Monitoring the Algerian Basin through Glider Observations, Satellite Altimetry and Numerical Simulations during the ABACUS Project

Autor: Aulicino, Giuseppe, Cotroneo, Yuri, Ruiz, Simón, Pascual, Ananda, Sánchez-Román, Antonio, Fusco, Giannetta, Torner, Marc Tòmas, Budillon, Giorgio, Tintoré, Joaquín
Rok vydání: 2019
Zdroj: Digital.CSIC. Repositorio Institucional del CSIC
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Popis: Poster presented at the World Ocean Circulation User Consultation meeting, on 21-22th February, 2019, in Frascati (Rome), Italy.
The Algerian Basin is a key component of the general circulation in the Western Mediterranean Sea. The presence of both fresh Atlantic water and more saline Mediterranean water gives the basin an intense inflow/ outflow regime and complex circulation patterns. Energetic mesoscale structures that evolve from meanders of the Algerian Current into isolated cyclonic and anticyclonic eddies dominate the area, with marked repercussions on biological activity. Despite its remarkable importance, this region and its variability are still poorly known and basin-wide knowledge of its meso- and submesoscale features is still incomplete. Studying such complex processes requires a synergistic approach that involves integrated observing systems. In recent years, several studies have demonstrated the advantages of combined use of autonomous underwater vehicles, such as gliders, with a new generation of satellite altimetry. In this context, we present the monitoring activities conducted in the Algerian Basin between September 2014 and May 2018, in the framework of several editions of the “Algerian BAsin Circulation Unmanned Survey - ABACUS” project. These activities were realized through the SOCIB (Balearic Islands Coastal Observing and Forecasting System) Glider Facility Open Access Programme and were supported by the Joint European Research Infrastructure network for Coastal Observatories (JERICO) Trans National Access (TNA), the SOCIB external access and the JERICO-NEXT TNA. During the ABACUS missions, a total of 12 glider transects were carried out between the island of Mallorca and the Algerian coast, collecting Temperature, Salinity, Turbidity, Oxygen and Chlorophyll concentration high resolution data in the first 975 m of the water column. In situ data collection was supported by near real time remotely sensed data from different platforms over the Western Mediterranean Sea. In particular, gridded altimetry data provided by the Archiving, Validation and Interpretation of Satellite Oceanographic data (AVISO), Sea Surface Temperature (SST) and Chlorophyll-a concentration (Chla) information from MODerate resolution Imaging Spectroradiometer (MODIS) data acquired by NASA were used to provide a large scale description of the dynamics and surface water masses. Glider surveys were always conducted along the groundtracks of operating altimetry satellites, i.e. SARAL/AltiKa and Sentinel-3, and were planned in order to get always the glider at sea during the satellites overflight. Furthermore, the adaptive sampling capabilities of the Slocum gliders also allowed to partially modify their tracks in order to investigate the oceanographic characteristics of interesting mesoscale structures identified through altimetry. Here we report on comparative analyses of glider measurements with both co-located (SARAL/AltiKa and Sentinel-3) altimetric products, and CMEMS numerical simulations. Results show similar patterns for glider-derived dynamic heights and altimetric absolute dynamic topography. Even though larger discrepancies are observed near the Balearic and Algerian coasts, correlation coefficients between glider and satellite observations seem mostly to be affected by synopticity between remote sensed and in situ measurements. We expect to apply this ocean observing strategy also for validating products provided by new generation altimeters that are designed to be better suited for coastal, mesoscale and submesoscale monitoring, such as the forthcoming wide-swath radar interferometer Surface Water and Ocean Topography (SWOT).
Databáze: OpenAIRE
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