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Sea Level Variability in the Strait of Gibraltar from Along-Track High Spatial Resolution Altimeter Products
Accurate coastal altimetry data are important for coastal observing systems (monitoring) and to re-analyze previous datasets. In this work, we analyzed the cross-strait variability in the eastern side of the Strait of Gibraltar using one descending track from the European Space Agency (ESA) Envisat RA-2 descending track #0360. We developed an accurate coastal altimetry product at high spatial resolution along track (∼350 m between two consecutive 18-Hz measurements). We focused on the analysis of the spatio-temporal variability of along-track Absolute Dynamic Topography (ADT) profiles. We first estimated the Sea Level Anomalies (SLA) using the Adaptive Leading Edge Subwaveform (ALES) retracker. To do this, an along-track Mean Sea Surface based on ALES data was computed by interpolating the along-track SSH profiles onto nominal tracks. Then, along-track ADTs were obtained using a local Mean Dynamic Topography (MDT) from a two-dimensional (depth-averaged), two-layer, finite-difference, hydrodynamic model (UCA2.5D). The cross-strait variability observed with the ADT profiles and its dependence with the wind regime was analyzed and discussed. Our preliminary results from the improved altimetry data sets confirm what was previously found in the area using only tide gauge data. The joint processing and exploitation approach can be applied to Sentinel-3A and future altimeter missions, and might be extended to other challenging coastal zones.
KeywordsCross-strait sea level variability Satellite altimetry Strait of Gibraltar Tide gauge
Special thanks are given to the Spanish Instituto Hidrográfico de la Marina (bathymetry dataset), Puertos del Estado (tide gauge data), and Agencia Estatal de Meteorología (in situ wind data).
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