Eddy properties in the Western Mediterranean Sea from satellite altimetry and a numerical simulation

Abstract

Three different eddy detection and tracking methods are applied to the outputs of a high‐resolution simulation in the Western Mediterranean Sea in order to extract mesoscale eddy characteristics. The results are compared with the same eddy statistics derived from satellite altimetry maps over the same period. Eddy radii are around 30 km in altimetry maps whereas, in the model, they are around 20 km. This is probably due to the inability of altimetry maps to resolve the smaller mesoscale in the region. About 30 eddies are detected per day in the basin with a very heterogeneous spatial distribution and relatively short lifespans (median life around 13 days). Unlike other areas of the open ocean, they do not have a preferred direction of propagation but appear to be advected by mean currents. The number of detected eddies seems to present an annual cycle when separated according to their lifespan. With the numerical simulation, we show that anticyclones extend deeper in the water column and have a more conic shape than cyclones.

High‐Resolution Observations and Tracking of a Dual‐Core Anticyclonic Eddy in the Algerian Basin

“…The characteristic contour of the eddy (blue line in Figure 2f) is in good agreement with the standard SST pattern of anticyclonic eddies in winter, showing a warm SST anomaly (Puillat et al, 2002). At that time, the AE had moved back to the Algerian coast following a cyclonic path in accordance with a two-gyre circulation of the eddies depicted by Testor et al (2005) and Escudier, Renault, et al (2016). This eddy remained coherent (it kept an anticyclonic core with closed streamlines) and interacted with the Algerian Current inducing a very large meander along the coast that propagate eastward (Figure 2e).…”

“…A deep cyclonic circulation within the Algerian Basin has been demonstrated using RAFOS drifters, and two subsurface gyres were identified, centered at around 37°30′N to 2°30′E and 38°30′N to 6°00′E (Testor et al, ). Revisiting 20 years of altimetric data with several eddy detection algorithms, Escudier, Renault, et al () confirmed the two counterclockwise circulations of the eddies in the Algerian Basin and identified two preferential areas of detachment from the Algerian Current within the intervals of 2–4°E and 6–8°E. The dynamics of the Algerian Basin are dominated by numerous anticyclonic eddies, filaments, and meandering.…”

Zooplankton community response to the winter 2013 deep convection process in the NWMediterranean Sea

“…Journal of Geophysical Research: Oceans 10.1002/2016JC012176 was a significant scatter in these relationships indicating the potential impact of patchiness and/or undersampling by the UVP. Although mesoscale features are well identified in the central NWMS [Escudier et al, 2016], and do impact zooplankton [Pinca and Dallot, 1997;Alcaraz et al, 2007;Carlotti et al, 2014], only one eddy was identified during L2 along the Balearic Front but this feature was not sampled.…”

Temporal and Spatial Hydrodynamic Variability in the Mallorca Channel (Western Mediterranean Sea) From 8 Years of Underwater Glider Data

“…Eddies with different sizes are common dynamical features of the Balearic circulation. They are formed locally or advected by the NC (e.g., Pascual et al, 2002;Bouffard et al, 2012;Amores et al, 2013;Mason & Pascual, 2013;Bosse et al, 2016;Escudier, Renault, et al, 2016). The exchange of water masses through the island channels has been shown to have an impact on the development of mesoscale eddies within the Balearic subbasin (Pascual et al, 2002;Amores et al, 2013).…”