The seasonal cycle of the Atlantic Jet dynamics in the Alboran Sea: direct atmospheric forcing versus Mediterranean thermohaline circulation

TThe Atlantic Jet (AJ) is the inflow of Atlantic sur- face waters into the Mediterranean Sea. This geostrophically adjusted jet fluctuates in a wide range of temporal scales from tidal to subinertial, seasonal, and interannual modifying its velocity and direction within the Alboran Sea. At seasonal scale, a clearly defined cycle has been previously described, with the jet being stronger and flowing towards the northeast during the first half of the year and weakening and flowing more southwardly towards the end of the year. Different hy- pothesis have been proposed to explain this fluctuation pattern but, up to now, no quantitative assessment of the importance of the different forcings for this seasonality has been provided. Here, we use a 3D hydrodynamic model of the entire Medi- terranean Sea forced at the surface with realistic atmospheric conditions to study and quantify the importance of the differ- ent meteorological forcings on the velocity and direction of the AJ at seasonal time scale. We find that the direct effects of local zonal wind variations are much more important to ex- plain extreme collapse events when the jet dramatically veers southward than to the seasonal cycle itself while sea level pressure variations over the Mediterranean seem to have very little direct effect on the AJ behavior at monthly and longer time scales. Further model results indicate that the annual cycle of the thermohaline circulation is the main driver of the seasonality of the AJ dynamics in the model simulations.

MACIAS MOY Diego;  GARCIA GORRIZ Elisa;  STIPS Adolf; 

2016-02-18

SPRINGER HEIDELBERG

JRC91588

1616-7341,   

http://link.springer.com/article/10.1007%2Fs10236-015-0914-y,    https://publications.jrc.ec.europa.eu/repository/handle/JRC91588,   

10.1007/s10236-015-0914-y,