulk calculation for sensible and latent heat fluxes, the precipitation, the data specified at open boundaries, the lateral viscosity operator, the salt lateral diffusivity, the vertical mixing scheme, the on/off switch of the double diffusion parameterization, the river runoffs and the SSS/SST restoring terms. The SSS standard deviation over this ensemble of model simulations is of the order of 0.1psu, which is also the order of the annual cycle of the surface salinity field in this area. In this experimental framework, the wind stress is found to have the largest impact on the model SSS, both in terms of mean field and annual variability. The sensitivity to the precipitation, atmospheric temperature, open boundary external data, and to the relaxation to climatological SSS and SST, is also significant. Of all the model parameterizations, the lateral salt diffusivity is the one associated to the strongest surface salinity model response. This work allows the identification of the main sources of error for model surface salinity. It paves the way for a more comprehensive investigation of SSS model error statistics, which is needed for future data assimilation experiments motivated by the close launch of the new SSS-observing SMOS and Aquarius satellite missions. [Copyright &y& Elsevier]
- Published
- 2008
- Full Text
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