10 research outputs found
Wind-induced variability in the Northern Current (northwestern Mediterranean Sea) as depicted by a multi-platform observing system
The variability and evolution of the Northern Current (NC) in the area off
Toulon is studied for 2 weeks in December 2011 using data from a glider, a
high-frequency (HF) radar network, vessel surveys, a weather station, and an atmospheric model.
The NC variability is dominated by a synoptic response to wind events, even
though the dataset also evidences early stages of transition from late summer
to fall–winter conditions. With weak winds, the current is mostly zonal and
in geostrophic balance even at the surface, with a zonal transport associated
with the NC of  ≈ 1 Sv. Strong westerly wind events (longer than
2–3 days) induce an interplay between the direct-wind-induced ageostrophic
response and the geostrophic component: upwelling is observed, with offshore
surface transport, surface cooling, flattening of the isopycnals, and reduced
zonal geostrophic transport (0.5–0.7 Sv). The sea surface response to wind
events, as observed by the HF radar, shows total currents rotated at  ≈ −55 to −90° to the right of the wind. Performing a
decomposition between geostrophic and ageostrophic components of the surface
currents, the wind-driven ageostrophic component is found to rotate by
 ≈ −25 to −30° to the right of the wind. The ageostrophic
component magnitude corresponds to  ≈ 2 % of the wind speed.</p
Assimilation of HF radar surface currents to optimize forcing in the northwestern Mediterranean Sea
HF radar measurements are used to optimize surface wind forcing and baroclinic open boundary condition forcing in order to constrain model coastal surface currents. This method is applied to a northwestern Mediterranean (NWM) regional primitive equation model configuration. A new radar data set, provided by two radars deployed in the Toulon area (France), is used. To our knowledge, this is the first time that radar measurements of the NWM Sea are assimilated into a circulation model. Special attention has been paid to the improvement of the model coastal current in terms of speed and position. The data assimilation method uses an ensemble Kalman smoother to optimize forcing in order to improve the model trajectory. Twin experiments are initially performed to evaluate the method skills. Real measurements are then fed into the circulation model and significant improvements to the modeled surface currents, when compared to observations, are obtained
Regional and coastal skill assessment of the SOCIB forecasting system at various time scales in the western Mediterranean Sea
Trabajo presentado en el 4th GODAE OceanView, celebrado en Lisboa, Portugal, del 31 de agosto al 4 de septiembre de septiembre de 2015Peer Reviewe
Toward an integrated HF radar network in the Mediterranean Sea to improve search and rescue and oil spill response: the TOSCA project experience
High-frequency (HF) coastal radars measure current velocity at the ocean surface with a 30-100 km range and 1-3 km resolution, every 0.25-1 h. HF radars are well suited to many applications, such as search and rescue (SaR), oil-spill mitigation and ecosystem management. Here we present a first organized core of 12 HF radars installed in five sites in four countries (Greece, Italy, France and Spain) within the European MED project, the Tracking Oil Spill and Coastal Awareness (TOSCA) network. Dedicated experiments tested radar capabilities to estimate transport driven by currents, which is the key feature for all the above applications. Experiments involved the deployment of drifters, i.e., floating buoys, acting as proxies for substances passively advected by currents. Using HF radars the search range is reduced by a factor of 1.6 to 5.3 after 24 h. The paper also underlines the importance of sharing common tools for HF radar data processing and the need to mitigate radio frequency interference. The effort can be regarded as an initial step toward the creation of a Mediterranean or European HF radar network, crucial for any European integrated ocean observing system (IOOS
Toward an integrated HF radar network in the Mediterranean Sea to improve search and rescue and oil spill response: the TOSCA project experience
International audienceHigh-frequency (HF) coastal radars measure current velocity at the ocean surface with a 30-100 km range and 1-3 km resolution, every 0.25-1 h. HF radars are well suited to many applications, such as search and rescue (SaR), oil-spill mitigation and ecosystem management. Here we present a first organized core of 12 HF radars installed in five sites in four countries (Greece, Italy, France and Spain) within the European MED project, the Tracking Oil Spill and Coastal Awareness (TOSCA) network. Dedicated experiments tested radar capabilities to estimate transport driven by currents, which is the key feature for all the above applications. Experiments involved the deployment of drifters, i.e., floating buoys, acting as proxies for substances passively advected by currents. Using HF radars the search range is reduced by a factor of 1.6 to 5.3 after 24 h. The paper also underlines the importance of sharing common tools for HF radar data processing and the need to mitigate radio frequency interference. The effort can be regarded as an initial step toward the creation of a Mediterranean or European HF radar network, crucial for any European integrated ocean observing system (IOOS)