CD170 was a collaborative cruise with the Knorr cruise KN182_2. The latter cruise was conducted between 2 May 2005 and 26 May 2005. These cruises were completed as part of the UK Natural Environment Research Council (NERC) funded RAPID Programme and the US National Science Federation (NSF) funded MOCHA Programme to monitor the Atlantic Meridional Overturning Circulation at 26.5 degrees North. The primary purpose of both cruises was to service the 26.5 degrees North mooring array deployed in 2004 during RRS Discovery cruises D277 and D278. These cruises are the first annual refurbishment of this array.

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.

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 goal of this cruise was to recover and redeploy some RAPID-MOC moorings near the Eastern Boundary as part of our six-month turnaround programme. Specific cruise objectives were to: 1. Recover moorings EB1 (24 microcats) and EB2 (MMP profiling from 50m to 2500m with microcats and current meters below), two principal tall eastern boundary moorings, sited on a Topex crossover point near 24N, 24W. 2. Redeploy EB1 (24 inductive microcats plus the telemetry system) and EB2 (MMP mooring). 3. Deploy EBADCP to replace the instrument deployed in April but trawled after 10days and recovered by the R/V Poseidon. 4. Deploy two URI Pressure Inverted Echo Sounders. One deployed in 1000m and one in 5000m next to the BPR lander at mooring EB1. 5. CTD stations for pre and post deployment calibrations of all mooring instrumentation. 6. Search for and if possible recover MMP mooring EB2 deployed in April 2004 and located 100km north south of Gomorra in October 2004.

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.

CR Corica 0903 Eastern Boundary Current; Antartic Intermediate Water; Thermohaline Circulation; North Atlantic Oscillation; Climate Variability and Predictability; Geostrophic Transport: inverse model; Total Transport.