A repeat hydrographic section (WOCE section SR1b) across Drake Passage was occupiedduring December 2008 aboard the RRS James Clark Ross (JR194). This is a section across theAntarctic Circumpolar Current at its narrowest point, with the primary objective of this cruisebeing to determine the currents, characteristics and transports of the various water masses.A total of 32 CTD/LADCP stations were sampled across Drake Passage and down to Rothera,of which 30 comprised the SR1b repeat hydrographic section between Burdwood Bank andElephant Island, and the first two were test stations. In addition to temperature, salinity andoxygen profiles from the sensors on the CTD package, water samples from the 24-bottle rosettewere analysed for salinity at each station, in order to calibrate the CTD salinity profiles. Also,samples were collected from the shipís underway system to calibrate and complement the datacontinually collected by the OceanLogger. Full depth velocity measurements were made atevery station by an LADCP (lowered acoustic Doppler current profiler) mounted on the frameof the rosette. Throughout the cruise, velocity data in the upper few hundred metres of thewater column were collected by the shipsí VMADCP (vessel mounted acoustic Doppler currentprofiler) mounted on the hull. Meteorological variables were monitored using the onboardsurface water and meteorological sampling system. Bathymetry data were also collected usinga Simrad EA600 echo-sounder, and 7 Argo floats were deployed. A new addition to thescientific complement was the study of microbial abundance and dynamics within the DrakePassage section. Flow cytometry was used to compare the abundance of dominant microbialplankton groups, and a scintillation counter to assess the productivity rates of thebacterioplankton.The work is a component of the "Sustained Observations" supported by NERC's Oceans 2025programme. This report describes the methods used to acquire and process the data on boardthe ship during cruise JR194
