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This report describes the 17th complete occupation of the Drake Passage CTD section, established during the World Ocean Circulation Experiment as repeat section SR1b. It wasfirst occupied by National Oceanography Centre (previously IOSDL and then SOC) in collaboration with the British Antarctic Survey in 1993, and has been re-occupied most years since then. Thirty two full depth stations were performed during JR265: two test stations, and all 30 of the nominal stations for the SR1b Drake Passage section. An initial result is that the estimated total transport measured across the section was 133 Sv which compares well to an average transport measured from the 16 previous UK cruises of 135 Sv (standard deviation of 7 Sv). In conjunction with the hydrographic cruise, a "Waves Aerosol and Gas Exchange Study" (WAGES) intensive observation cruise JR245D was also carried out. WAGES involves continuous measurement of the air-sea turbulent fluxes of CO2, sea spray aerosol, momentum and sensible and latent heat fluxes, plus directional sea-state and whitecap parameters using systems installed on the ship in May 2010. In addition to the continuous measurements, a number of intensive observation periods (IOPs) have been carried out by WAGES staff on board the ship. These involve deployments of a spar buoy to measure wave breaking and an aerial camera system to measure whitecap fraction. The activities of JR254D are summarised here, but are described in detail in a separate cruise report. Cruise JR264 was carried out by NOC-L staff at the same time as JR265 and JR254D. JR264 is also the subject of a separate cruise report. The CTD was an underwater SBE 9 plus unit equipped with the following sensors: dual temperature and conductivity sensors, a pressure sensor encased in the SBE underwater unit, a SBE-43 oxygen probe, an Aquatracka MKIII fluorometer, a transmissometer, an upwardlooking downwelling PAR sensor, and an altimeter. A downward-looking LADCP (RDI Workhorse Monitor 300 kHz) was deployed on all stations. Various underway measurements were obtained, including navigation, VM-ADCP, sea surface temperature and salinity, water depth and various meteorological parameters. A practical aim during this cruise was to update the detailed guides for each of the hydrographic data streams which were first written duringJR195 in 2009. The hydrographic data analysis was performed using "MSTAR", a suite of Matlab programs developed at NOCS by Brian King and used on the JCR for the first time during JR195.

Alignment offsets between anemometers and motion-sensing instruments are a source of uncertainty for eddy correlation flux measurements made at sea. A previously described laboratory technique (Brooks, 2008) has been utilised to determine the pitch, roll and yaw offsets between flux instruments installed on the weathership Polarfront as part of the HiWASE project. Pitch and roll offsets were determined with an uncertainty of between 0.02° and 0.08°. Yaw offsets were determined with an uncertainty of between 0.5° and 1.2°.

Between 1978 and 2009 the Norwegian weather ship Polarfront made continuous meteorological and surface wave measurements at Station M (66oN 2oE). In September 2006, as part of the UK-SOLAS HiWASE project (Brooks et al., 2009) the ship’s existing systems were complemented by the AutoFlux system (Yelland et al., 2009) to measure the transfers of momentum, heat and CO2 between the atmosphere and the ocean. Similarly, the ship's existing ship-borne wave recorder (SBWR) was supplemented by installing a commercial directional wave radar "WAVEX" made by the Norwegian firm MIROS.This report describes the metadata for the HiWASE instrumentation deployed on the OWS Polarfront between September 2006 and December 2009. Sensor serial numbers, dates of sensor changes and problems with sensors are contained in the associated tables.

This report describes the mobilisation and shakedown cruise of the Norwegian weather ship OWS Polarfront in September 2006. The air-sea turbulent flux system "AutoFlux", a commercial wave measurement system "WAVEX" and a number of digital cameras were installed on the ship as part of the UK-SOLAS project "HiWASE" (High Wind Air-Sea Exchanges). These complemented the ship's mean meteorological sensors and a ship-borne wave recorder (SBWR) both run by the Norwegian Meteorological Institute (DNMI) and an underway pCO2 system run by the Bergen Centre for Climate Research (BCCR).The Polarfront and its predecessors have occupied Station M (66º N, 2º E) for over 60 years.The ship is on station all year round, only leaving for an eight hour port call once every 4 weeks, and an annual refit for 5 days in September. The HiWASE instrumentation was installed in early September 2006, prior to the shakedown cruise P162. The various systems operated continuously from September 2006 until December 2009, when DNMI withdrew the ship from operation.This cruise report describes the instrumentation installed on the ship, including that run by DNMI and BCCR as well as the HiWASE systems, and presents an initial analysis of the data quality from the various systems. Preliminary results are given for the air-sea fluxes of momentum, CO2 and sensible and latent heat. These fluxes were directly measured using the inertial dissipation and/or the eddy correlation (covariance) methods, from a suite of fast response sensors installed on the ship's foremast.This report focuses on the systems as installed for the shakedown cruise. However, over the 3 year deployment period various changes were made: these are described in a separate metadata report (Moat et al., 2010).

This report describes the 16th occupation of the Drake Passage CTD section, established duringthe World Ocean Circulation Experiment as repeat section SR1b. It was first occupied byNational Oceanography Centre (previously IOSDL and then SOC) in collaboration with theBritish Antarctic Survey in 1993, and has been re-occupied most years since then. Thirty onefull depth stations were performed during JR195: two test stations, and 29 of the 30 nominalstations for the SR1b Drake Passage section. Two 500 m stations were added as part of POL'scruise JR198.The CTD was an underwater SBE 9 plus unit equipped with the following sensors: dualtemperature and conductivity sensors, a pressure sensor encased in the SBE underwater unit, aSBE-43 oxygen probe, an Aquatracka MKIII fluorometer, a transmissometer, an upwardlookingdownwelling PAR sensor, and an altimeter. A downward-looking LADCP (RDIWorkhorse Monitor 300 kHz) was deployed on all stations, except for the two 500 m stationswhen it was replaced by a 600 kHz LADCP from Bangor University.Various underway measurements were obtained, including navigation, VM-ADCP, sea surfacetemperature and salinity, water depth and various meteorological parameters.

Accurate wind speed measurements from anemometers on research ships are required to obtain high quality air-sea flux measurements. However, the measurements can be biased by the distortion of the airflow over the ship, i.e. the wind speed can either be accelerated or decelerated by the presence of the ship and the flow of air can be displaced vertically over the ship's superstructure. The computational fluid dynamics software VECTIS was used to numerically simulate the airflow over the Ocean Weather Ship Polarfront. The airflow distortion at six anemometer sites has been quantified for a wind speed of 10 ms-1 blowing a) directly over the bows of the ship and b) over the ship’s starboard beam. The wind speed errors ranged fromdecelerations of about 1 % for an airflow directly over the bow to accelerations of 10 % for the beam-on flow.

Wind speed measurements are obtained from anemometers located on research ships. Even though the anemometers are usually positioned in well-exposed locations the presence of the ship’s hull and superstructure distorts the airflow to the anemometer and biases the wind speed measurements. Previous studies have shown biases of up to 10 % for bow-on flows, and that the biases generally increase for other wind directions. Corrections for the effects of the flow distortion are vital, as these data are used for satellite validation and in climate related studies. Therefore, the computational fluid dynamics (CFD) package VECTIS is used to numerically simulate the airflow over ships and derive corrections for this effect.A VECTIS simulation of one ship at one wind direction currently takes approximately one month to perform on a typical UNIX workstation. Therefore, it would be impractical to study the airflow over a large number of research ships and/or a large number of wind directions. A faster method (the “steady-state solver”) for VECTIS simulations has been available for some time, but requires significant increases in computational speed and memory which have only recently become widely available. This report presents a comparison of VECTIS simulations using the steady-state solver with both previous VECTIS studies and in situ wind speed measurements.Use of the steady-state solver requires a higher mesh density but also cuts model convergence times from weeks to days, allowing fine-resolution models to be run without impractical time constraints. The results of this study show that in regions where the flow distortion is high, the increased mesh density results in significant improvement in the comparison between modelled and in-situ wind speeds.

Wind speed and air-sea flux measurements made from instrumentation on ships are affected by the airflow distortion created by the presence of the ship. The airflow can be eitheraccelerated or decelerated depending on the shape of the ship and the location of the anemometer. The computational fluid dynamics (CFD) package VECTIS was used to examinethe extent of the flow distortion at potential anemometer locations on the foremast platform of the RRS "James Cook". This technique has been previously used to study the airflow over many research ships, but this is believed to be the first time it has been applied to a research ship in the design/build stage.CFD modelling of the airflow over the ship showed that the foremast platform of the RRS "James Cook" is a good location to locate instrumentation and make high quality air-sea flux measurements. The wind speed is decelerated by about 2 % of the freestream wind speed for bow-on flows at well-exposed anemometer sites on the foremast platform. For relative wind directions up to ±30° of the bow the airflow is accelerated by up to 5 %.The ship’s anemometers are located on the main mast and are relatively close to the ship’s large satellite communication radome. For winds within 15° of the bow the wind speeds at these anemometer sites are accelerated by up to about 7 %. For wind directions at ±30° the satellite radome has a significant effect on the flow and the wind speeds will be severely biased, with the magnitude of the bias varying rapidly with wind direction and the angle of pitch of the ship. It is strongly recommended that these anemometers be moved higher up and further away from the mast.