The objective of cruise DY039 was to service the moorings of the RAPID 26°N project that are deployed to monitor the Atlantic Meridional Overturning Circulation. For each mooring instruments were recovered, data were downloaded and instruments were redeployed. A number of CTDs were made to calibrate the instruments from the moorings. In addition to the standard instruments used in previous years on the RAPID array, biogeochemical instruments were deployed for the ABC Fluxes project, along with some additional temperature sensors and ADCPs for the MerMeed project. During passage from Southampton to Tenerife trial CTDs were completed in international waters. After a short port call in Santa Cruz de Tenerife, departing on the 26th October work commenced on the eastern boundary sub-array comprising of moorings EBH4, EBH4L, EBH3, EBH2, EBH1, EBH1L, EBHi, EB1 and EB1L. A lander was deployed alongside EBHi to provide delayed-mode data telemetry through timed data pod release. Work on the MAR sub-array commenced on 7th November at mooring MAR3. The other moorings in this sub-array (MAR3L, MAR1, MAR1L, MAR2 and MAR0) were all completed by 12th November. The NOG mooring was also recovered and redeployed as part of the MAR sub-array servicing. Mooring WB6 was serviced on 19th November before transiting to Nassau for customs clearance. The remaining western boundary sub-array moorings (WBADCP, WBAL, WB1, WB2, WB2L, WBH2, WB4 and WB4L) were serviced between the 22nd November and the 30th November before docking in Nassau on the 1st December.

The aim of this cruise was to develop a better understanding of carbon cycling in the pelagic waters of the Porcupine Abyssal Plain (PAP). There were three objectives: 1) Turnaround moorings at the PAP Observatory; 2) Conduct a 1-D time series on the central station of a wide range of biogeochmical processes and to back this up with a mesoscale survey of key variables; 3) To trial the use of Autosub for mesoscale surveys in conjuction with the ship. All objectives were met, although the tops of the moorings were found to be missing probably due to fishing activity and the Autosub trials were incomplete due to vehicle failure. A full mesoscale survey was carried out using the ship and an eleven day time series at the central station was achieved. Friday 23 June [JD174] Scientific party met at 13:00 to agree work plans. The Master gave welcome & safety talk at 15:00. We sailed at 18:00 after a series of delays. The Chief Officer was discharged off sick and a replacement was travelling from Lincolnshire. On reaching Plymouth, the railway shut due to a suicide on the track. The replacement mate required taxi from Plymouth to Falmouth. One of the ship's cranes broken, compromising our ability to handling moorings. The ship's engineers worked flat out yesterday and today and managed to cannibalise parts from other cranes. On sailing we moved into the lee of Falmouth Bay to carry out ship's compass check and then deployed Autosub briefly to check its sensors were working. The sea-state was surprisingly benevolent considering how hard the wind had been blowing for previous 3 days. The skies were still very cloudy. Saturday 24 June [JD175] We made an easy passage with winds BF 3-4. The scientists were finding their sea-legs, with no major problems. An Emergency muster & life boat drill was run at 10:30. We had a discussion about Autosub mission and decide to work the central box at PAP for the first deployment.

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).

There were five main objectives for the trials cruise: The first tests of the Autosub Long Range AUV, testing of the HyBIS video guided grab system, testing of the MYRTLE-X Lander systems, testing of a deep camera system for the Lake Ellsworth probe and test deployments of the PELAGRA neutrally buoyant sediment capture drifters. The working area was about 300 miles south west of the Canary Islands, in international waters, over benthic plains of 4000 m depth, with some tests of the video systems over a isolated sea mount rising to 1200 m depth. Most of the objectives of the cruise where met, with successful diving and control of the Autosub LR, tests of the HyBIS and Ellsworth camera systems, and 3 test deployments and recoveries of two PELAGRA floats. Several wire tests of MYRTLE-X systems were carried out, predominantly successful, but concerns over the release system prevented a deployment of the lander. The tests were all purely engineering, hence no science data were collected.

This equipment trials cruise has provided opportunities for test and verification of technology under development at the Proudman Oceanographic Laboratory (POL), the Scottish Association for Marine Science (SAMS) and the National Oceanography Centre, Southampton (NOC,S). This includes equipment developed during the first year of funding under OCEANS 2025 (theme 8). Testing technology in the ocean environment is invaluable in assessing fitness for purpose. Specifically, the cruise tested: A Spar wave buoy (NOC,S) biogeochemical sensors (NOC,S); an UAV system (NOC,S); a video grab system "HyBis" (NOC,S), A benthic Multicore (NOC,S), A benthic lander and associated torroidal Telemetry buoy (POL), and a shallow tow towfish (POL). Testing in Spanish waters (near Tenerife, Gran Canaria and Fuerteventura) has been invaluable. The time on passage has been minimised (the transition from deep to shallow water is less than a days steaming) and the calm conditions to the southwest of the islands in the consistent prevailing north easterly winds have enabled deployment and recovery techniques to be tried and optimised in safety.

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).

The RRS Discovery cruise 304 was conducted from 12 May to 6 June 2005 from and to Santa Cruz (Tenerife). The cruise was completed as part of the NERC founded RAPID programme to monitor the meridional overturning circulation at 26 N. The primary purpose was to service the eastern boundary and Mid-Atlantic Ridge part of the 26 N mooring array which had previously been serviced during the RRS Charles Darwin cruises 170 and 177. 12 moorings were successfully recovered, however two of the shallow eastern boundary moorings failed to release. Intense fishing activity at these sites is likely to be the cause. 12 mooring and four bottom pressure landers were re-deployed. Data from two bottom mounted inverted echosounders was uploaded via acoustic telemetry. A total of 10 CTD casts to calibrate the mooring sensors were carried out and 3 Argo floats (from the UK Met Office) were launched. The moored sensors are CTD loggers for the most part but also bottom pressure sensors, different types of current meters and inverted echosounders are used to determine the strength and structure of the meridional overturning circulation.

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.

This cruise is part of the UK science contribution to the international SOLAS project (Surface Ocean Lower Atmosphere Study www.uea.ac.uk/env/solas/) which aims to advance our understanding of environmentally important interactions between the ocean and the atmosphere. Data collected during the cruise will help to determine the influence of coastal/shelf regions (20-200 km offshore) on microbiological activity in the ocean and chemical interactions between the ocean and the atmosphere. Deep water containing high concentrations of nutrients such as nitrate, and gases such as nitrous oxide and methane, rises to the surface (upwells) at the Mauritanian shelf edge and moves offshore. These nutrients can be chemically altered by sunlight and used by bacteria and microscopic plants to grow. The gases escape to the atmosphere and contribute to global warming. This cruise will sample the upwelled water as it moves offshore measuring its temperature, salinity, nutrient and gas content and the impact this water has on microbiological growth and atmospheric composition in order to improve international global climate models. The cruise has three scientific objectives: 1. To determine the role of upwelling on the supply, loss and air-sea exchange of climatically important gases produced by plankton 2. To determine the role of light in breaking down upwelled and recently produced dissolved organic matter and in producing climatically important trace gases 3. To determine the impact of nutrient enriched upwelled water on the spatial and temporal variability of plankton community structure and activity and resultant influence on biogenic gas flux

Cruise D344 was primarily used for the annual servicing of the eastern boundary and mid-Atlantic ridge moorings that form part of the RAPID-MOC mooring array across the North Atlantic at 26°N. In addition, the easternmost western boundary mooring, WB6, was serviced and the trial current meter mooring off the island of Abaco, WB-CM, was recovered. As the Discovery had made a faster passage than anticipated, a number of CTD stations were performed along 24° 30'N to augment the hydrography section scheduled to take place in January 2010. The instruments deployed on the RAPID-MOC array consist of bottom pressure recorders, CTD loggers, and current meters which, combined with time series measurements of the Florida Channel Current, and wind stress estimates, will be used to determine the strength and structure of the MOC at 26.5°N.