Time-series studies at the Porcupine Abyssal Plain Sustained Observatory

RRS James Cook cruise 231 departed Southampton 1st May 2022, operated in the Whittard Canyon (2-3 May) and the Porcupine Abyssal Plain Sustained Observatory area (4-16th May), returning to Southampton 19th May 2022. The goal of the cruise was to continue time-series observations of the surface ocean, water column, and seafloor at the site, as first studied by NOC (then the Institute of Oceanographic Sciences) in 1985. Also, to service a mooring at Whittard Canyon. These activities are supported by CLASS and EU project iFADO. Additional goals were to deploy a BGC Argo float and investigate particle flux (ANTICS team onboard, with some AtlantECO support). The ongoing Covid-19 pandemic resulted in reduced staff onboard but all operations were completed before the weather changed on 16th May. The main aims were to recover data and infrastructure and deploy replacement moorings at PAP and in the Whittard Canyon, to continue time series sampling at PAP-SO. The Met Office Mobilis buoy was successfully recovered and a similar one was redeployed with a sensor frame at 30m. The sediment traps were successfully turned around at both PAP and the Whittard canyon, this time deploying an Anderson trap. A series of water column observation and sampling operations were successfully carried out with a CTD instrument package. The CTD deployments included pre-and post-deployment calibrations of PAP1 and PAP3 sensors. Surface to 600m observations were made with a new camera frame plus Marine Snow Catchers (the old and new ‘Yuki’ style were used). Other water column observations included underway CO2 SubCtech system and day/night zooplankton nets. The benthic time series was continued with a series of seafloor sediment core sampling, amphipod traps and trawling. A Met Office Biogeochemistry Argo float was deployed but had to be recovered when it developed a fault.