Circulation in a stratified and wind-forced Gulf of Lions, NW Mediterranean Sea: In situ and modeling data

Abstract

ADCP, thermosalinograph, and meteorological data were collected during a short cruise (SARHYGOL 3; June 13-15, 2000) throughout the Gulf of Lions, NW Mediterranean Sea. The 3-D hydrodynamical model Symphonie reproduces well the circulation features observed in situ. The Northern Current (NC) - geostrophic current bordering the gulf along its continental slope - is well modeled with slight differences in its position. When the modeled stratification of the gulf is shallower than the measured stratification, the modeled NC is further offshore than the real NC (and reciprocally). The model allows the determination of the life-time and generating processes of the intrusions of the NC on the shelf. During the cruise, two different types of intrusions of the NC are found: (1) an intrusion at the eastern side of the gulf, that lasted 5 days and was due to a combination of the water column stratification and wind-forcing effects at the start of the continental shelf; (2) an intrusion at the center of the gulf, that lasted less than 12 h and was generated by the proximity of a positive and a negative wind stress curls. The coupled in situ data/model analysis also provides a better understanding on inertial oscillations. A strong inertial oscillation, with maximum amplitude of 60 cm/s, is clearly observed at the western side of the gulf due to the absence of the NC there. The model also exhibits this oscillation, and provides its temporal variations. The analysis, closely coupling in situ measurements and model results, provides information that would not have been obtained using either data separately. © 2004 Elsevier Ltd. All rights reserved.