Gulf of Cadiz oceanography for comparison with seismic imaging

Abstract

The GO project (European Union-NEST-Adventure funding; www.durac.uk/eu.go) aims to assess the potential of seismic imaging of the water column. a dedicated experiment (April-May 2007, gulf of Cadiz) looked at varying Mediterranean Outflow water (MOW) flow along and down the continental slope. Distinctive MOW properties provide strong reflection from seismic sounding. We aim to relate water properties to mixing and hence (e.g.) tides, internal waves, eddies. Physical oceanography results derive from 500 XBT casts, typical spacing 2km, and moorings: three ACDPs, three temperature strings and near-sea-bed turbulence in line on the north-eastern margin of Portimao Canyon (water depths 740-980m); a fourth ADCP-6 km along-slope in 1015 m depth. CTD and LADCP profiling on an IFM-Geomar research cruise, closely following the seismic sections, supplemented the GO measurements. We examine the structures observed on the principal line through the moorings (five surveys,) and compare with the contemporary seismic data that further constrain observed boundaries. The mooring data and profiles are analysed for tides and internal wave spectra, small-scale structure and turbulence to estimate diffusivity and mixing