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  • The 2013 Ibiza calibration campaign of Jason-2 and Saral altimeters

     Frappart, Frédéric; Roussel, Nicolas; Biancale, Richard; Martinez Benjamin, Juan Jose; Mercier, Flavien; Pérosanz, Felix; Gárate Pasquín, Jorge; Martin Davila, José; Pérez Gómez, Begoña; Gracia Gomez, Carlos; Lopez Bravo, Rogelio; Tapia Gomez, Ana Maria; Gili Ripoll, Jose Antonio; Hernandez Pajares, Manuel; Salazar, Mario; Bonnefond, Pascal; Valles Casanova, I. Berenguer
    Marine geodesy
    DOI: 10.1080/01490419.2015.1008711
    Date of publication: 2015-02-09
    Journal article

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    This study presents the results of the 2013 Ibiza (Western Mediterranean) calibration campaign of Jason-2 and SARAL altimeters. It took place from 14 to 16 September 2013 and was composed of two phases: the calibration of the GNSS (Global Navigation Satellite System) buoys to estimate the antenna height of each of them and absolute calibration to estimate the altimeter bias (i.e., the difference of sea level measured by radar altimetry and GNSS). The first one was achieved in the Ibiza harbor at a close vicinity of the Ibiza tide gauge and the second one was at ˜ 40 km at the northwest of Ibiza Island at a crossover point of Jason-2 and SARAL nominal groundtracks. Five buoys were used to delineate the crossover region and their measurements interpolated at the exact location of each overflight. The overflights occurred two consecutive days: 15 and 16 September 2013 for Jason-2 and SARAL respectively. The GNSS data were processed using precise point positioning technique. The biases found are of (-0.1 ± 0.9) and (-3.1 ± 1.5) cm for Jason-2 and SARAL respectively.

  • Absolute calibration of Jason-2 and Saral during the 2013 Ibiza calibration campaign

     Martinez Benjamin, Juan Jose; Frappart, Frédéric; Roussel, Nicolas; Biancale, Richard; Pérosanz, Felix; Gárate Pasquín, Jorge; Martin Davila, José; Pérez Gómez, Begoña; Gracia Gomez, Carlos; Lopez Bravo, Rogelio; Tapia Gomez, Ana Maria; Gili Ripoll, Jose Antonio; Gonzalez Gonzalez, Juan Carlos; Salazar Lino, Mário; Hernandez Pajares, Manuel; Sanz Conde, M. Mercedes; Valles Casanova, I. Berenguer
    Ocean Surface Topography Science Team Meeting
    p. 207
    Presentation's date: 2014-10
    Presentation of work at congresses

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    An altimetry calibration campaign was achieved in the Mediterranean Sea, close to the Ibiza island (Baleares) area, last September in the framework of a Spanish-French cooperation. Its goal was to provide absolute biases for the Jason-2 and AltiKa/Saral altimeters through comparisons with GNSS measurements on buoys. A similar Spanish/French experiment was already performed for Jason-1in June 2003 in this geographical area under the name IBIZA 2003 campaign. Direct absolute altimeter calibration, estimating the Jason-2 and AltiKa/Saral biases, was made from direct overflights using GPS buoys. This method does not require any modelling of geoid and tidal error. The crossover point between Jason-2 and Saral North of Ibiza (around 40 nm) and West of Mallorca island was found to be optimal for our purposes as it allows measurements at a one-day time-lag and a similar configuration of buoys for each satellite pass. 5 buoys were deployed near a Jason-2/AltiKA Saral crossover point to determine the sea surface in the along-track and cross-track directions, to estimate by interpolation the exact nadir point of the satellite. Here, we present the experimental settings of the campaign and the datasets used in this study, the methods used for comparing altimetry data with GNSS measurements, and the first results of the absolute calibration.

  • The 2013 Ibiza calibration campaign of Jason2 and Sara altimetersin the baleares area : preliminary results

     Martinez Benjamin, Juan Jose; Biancale, Richard; Frappart, Frédéric; Martin Davila, José; Gárate Pasquín, Jorge; Gili Ripoll, Jose Antonio; Roussel, Nicolas; Lopez Bravo, Rogelio; Tapia Gomez, Ana Maria; Gracia Gomez, Carlos; Gonzalez Gonzalez, Juan Carlos; Sanz Conde, M. Mercedes; Perez, Begoña; Valles Casanova, I. Berenguer
    Scientific Assembly of the Committee on Space Research
    p. 1-2
    Presentation's date: 2014-08
    Presentation of work at congresses

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    An altimetry calibration campaign was achieved in the Mediterranean Sea, close to the Ibiza is- land (Baleares) area, last September in the framework of a Spanish-French cooperation. Its goal was to provide absolute biases for the Jason-2 and AltiKa/Saral altimeters through comparisons with GNSS measurements on buoys. A similar Spanish/French experiment was already per- formed for Jason-1 in June 2003 in this geographical area under the name IBIZA 2003 campaign. A geometric precise levelling was made at the Marina de Botafoch (Ibiza) harbour. Direct ab- solute altimeter calibration, estimating the Jason-2 and AltiKa/Saral biases, was made from direct over ights using GPS buoys. This method does not require any modelling of geoid and tidal error. The Spanish/French Jason-2 and AltiKa/Saral calibration campaign IBIZA 2013 was carried out in June 14-16, 2013 in the area of Ibiza Island in the NW Mediterranean Sea. The experiment was composed of two phases: i) the pre-calibration of the 5 buoys by reference with the Ibiza tide gauge to level the GPS antennas above the sea level, and ii) the absolute calibration of the altimeters at the cross-over point. The crossover point between Jason-2 and Saral North of Ibiza (around 40 nm) and West of Mallorca island was found to be optimal for our purposes as it allows measurements at a one-day time-lag and a similar conguration of buoys for each satellite pass. Five buoys were deployed near a Jason-2/AltiKA Saral crossover point to determine the sea surface in the along-track and cross-track directions, to estimate by interpolation the exact nadir point of the satellite. Here, we present the experimental settings of the campaign and the datasets used in this study, the methods used for comparing altimetry data with GNSS measurements, and the rst results of the absolute calibration.

  • Preliminary results of the 2013 Ibiza calibration campaign of Jason 2 and Saral altimeters

     Frappart, Frédéric; Martinez Benjamin, Juan Jose; Gracia Gomez, Carlos; Lopez Bravo, Rogelio; Tapia Gomez, Ana Maria; Valles Casanova, I. Berenguer; Gili Ripoll, Jose Antonio
    IEEE International Geoscience and Remote Sensing Symposium
    p. 4473-4476
    DOI: 10.1109/IGARSS.2014.6947485
    Presentation's date: 2014-07
    Presentation of work at congresses

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    This study presents the preliminary results of the 2013 Ibiza calibration campaign of Jason-2 and Saral altimeters. It took place from 14 to 16 September 2013 and was composed of two phases: the calibration of the GNSS buoys to estimate the antenna height of each of them and absolute calibration to estimate the altimeter bias (i.e., the difference of sea level measured by radar altimetry and GNSS). The first one was achieved in the Ibiza harbor at a close vicinity of the Ibiza tide gauge and the second one was at ~ 40 km at the northwest of Ibiza Island at a crossover point of Jason-2 and Saral nominal groundtracks. Five buoys were used to delineate the crossover region and their measurements interpolated at the exact location of each overflight. The overflights occurred two consecutive days: 15 and 16 September 2013 for Jason-2 and Saral respectively. Absolute biases of 0.1 and -4 cm were found for Jason-2 and Saral respectively.

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    The Baleares 2013 Calibration Campaign of Jason-2 and Saral Altimeters  Open access

     Martinez Benjamin, Juan Jose; Frappart, Frédéric; Roussel, Nicolas; Biancale, Richard; Gárate Pasquín, Jorge; Martin Davila, José; Perez, Begoña; Gracia Gomez, Carlos; Lopez Bravo, Rogelio; Tapia Gomez, Ana Maria; Gili Ripoll, Jose Antonio; Gonzalez Gonzalez, Juan Carlos; Hernandez Pajares, Manuel; Salazar Lino, Mário
    International GNSS Service Workshop
    p. 1
    Presentation's date: 2014
    Presentation of work at congresses

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    The 2013 Balearic campaign GNSS position analysis of the 2013 will be performed with different softwares by different groups (similarly as it is being done in the International GNSS Service for their different products), in order improve the high demanded accuracy for JASON2 and SARAL altimeters precise calibration. In particular JPL GIPSY-OASIS software will be used, with the undifferenced PPP ambiguity fixing strategy. In order to improve the results accuracy, two similar networks are being processed. The first network includes the deployed GNSS receivers and the reference stations. The second one is a control network, defined by using the permanent receivers in the California dense network with a similar distribution as the main altimeter campaign network. In this case, the position of the receivers plying the role of buoys are being processed in the same kinematic way than the actual buoys, in order to compare them with the very accurate positions obtained with GIPSY-OASIS static processing.

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    Geodetic infrastructure in the Ibiza and Barcelona harbours for sea level monitoring  Open access

     Martinez Benjamin, Juan Jose; Gili Ripoll, Jose Antonio; Lopez Bravo, Rogelio; Tapia Gomez, Ana Maria; Pérez Gómez, Begoña; Gracia Gomez, Carlos; Pros Llavador, Francesc; Palau Teixidó, Vicenç
    American Geophysical Union Fall Meeting
    p. 1
    Presentation's date: 2013-12
    Presentation of work at congresses

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    The presentation is directed to the description of the actual situation and relevant information of the geodetic infrastructure of Ibiza and Barcelona sites for sea level determination and contribution to regional sea level rise. Time series are being analysed for mean sea level variations www.puertos.es. .In the framework of a Spanish Space Project, the instrumentation of sea level measurements has been improved by providing the Barcelona site with a radar tide gauge Datamar 2000C from Geonica s.l. near an acoustic tide gauge. Puertos del Estado installed in 2007 a MIROS radar tide gauge and the Barcelona Harbour Authority a GPS referente station in the roof of the new Control Tower situated in the Energy Pier. The radar sensor is over the water surface, on a L-shaped structure which elevates it a few meters above the quay shelf. 1-min data are transmitted to the ENAGAS Control Center by cable and then sent each 1 min to Puertos del Estado by e-mail. There is a GPS station Leica Geosystems GRX1200 GG Pro and antenna 1202. Precision levelling has been made several times in the last two years because the tower is founded in reclaimed land. The measured settlement rate is about 1cm/year that may be could mask the values registered by the tide gauge. A description of the actual infrastructure at Ibiza harbour at Marina de Botafoch, is presented and its applications to sea level monitoring and altimeter calibration in support of the main CGPS at Ibiza harbour. It is described the geometrical precision levelling made in June 2013 between the radar tide gauge and the GPS station. In particular, the CGPS located at Ibiza harbour is essential for its application to the marine campaign Baleares 2013, near Ibiza island. The main objective is to determine the altimeter bias for Jason-2, about 9:09 UTC September 15, 2013, and Saral/AltiKa, about 05:30 UTC September 16, UTC. These activities has been received funding of the Ministerio de Ciencia e Innovacion under Spanish National Project CGL2009-13435/CLI.

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    Baleares 2013 Calibration Campaign for Jason-2 and Saral/AltiKa  Open access

     Martinez Benjamin, Juan Jose; Biancale, Richard; Martin Davila, José; Gárate Pasquín, Jorge; Pérez Gómez, Begoña; Gili Ripoll, Jose Antonio; Lopez Bravo, Rogelio; Tapia Gomez, Ana Maria; Gracia Gomez, Carlos; Frappart, Frédéric; Roussel, Nicolas
    Ocean Surface Topography Science Team Meeting
    p. 1
    Presentation's date: 2013-10
    Presentation of work at congresses

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    A Baleares calibration campaign in Spanish-French cooperation is being prepared for mid September 2013 for the altimeters of Jason-2 and Saral/AltiKa in the Ibiza island area. A similar Spanish/French experience with Jason-1 was made in June 2003 in this geographical area under IBIZA 2003 campaign. In this local/regional campaign focusing in bias, we foresee to calibrate the altimeter of Jason-2 and Saral satellites by means of GPS buoys. 4 buoys will be used near a node from Jason-2 (September 15 about 9:38 in ascending track) and Saral (September 15 about 7:30 in ascending track) satellites to get the slope of the sea in along track and cross track directions, what is necessary to interpolate the exact nadir point of the satellite. It will be used Argos floating transmitters from CLS to be tied to the buoys with a long rope. We have thought over different configurations. The crossover point between Jason-2 and Saral North of Ibiza (around 40 nm) and West of Mallorca island seems to be optimal in order to have a comparable layout of buoys at the same place for both satellites, of couse at one day interval. This would allow moreover cross calibration between Jason2 and Saral. The GPS receivers will be at 1Hz. It will be used the CGPS at Ibiza harbour from Puertos del Estado. A description of the actual geodetic infrastructure of Ibiza site will be presented. This campaign Baleares 2013 is founded from the Ministerio de Ciencia e Innovacion of Spain under National Project I+D+i ref:CGL2009-13435/CLI.

  • Implementation of marine altimeter calibration campaign in the area of Ibiza island

     Martinez Benjamin, Juan Jose; Lopez Bravo, Rogelio; Pérez Gómez, Begoña; Gili Ripoll, Jose Antonio; Tapia Gomez, Ana Maria; Gonzalez Gonzalez, Juan Carlos; Sanz Conde, M. Mercedes; Gracia Gomez, Carlos
    European Space Agency Living Planet Symposium
    p. 1-4
    Presentation's date: 2013
    Presentation of work at congresses

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    The presentation is directed mainly to the description of the actual situation of the Ibiza site in preparation for a new altimeter calibration marine campaign of Jason-2 and Sara/AltiKa satellites to be made in september 2013. A description of the two geometric levelling campaigns made in June and September 2013 is included