Coastal circulation in the Gulf of Cádiz using multi-mission altimetry data
Event: 2022 Ocean Surface Topography Science Team Meeting
Session: Coastal Altimetry
Presentation type: Type Oral
Understanding and monitoring coastal currents and sea-level variability play a key role in the management of coastal areas and activities of high socio-economic and environmental impact developed in the coastal fringe, all of them affected by the current climate change scenario. In this context, one of the main challenges of coastal altimetry is to achieve observations of the sea surface close to land. In coastal zones, altimetry signals are affected by the presence of land within the footprint of the instrument. Besides, derived oceanographic parameters, such as surface current velocities, are partially controlled by local agents, as small-scale wind variability and abrupt bathymetry. The former issue is partially solved by advances in new retracking processing, which allow obtaining accurate measurements up to 3 km from land. The second point must be addressed by the development of local corrections. In this work, surface geostrophic current velocities derived from CryoSat-2 and Sentinel-3A/B altimetry data have been successfully corrected with a wind correction derived from a high-resolution wind speed data from the Weather Research and Forecasting model (WRF). The total surface currents have been used to study the coastal circulation of the Gulf of Cádiz (southwestern Iberian Peninsula), from January to December, 2020. Total surface velocities were previously validated with high-frequency (HF) radar in the study area, obtaining solid statistical scores (correlations up to 0.95 and root mean square errors lower than 10 cm/s), up to 3 km from the coastline. The results and methodology presented state the need of understanding local agents for exploiting altimetric data for coastal oceanographic purposes. Besides, it shows the possibilities of using altimetric data in any coastal location where no other observing systems are available.