RRS Discovery Cruise 224, Leg 1, 27 Nov-29 Dec 1996. OMEGA: Observations and Modelling of Eddy scale Geostrophic and Ageostrophic motion. Physical and biological observations in the eastern Alboran Sea (western Mediterranean)

The first leg of RRS Discovery Cruise 224, 27/11/96 - 29/12/96, was one of two cruise programs designed to provide the experimental field observations for the EU MAST 3 project, OMEGA (Observations and Modelling of Eddy scale Geostrophic and Ageostrophic motion). Towing the undulating CTD vehicle, SeaSoar, two large scale and three fine scale SeaSoar surveys were made of the Almeria-Oran front region of the western Mediterranean. In addition a brief SeaSoar survey was made of the head of the Algerian Current. These hydrographic measurements of the upper 370 metres of the water column were accompanied by VM-ADCP and ACCP derived ocean currents, underway physical, chemical and biological analysis of surface water samples, multi-frequency acoustic backscatter measurements, meteorological observations and sea surface radiation measurements. Between the surveys, CTD stations were accompanied by detailed measurements of ocean optical properties at strategic locations along and across the front. In addition 8 towed deployments of a Longhurst Hardy Plankton Recorder were made to look at the change in plankton species composition across frontal zones