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.

The purpose of the cruise was the refurbishment of an array of moorings on the mid-Atlantic Ridge and off the Moroccan Coast at nominal latitude of 26.5°N. The moorings are part of an Atlantic-wide mooring array for monitoring the Atlantic Meridional Overturning Circulation and Heat Flux. The array is a joint UK/US programme and is known as the RAPID-WATCH/MOCHA array. The RAPID transatlantic array consists of 24 moorings of which 21 are maintained by the UK, and 20 bottom landers of which 16 are maintained by the UK. The moorings are primarily instrumented with self logging instruments measuring conductivity, temperature and pressure. Direct measurements of currents are made in the shallow and deep western boundary currents. The bottom landers are instrumented with bottom pressure recorders (also known as tide gauges), measuring the weight of water above the instrument. A sediment trap mooring NOGST was also recovered and redeployed for the Ocean Biogeochemistry and Ecosystems Group at the NOCS. CTD stations were conducted at convenient times throughout the cruise for purposes of providing pre and post deployment calibrations for mooring instrumentation and for testing mooring releases prior to deployment. Shipboard underway measurements were systematically logged, processed and calibrated, including: waves (spectra of energy and significant wave height), surface meteorology (air pressure, temperature, wind speed and direction and radiation (total incident and photosynthetically active), 6m depth sea temperatures and salinities, water depth, navigation (differential GPS measurements feeding two independent and different receivers, heading, pitch and roll from a four antenna Ashtec ADU5 receiver, gyro heading and ships speed relative to the water using an electromagnetic log). Water velocity profiles from 15m to approximately 500m depth were obtained using a ship mounted 75 kHz acoustic Doppler current profiler. Seawater samples from CTD stations and of the sea-surface were obtained for calibration and analysed on a salinometer referencing these samples against standard sea water. For velocity data (wind and currents) measured relative to the ship considerable effort was made to obtain the best possible earth-referenced velocities. Four APEX Argo floats supplied by the Met Office were deployed at pre-assigned locations, filling gaps in the network.

The objective of cruise JC103 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. During passage from port of Spain to Nassau trial CTDs were completed in the waters of the Turks and Caicos Islands. After departing Nassau on 29th April work commenced on the western boundary sub-array comprising of moorings WBADCP, WBAL, WB1, WB2, WB2l, WB2h, WB4 and WB4L. The ship returned to Nassau on 6th May to disembark one person before sailing east once again. The final mooring of the wester sub-array was serviced on 8th May before continuing east to the mid-Atlantic Ridge (MAR) sub-array. Work on the MAR sub-array commenced on 13th May at mooring MAR0. The other moorings in this sub-array were MAR1, MAR1L, MAR2, MAR3 and MAR3L were all completed by 18th May. On the following day the NOG mooring was deployed and as the ship transited to the astern sub-array the first of 5 Argo floats was deployed on 21st May. The eastern boundary sub-array starts at EB1, which was serviced on 23rd May. Following this moorings at EB1L, EBHi, EBH1, EBH2, EBh3,EBh4 and EBH4L in the following days up until 31st May. A number of CTDs were completed form 31st may to 2nd June.

This cruise was completed as part of the United Kingdom Natural Environment Research Council (NERC) funded RAPID Programme to monitor the Atlantic Meridional Overturning Circulation at 26.5ºN. The primary purpose was to service the Eastern Boundary and Mid-Atlantic ridge sections of the 26.5ºN mooring array. The Rapid-MOC array of moorings was deployed across the Atlantic to set up a pre-operational prototype system to continuously observe the Atlantic Meridional Overturning Circulation (MOC). This array will be further refined and refurbished during subsequent years as part of the Rapid-WATCH programme. The instrumentation deployed on the array consists of a variety of CTD loggers, current meters, bottom pressure recorders, and Inverted Echo-sounders, which, combined with time series measurements of the Florida Current and wind stress estimates, can be used to determine the strength and structure of the MOC.

The cruise is a component of RAPID-WATCH, whose objectives are: to deliver a decade-long time series of calibrated and quality-controlled measurements of the Atlantic MOC from the RAPID-WATCH array and; to exploit the data from the RAPID-WATCH array and elsewhere to determine and interpret recent changes in the Atlantic MOC, assess the risk of rapid climate change, and investigate the potential for predictions of the MOC and its impacts on climate. Objectives of this cruise: to recover, calibrate and redeploy moorings from the eastern boundary and mid-Atlantic ridge subarrays of the 26.5N line of RAPID moorings.

The aims of this cruise were to elucidate the processes responsible for controlling iodocarbon concentrations and provide a dataset that can be used to develop modelled estimates of iodocarbon sea-air fluxes in tropical Atlantic waters.

The three key objectives of our original proposal were to test: 1. The hypothesis that mantle upwelling and melting is focused at the centres of slow spreading ridge segments and transposed by sub-horizontal flow away from there. 2. The hypothesis that plate accretion and separation mechanisms are fundamentally different in 'magma-starved' areas. 3. Mechanisms of detachment faulting and extensional strain localisation in the lower crust and upper mantle. We proposed to achieve these objectives by detailed surveying and sampling across an extensive region of magma-poor seafloor spreading around Fifteen Twenty Fracture Zone (FTFZ), coupled with microstructural, geochemical and palaeomagnetic analyses. TOBI deep-towed sidescan and magnetic data were to be obtained both to inform the choice of sampling sites and to aid in structural, lithological and geodynamic interpretations. We spent 29 days on the Mid-Atlantic Ridge (MAR) in the vicinity of 13 to 15N. We collected multibeam ship-based bathymetry, gravity and magnetic data and TOBI sidescan, magnetic and water-column data from a total area of about 8,000 km2. We recovered samples from 47 drill and dredge stations throughout the area, in support of the objectives.

These mooring operations were completed as a part of the United Kingdom Natural Environment Research Council (NERC) funded RAPID Programme to monitor the Atlantic Meridional Overturning Circulation at 26.5°N. The primary purpose of this cruise was to service the Eastern Boundary and Mid-Atlantic Ridge sections of the 26.5°N mooring array first deployed during RRS Discovery cruises D277 and D278 (SOC cruise report number 53), and serviced in 2005 during RRS Charles Darwin cruise CD177 (NOCS cruise report number 5), in 2006 on RRS Discovery cruise D304 (NOCS cruise report number 16) and FS Poseidon cruises P343 and P345 (NOCS cruise report number 28) and in 2007 on RRS Discovery cruise D324 (NOCS cruise report number 34). Cruise D334 started and finished in Tenerife, Spain and covered the Eastern Boundary and Mid-Atlantic Ridge moorings deployed on D324 and P343. This cruise was the fourth annual refurbishment of the Eastern Boundary and Mid-Atlantic Ridge sections of the mooring array. The array will be further refined and refurbished during subsequent years. The instruments deployed consist of a variety of current meters, bottom pressure recorders, CTD loggers and Inverted Echosounders, which, combined with time series measurements of the Florida Straits current and wind stress estimates, will be used to determine the strength and structure of the MOC at 26.5°N.