RRS James Clark Ross Cruises JR265 and JR254D, 27 Nov-24 Dec 2011. Part 1: The Drake Passage hydrographic repeat section SR1b

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

Airflow distortion at instrument sites on the RRS James Clark Ross during the WAGES project

Wind speed measurements obtained from anemometers mounted on ships are prone to systematic errors caused by the distortion of the airflow around the ship's hull and superstructure. This report describes the results of simulations of the airflow around the RRS James Clark Ross made using the computational fluid dynamics (CFD) software VECTIS. The airflow distortion at anemometer sites used during the WAGES project has been quantified at a wind speed of 10 m/s for relative wind directions of 0 (bow-on), 10, 20, 30, 50, 70, 90 and 110 degrees off the bow. The anemometers used in this study were located in the bows of the ship. Temperature sensors were located on the port side of the monkey island. For bow-on flows the anemometers in the bows of the ship experienced relatively small flow distortion. At these sites the flow was decelerated by about 1% of the free stream wind speed. Over the full range of relative wind directions the flow to the R3 sonic is generally accelerated with the largest wind speed biases at flows directly over the beam. The vertical displacement of the airflow increases from around 1 to 2 m for flows directly over the bow, to around 5m for flows over the ships beam as the blockage of the airflow by the ship becomes greater.The airflow distortion at the temperature sensor locations above the monkey island was typically greater than the well-exposed foremast locations. These locations experienced wind speed biases from 6% increase for an airflow directly over the bow, to large decelerations of 55 % when the instruments were in the large recirculation region for flows directly over the starboard side

Metadata for the WAGES instrumentation deployed on the James Clark Ross between May 2010 and September 2011

The RRS James Clark Ross makes meteorological measurements around Antarctica during the austral summer, in the Arctic during the boreal summer and in the Atlantic during passages between the two poles. In May 2010, as part of the WAGES project the ships 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, a commercial directional wave radar "WAVEX" made by the Norwegian firm MIROS was installed.This report describes the metadata for the WAGES instrumentation deployed on the RRS James Clark Ross between May 2010 and September 2011. Sensor serial numbers, dates of sensor changes andproblems with sensors are contained in the associated tables

Metadata for the WAGES instrumentation deployed on the RRS James Clark Ross between May 2010 and September 2013

The RRS James Clark Ross makes meteorological measurements around Antarctica during the austral summer, in the Arctic during the boreal summer and in the Atlantic during passages between the two poles. In May 2010, as part of the WAGES project the ships 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, a commercial directional wave radar "WAVEX" made by the Norwegian firm MIROS was installed. This report describes the metadata for the WAGES instrumentation deployed on the RRS James Clark Ross between May 2010 and September 2013. Sensor serial numbers, dates of sensor changes and problems with sensors are contained in the associated tables

HiWASE: instrument alignments

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°

Possible biases in wind speed measurements from merchant ships

Wind speed measurements obtained from ship-mounted anemometers are biased by the presence of the ship which distorts the airflow to the anemometer. Until recently this bias had only been quantified for a few well-exposed anemometer sites on individual research ships, whereas the magnitude and even the sign of the bias was unknown for anemometers on merchant ships. Three-dimensional numerical simulations of the airflow over a typical tanker/bulk carrier have been performed to quantify the pattern of the airflow above the ship’s bridge. The accuracy of the numerical simulations has been verified by comparison to wind tunnel studies. Typically, the flow is accelerated by up to 18±6 % or decelerated by 100% depending on position. In practice, an anemometer located above the bridge should be mounted as high and as far forwards as possible

RRS James Clark Ross Cruise 52, 11 Sep-17 Oct 2000. AutoFlux trials cruise, UK to Falklands passage

This report describes the work undertaken on the AutoFlux system by SOC staff on the RRS James Clark Ross during the UK to Falklands passage between 11 September and 17 October 2000. This work coincided with the Atlantic Meridional Transect (AMT) 11 cruise (JR52) which ended on 11 October 2000, and is described elsewhere (Woodward, 2000). The SOC presence on the ship was sponsored by John King (BAS) as part of his Q3 (Antarctic Climate Processes) science program.The aim of the cruise was to test and develop the AutoFlux air-sea interaction system and its associated prototype instrumentation. The system is intended to provide real-time air-sea fluxes of momentum, sensible heat, latent heat and CO2, in addition to the usual mean meteorological parameters. The fluxes are calculated via the ‘inertial dissipation’ method (Yelland et al., 1998), using data from various fast-response instruments. Most of the instruments used in the system have been well proved during SOC research cruises over the last 10 years or more, but the dedicated sonic temperature sensor and the infra-red H2O/CO2 sensor are prototype instruments developed by colleagues involved in the AutoFlux project (MAST project MAS3-CT97-0108). Likewise, the logging and processing system is itself based on software systems which have been developed at SOC/IOS since the 1980s, but many aspects of the system are new and were tested and developed further during the cruise. By the fourth week of the cruise the system was automatically producing hourly direct measurements of the air-sea fluxes and was sending summary messages of the data back to SOC via the ORBCOMM satellite communications system in near real time

Metadata for the WAGES instrumentation deployed on the James Clark Ross between May 2010 and September 2011.

The RRS James Clark Ross makes meteorological measurements around Antarctica during the austral summer, in the Arctic during the boreal summer and in the Atlantic during passages between the two poles. In May 2010, as part of the WAGES project the ships 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, a commercial directional wave radar "WAVEX" made by the Norwegian firm MIROS was installed. This report describes the metadata for the WAGES instrumentation deployed on the RRS James Clark Ross between May 2010 and September 2011. Sensor serial numbers, dates of sensor changes andproblems with sensors are contained in the associated tables

RRS James Clark Ross Cruise 52, 11 Sep-17 Oct 2000. AutoFlux trials cruise, UK to Falklands passage

This report describes the work undertaken on the AutoFlux system by SOC staff on the RRS James Clark Ross during the UK to Falklands passage between 11 September and 17 October 2000. This work coincided with the Atlantic Meridional Transect (AMT) 11 cruise (JR52) which ended on 11 October 2000, and is described elsewhere (Woodward, 2000). The SOC presence on the ship was sponsored by John King (BAS) as part of his Q3 (Antarctic Climate Processes) science program. The aim of the cruise was to test and develop the AutoFlux air-sea interaction system and its associated prototype instrumentation. The system is intended to provide real-time air-sea fluxes of momentum, sensible heat, latent heat and CO2, in addition to the usual mean meteorological parameters. The fluxes are calculated via the ‘inertial dissipation’ method (Yelland et al., 1998), using data from various fast-response instruments. Most of the instruments used in the system have been well proved during SOC research cruises over the last 10 years or more, but the dedicated sonic temperature sensor and the infra-red H2O/CO2 sensor are prototype instruments developed by colleagues involved in the AutoFlux project (MAST project MAS3-CT97-0108). Likewise, the logging and processing system is itself based on software systems which have been developed at SOC/IOS since the 1980s, but many aspects of the system are new and were tested and developed further during the cruise. By the fourth week of the cruise the system was automatically producing hourly direct measurements of the air-sea fluxes and was sending summary messages of the data back to SOC via the ORBCOMM satellite communications system in near real time