Overall objectives in the EU GO project are to assess the promising potential of seismic imaging for physical oceanography, in view of its combination of fine resolution and coverage unmatched by conventional oceanographic measurements. D318 was to provide the means of assessment by obtaining a unique, comprehensive, oceanographic and seismic dataset at the same time and place. Specific objectives for R.R.S. Discovery cruise 318a were to deploy four ADCP moorings, three adjacent temperature-logger moorings and STABLE, in an L-shape array in 750-1000m depth east of Portimao Canyon, carrying out adjacent CTD stations, deploy two OBH moorings, carry out seismic sections using the Ifremer high-frequency air-guns and streamer, accompanied by regular XBT and less frequent XCTD casts. In addition underway data was logged including ship-borne ADCP, surface temperature and salinity, meteorology, gravity and magnetics (to test new NERC magnetometers).

Transit.

Hydrography and physical oceanography cruise for the French Navy's hydrographic and oceanographic service (SHOM).

SHOM cruise

Overall objectives in the EU GO project are to assess the promising potential of seismic imaging for physical oceanography, in view of its combination of fine resolution and coverage unmatched by conventional oceanographic measurements. D318 was to provide the means of assessment by obtaining a unique comprehensive oceanographic and seismic dataset at the same time and place. Specific objectives for R.R.S. Discovery cruise 318b were to (i) recover four ADCP moorings, three adjacent temperature-logger moorings and STABLE, from 750-1000m depth east of Portimao Canyon (ii) perform deep water CTD casts (iii) carry out seismic sections using the NMF supplied Bolt airgun and streamer, accompanied by regular XBT and less frequent XCTD casts, iv) work with MV Poseidon to test novel seismic data acquistion strategies. In addition underway data was logged including ship-borne ADCP, surface temperature and salinity, meteorology, gravity and magnetics (to test new NERC magnetometers).

Hydrography and physical oceanography cruise for the French Navy's hydrographic and oceanographic service (SHOM).

Beautemps-Beaupré cruise.

The objective of the cruise was to improve our understanding of biochemical processes in the near-surface and microlayer of the ocean. We examine gradients in major nutrient concentrations and cycling, production and consumption of key biogases and variability in biological communities between micro-layer, near -surface and deeper water, and between productive and oligotrophic waters along a transect from offshore oligotrophic to coastal upwelling waters off western Spain and Portugal. We also aimed to examine the influence of gradients in physical, biological and photochemical processes at or near the surface micro-layer on the transport of heat and bio-gases across the air-sea interface. Using near-real time satellite imagery of ocean colour in combination with continuous underway measurements of sea surface temperature and chlorophyll fluorescence we identified a suitable oligotrophic site ~25nm off the coast just north of the spain/Portugal border, and reached it on 21 st June and commenced scientific work. We then worked our way inshore via 4 more stations to an upwelling site where science work was concluded on 6th July. The vessel then returned to Falmouth, arriving on 9th July.

Objectives: To quantify marine halocarbon emission variability and latitudinal variation, characterise in situ open ocean atmospheric reactive iodine latitudinal variability and characterise oxidative chemistry perturbation due to oceanic emission of halogens from the Mauritanian upwelling region. Rationale: Transecting from the UK through Biscay, south past the west coast of Africa, through the Mauritanian upwelling, to pass Cape Verde simultaneous to the intensive deployment at the UK SOLAS Observatory on Sao Vicente, the measurements made on Discovery cruise D319 are intended to provide a detailed latitudinal characterisation of marine atmospheric halogen chemistry. This will feed validation and constraint data to regional and global models in projects linked to RHaMBLe. In addition the cruise will address a number of key scientific questions required to determine the global importance of iodine chemistry and to further our understanding of the controls of halogen chemistry in the remote ocean: i) How heterogeneous are the direct halogen sources and on what scale is the heterogeneity - does the upwelling region produce more or less halogens than the 'background' region? ii) What are the relative contributions of I atoms to the remote MBL from I2 and organic iodine? iii) Is sufficient iodine released to the remote MBL to sustain aerosol nucleation or to significantly affect the ozone budget and free radical populations? Measurement Description: Measured species included a variety of halocarbons in both water column and atmosphere and atmospheric boundary layer measurements of I2, OIO and IO by Broadband Cavity Enhanced Absorption Spectroscopy (BBCEAS). A compact version of the FAGE system, developed for the FAAM BAe-146, was deployed to provide measurements of IO or OH / HO2, permitting direct assessment of RHS-induced changes in the oxidising environment through the upwelling region. A range of trace gas monitors was simultaneously deployed to measure O3 and NOx. Aerosol number and size distribution measurements from 3 nm to 20 micron diameter were also made by a range of mobility (SMPS) and optical instrumentation, (OPC and FSSP). Additional aerosol measurements were provided as part of the NERC-funded ACMME project (PI Allan). Measurements of pigments in the surface waters were made by HPLC. Prevailing meteorological conditions were used to direct the cruise in terms of geographical positioning and measurement interpretation, e.g. i) exploitation of any broad flow connection between Cape Verde and the ship to interpret measurements as process studies and ii) identification of in- and out-of-plume conditions to contrast chemistry influenced and uninfluenced by emissions from the upwelling region.