The Maltese oceanic front: a surface description by ship and aircraft

Abstract

Simultaneous observations by ship and aircraft of an oceanic fronta ! zone east of Malta in May 1971 show a predominatly north-south boundary between two water masses evidently formed by surface water from the western Mediterranean and by the Ionian Sea. The front is located along the continental slope east of Malta from the southern tip of Sicily to about 3So 30'N where the influences of changing bottom topography and westward-flowing Levantine water probably combine to break up the continuity of the frontal boundary; from that point the front turns to the east southeast and becomes increasingly more difficult to detect from either its temperature or its salinity properties. Airborne infrared radiation thermometry (ART, or sometimes IRT) was used to obtain maps of the sea surface temperature; one detailed survey of the northern part of the front showed meanders of some 15 nautical miles wavelength and 8 to 10 nautical miles wave width (peak-to-peak horizontal deviation). Towed surface thermistor measurements from the ship agreed quite well with the ART measurements, at least in the regions where ART measurements are va~id, i.e. where there is sufficient surface roughness to eliminate sun-glitter problems. Airborne and shipborne expendable bathythermograph measurements were only in fair agreement.