Deep water mass circulation in the Alboran Basin: Measurements - August to November'83: ALBORAN III

Abstract

The circulation of the deep water mass in the western Alboran Sea is studied. Interaction between the

three different water masses, the Atlantic, the Levantine and the Deep Western Mediterranean water,

causes complicated flow patterns. Floats and current meters deployed in the northern and the central western Alboran displayed slow and variable current speed. Floats deployed on the Moroccan

continental slope moved swiftly along the slope towards Gibraltar with accelerating speed, and then

passed through the Strait of Gibraltar and into the Atlantic. Upward bending of isolines across the

Moroccan continental slope extended from Gibraltar to 3deg 20'W, and were strongest in the western

Alboran Sea. Deep Western Mediterranean water was observed at a depth of less than 300 m near

the sill, indicating the passage of this water from the Mediterranean to the Atlantic. Levantine water

mass was concentrated in the central Alboran, turning southward near latitude 4deg 40'W; however it

never crossed the Moroccan continental slope, and partly continued along longitude 36deg 10'

towards Gibraltar. Three floats were deployed in the western Mediterranean at a depth of 60 m to

investigate the upper layer circulation. Their tracks did not show the existence of anticyclonic gyre in agreement with the satellite infrared images of the sea surface temperature. This "anomalous"

behaviour was visible in the satellite infrared images for the period of at least 6 weeks.