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Data from the altimeter onboard the European Remote Sensing Satellite (ERS1) was used to study the circulation of the Alboran Sea between -6 to 0 degrees and 35 to 38 degrees North. The results indicate that combining sea surface temperature data and sea level data from altimetry hold promise for understanding the circulation of the Western Mediterranean.

Since many years, space borne radar altimeters have brought a powerful contribution in monitoring the dynamic sea surface topography, and in understanding better the ocean circulation and its impact on the earth system. Today, altimetric satellites are observing the whole oceans, measuring the sea surface height with a rms precision of 3-4 cm at 1 Hz sampling, as demonstrated by TOPEX/POSEIDON, launched in 1992, by Jason-1, launched in 2001 and by ENVISAT, launched in 2002. Such a high level error budget was achieved thanks to the tremendous improvements which have been obtained in radar performances as well as in precise orbit determination. Indeed, applications of altimetry in oceanography and geodesy requires very precise measurements of the satellite-sea level range, along with appropriate environmental corrections, but also an accurate knowledge of the satellite position with respect to the Earth reference. One campaign has also been made in June 2003 at the Ibiza island area (Martinez-Benjamin et al., 2003). The marine geoid has been used to relate the coastal tide gauge data from Ibiza and San Antonio harbours to off-shore altimetric data. A technical Spanish contribution to the calibration experience has been the design of GPS buoys and GPS catamaran taking in account the University of Colorado at Boulder and Senetosa/Capraia designs. We present a synthesis of the sea level results results obtained from the altimeter calibration campaign at Ibiza island on June 2003 using the direct measurements from GPS buoys and the derived marine geoid. The main objective of the marine campaign was to check the value of Ibiza Island as a permanent calibration site in the western Mediterranean Sea, to complement the Corsica site in the network of altimeter calibration sites.

One airborne calibration campaign with a Partenavia P-68 (ICC) carrying an Optech Lidar ALTM-3025 (ICC) was made on June 16, 2007, overflying l'Estartit harbour (about 6 km wide by 50 km long) and mapping with observe lidar strips of about 800 m. wide. The validation of this new technology LIDAR may be useful to fill coastal areas where satellite radar altimeters are not measuring due to the large footprint and the resulting gaps of about 20-40 km within the coastline. Measurements with a GPS Buoy were made during the experience and a GPS reference station was installed in Aiguablava. A DSM of l'Estartit harbour area was derived in the first results from the campaign.

Sea level is an environmental variable which is widely recognised as being important in many scientific disciplines as a control parameter for coastal dynamical processes or climate processes in the coupled atmosphere-ocean systems, as well as engineering applications. A major source of sea-level data are the national networks of coastal tide gauges, in Spain belonging to different institutions as the Instituto Geografico Nacional (IGN), Puertos del Estado (PE), Instituto Hidrografico de la Marina (IHM), etc. Three Spanish sites for monitoring sea level are located in Ibiza island, l'Estartit and Barcelona. L'Estartit tide gauge is a classical floating tide gauge set up in l'Estartit harbour (NE Spain) in 1990. Data are taken in graphics registers from which each two hours the mean value is recorded in an electronic support and delivered to the Permanent Service for Mean Sea level (PSMSL). Periodic surveying campaigns along the year are carried out for monitoring possible vertical movement of the geodetic benchmark adjacent to the tide gauge. 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 and with a continuous GPS station nearby. The radar tide gauge is a Datamar 3000C device and a Thales Navigation Internet- Enabled GPS Continuous Geodetic Reference Station (iCGRS) with a choke ring antenna. It is intended that the overall system will constitute a CGPS Station of the ESEAS (European Sea Level) and TIGA (GPS Tide Gauge Benchmark Monitoring) networks. Puertos del Estado (Spanish Harbours) installed the tide gauge station at Ibiza harbour in lanuary 2003. The station belongs to the REDMAR network, composed at this moment by 21 stations distributed along the whole Spanish waters, including also the Canary islands (http://www.puertos.es). The tide gauge also belongs to the ESEAS (European Sea Level) network. Also it has a radar tide gauge at Barcelona harbour.A description of the actual infrastructure at Ibiza, l'Estartit and Barcelona is presented and its applications to sea level monitoring and altimeter calibration in support of the main CGPS at Ibiza harbour. Three Begur Cape experiences on radar altimeter calibration and marine geoid mapping were made on 1999, 2000 and 2002. One campaign was also made in lune 2003 at the Ibiza island area. GPS buoys and GPS catamaran were used. We present a synthesis of the sea level results results obtained from TOPEX/POSEIDON and JASON-1 altimeter calibration campaigns using the direct measurements from GPS buoys and the derived marine geoid. The main objective of the marine campaigns is to check the value of Ibiza Island as a permanent calibration site in the western Mediterranean Sea, to complement the Corsica site in the network of altimeter calibration sites.Now there is preparation for a new Ibiza/Cape of Begur altimeter calibration campaign after launch of JASON-2 at the Vanderbergh site scheduled on lune 20, 2008.

Martínez Benjamín, J. J. et al., Within the framework of a project comprising part of the Spanish Space Program related to the JASON-1 CNES (Centre National d'Etudes Spatiales)/ NASA (National Aeronautics and Space Administration) mission, a campaign was conducted from June 9-17, 2003, on the Absolute Calibration Site of the island of Ibiza. The objective was to determine the local marine geoid slope under the ascending (187) and descending (248) Jason-1 ground tracks, in order to allow a better extrapolation of the open-ocean altimetric data with on-shore tide gauge locations, and thereby improve the overall precision of the calibration process. For this we have used a catamaran with two GPS antennas onboard, following the Corsica/Senetosa design (Bonnefond et al. 2003a). Five GPS reference stations were deployed in order to reduce the distance between the areas covered by the catamaran and the fixed GPS receiver used in the kinematic process. The geodetic activities (e.g., GPS, leveling) have enabled the building of a very accurate (few mm) network in a reference frame compatible with the satellite altimetry missions (ITRF 2000). The GPS kinematic data were processed using two different software programmes, allowing checking of the consistency of the solutions. If the standard deviation of the differences (3.3 cm) is close to the kinematic process precision, they exhibit some large values (up to 14 cm). These large discrepancies have been reduced using a weighting based on the crossover differences. Inasmuch as the distances between the tide gauges and the areas covered by the GPS catamaran were becoming large, we have used the MOG2D ocean model (Carrère and Lyard 2003) to correct the sea surface from tides. In the farthest areas, the crossover differences show an improvement by a factor of two. Finally, we also present preliminary results on Jason-1 altimeter calibration using the derived marine geoid. From this analysis, the altimeter bias is estimated to be 120 ± 5 mm. The quality of this first result validates the whole GPS-based marine geoid processing, for which the accuracy is estimated to be better than 3 cm rms at crossovers. Copyright © Taylor & Francis Inc.

Esta Tesis Doctoral se centra sobre el análisis de los importantes cambios que se están produciendo en el entorno de la distribución comercial dentro del sector turístico, abordándolo directamente desde la óptica de las empresas hoteleras y bajo un enfoque de marketing. El objetivo genérico que se persigue es estudiar si las estrategias de distribución, basadas en los sistemas verticales de marketing u otras formas de cooperación e integración empresarial, que parece estar constituyendo una alternativa positiva en buena parte de los sectores de bienes tangibles, pueden suponer también para las pequeñas y medianas empresas hoteleras una vía para mejorar su competitividad ante los fuertes procesos de globalización que se están produciendo en esta industria. Así y tras un profundo análisis del sistema de distribución en la industria turística, de las repercusiones de las nuevas tecnologías de la información y las comunicaciones sobre la comercialización de las empresas de este sector, y las distintas tendencias en cuanto a los procesos de integración y cooperación de empreas dentro de esta industria, se procede, a través de un análisis empírico a investigar la significaión de todos estos aspectos en el caso del sector hotelero de la Comunidad Autónoma Andaluza, realizando para ello una encuesta dirigida al colectivo de establecimiento hoteleros ubicados en la geografía andaluza. Partiendo del análisis estadístico de los datos recogidos en dicha investigación, se plantean numerosas conclusiones y recomendaciones de cara a la mejora de la competitividad de las pequeñas y medianas empresas hoteleras entre los importantes procesos de globalización, concentración e incremento de la competencia dentro del sector turístico.

Due to the increased covering from satellites it is possible to find several sensors offering spatial information of the oceanic surface features as images obtained through different sensors such as visible, intensity, color infrared or microwaves (S.A.R.) (from satellites such as METEOSAT, NOAA, TOPEX, LANDSAT, ERS1 and ERS2). We use data from the altimeter and the SAR images from the ERS-1 as well as images from ERS- 2. SAR images and their analysis with flow visualization techniques uses correlations from SAR intensity that allow the calculation of maps of the spatial variation of integral scales. The integral scales which seem dominant, range between 15 and 20 Km showing a limit at the Rossby deformation radius. These larger lengths may be explained as micro and mesoscale vortex interaction in the surface of the ocean. They might also be related to barometric corrections caused by the mirror images produced by the atmospheric pressure on the atmosphere, but checking the weather maps at the same time confirms that atmospheric relevant lengthscales are much larger as a consequence of the larger Rossby deformation radius for atmospheric flows.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A coupling of field and satellite remote sensing data were used to improve the knowledge with respect to coastal dynamics and erosion process as well as on the importance of mangroves as a mechanism of fertilization of tropical NE-Brazilian waters. RADARSAT and ERS SAR images were used to position morphologic features, to trace coastline evolution and detect changes in mangrove coverage. Analysis of aerial photography, ERS and RADARSAT images, reveal that mangrove areas have been drastically reduced in the last decades, to give places to new urban settling. Coastal erosion appears to have been intensified after the installation of harbor facilities and by the construction of beach houses and other structures along the shore, that modify coastal circulation and nearshore sediment transport. Particular importance is given to the analysis of the RADARSAT SAR image taken in September 1997.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

We consider the determination of the potential from the orbit of a satellite. The potential obtained is not unique because the satellite might describe the same orbit with different forces. The classical problem of determination of orbits has a unique solution, for given initial conditions. The problem is reduced to the planar case with a conservative force. The mathematical results depend on the arbitrary functions of the system of coordinates used.