SOCIB HF radar, a key contribution to multi-platform ocean observation

The Balearic Islands Coastal Observing and Forecasting System (SOCIB) is a multi-platform, distributed and integrated system located in the North Western Mediterranean sea that responds to science and society needs. The High-Frequency radar (HFR) facility is based on two 13.5 MHz Coastal Ocean Dynamics Applications Radar (CODAR) SeaSonde system monitoring the surface circulation in the Ibiza Channel (IC). It provides in real-time hourly state of the art quality controlled surface velocity observations since June 2012. The accuracy of velocities have been investigated using a comprehensive data set based on current-meter and surface drifters. Good agreements with previous studies are obtained. The circulation patterns and their variability in the IC have been investigated based on a multi-platform analysis combining HFR with Gliders, SARAL/AltiKa satellite altimeter, ADCP/current meter and wind. Surface currents clearly show signatures of Atlantic water inflow (respectively Northern Current outflow) in the eastern (respectively western) part of the IC. The surface current is highly variable with no prevailing direction of variability. More than 60% of the surface current variability is explained by wind, with significant presence of inertial motion. Wind breezes and tide induced surface currents have also important spectral signatures. Good agreement between HFR and geostrophic current is found under low wind conditions. These preliminary results underline the oceanic circulation complexity in the IC. HFR velocities are used to validate the SOCIB Western Mediterranean Operational forecasting system (WMOP) simulation, with the aim to implement in the near future operational data assimilation methodologies based on HFR velocities and other available observations. Some initial results will be shown concerning the comparison performed between the model surface currents and the HFR observations.