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.

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.

This project was a hydrographic section at latitude 24°N, with physical, chemical and biological measurements. The section was a complete section from continent to continent from North America (Caribbean) to Africa (off the coast of the Western Sahara). The section started and ended in 200 metres water depth, at the edge of the continental shelf. This was a contribution to the international CLIVAR/Carbon repeat hydrography program (http://ioc3.unesco.org/ioccp/Hydrography/New_GlobalMap.html). Climate change will be studied by comparing the new data with historical measurements. Ocean heat transport plays a major role in the coupled ocean-atmosphere climate system. We will study the present-day circulation by calculating the heat and freshwater transported by the ocean across the 24°N latitude. The ocean western boundary current system, in this case the Gulf Stream flowing through the Florida Strait, plays a crucial role in the oceanic heat transport. Therefore a crossing of the Florida Strait will be carried out to establish the status of this important ocean feature. All data arising from the cruise will be lodged and made available via the British Oceanographic Data Centre (BODC), UK.