RRS James Clark Ross Cruise 193, 29 Nov – 08 Dec 2007. Drake Passage repeat hydrography: WOCE Southern Repeat Section 1b – Burdwood Bank to Elephant Island.

A repeat hydrographic section (WOCE section SR1b) across Drake Passage was occupied during November and December 2007 aboard the RRS James Clark Ross (JR193). This is a section across the Antarctic Circumpolar Current at its narrowest point, with the primary objective of this cruise being to determine the currents, characteristics and transports of the various water masses. A total of 42 CTD/LADCP stations were sampled across Drake Passage and down to Rothera, of which 30 comprised the SR1b repeat hydrographic section between Burdwood Bank and Elephant Island. In addition to temperature, salinity and oxygen profiles from the sensors on the CTD package, water samples from the 24-bottle rosette were analysed for salinity at each station, in order to calibrate the CTD salinity profiles. In addition, samples were collected from the ships underway system to calibrate and complement the data continually collected by the OceanLogger. Full depth velocity measurements were made at every station by an LADCP (lowered acoustic Doppler current profiler) mounted on the frame of the rosette. Throughout the cruise, velocity data in the upper few hundred metres of the water column were collected by the ships VMADCP (vessel mounted acoustic Doppler current profiler) mounted on the hull. Meteorological variables were monitored using the onboard surface water and meteorological sampling system. Bathymetry data were also collected using a Simrad EA600 echo-sounder, and a number of ARGO floats and a surface drifter deployed. The work is a component of the "Sustained Observations" supported by NERC's Oceans 2025 programme. This report describes the methods used to acquire and process the data on board the ship during cruise JR193.