DOI: 10.15493/dea.mims.01332023
title: Processed underway Thermosalinograph (TSG) observations from the SAMBA Monitoring Line cruise on the Algoa Voyage 285, September 2022

description: Algoa Voyage 285
description: Here we present the 6-second resolution processed Thermosalinograph (TSG) data collected during the The South Atlantic Meridional Overturning Circulation Basin-wide Array (SAMBA) Monitoring Line cruise, which was conducted on the Algoa Voyage 285 between 27 September 2022 and 07 October 2022. A SeaBird SBE45 Thermosalinograph (TSG) is used to opportunistically collect underway near-surface temperature and conductivity measurements during research and monitoring cruises. Water is continuously pumped to the TSG from an intake located in the hull of the vessel, and the observations are continuously interfaced with navigational information. A temperature sensor close to the intake provides temperature measurements of the incoming water (T1). The temperature of the water inside the conductivity cell (T2) is used to accurately compute salinity (S) from the conductivity measurements (C). The cruise operated from Slangkop, off Cape Town, westwards to 11° E, in the South Atlantic Ocean along the SAMBA transect and south of Hondeklipbaai on the West coast. The objectives of the cruise were to recover an Acoustic Doppler Current Profiler (ADCP) mooring (M4) along the Integrated Ecosystem Programme (IEP)’s Scarborough Monitoring line to collect current data on the Benguela Jet Current; recover 3 x tall moorings on the SAMBA transect (M8; M9 & M10), incorporating ADCP’s and Sea-Bird Microcats; complete 21 Conductivity, Temperature, Depth (CTD) casts to a maximum depth of ~1200m (using Hydro winch) along the SAMBA transect; recover; service and re-deploy 1 TRAFFIC sediment trap mooring (SBUS East-03), south of Hondeklipbaai; undertake Chlorophyll and Oxygen sampling at CTD stations and underway along SAMBA transect; collect underway Thermosalinograph (TSG); Surface Photosynthetically Active Radiation (SPAR) and Ship-mounted Acoustic Doppler Current Profilers (S-ADCP) data and provide training to newly employed Department of Forestry, Fisheries and the Environment (DFFE) personnel and interns.
description: The SeaBird SBE45 Thermosalinograph (TSG) is used on the Algoa for the collection of underway near-surface temperature and conductivity measurements. The underway seawater is obtained from a depth of 5m below the surface and pumped through the TSG. Data is collected using the most recent SeaBird (SBE) SeaSave software and processed using the most recent SBE data processing software. The software was set to record data at 6 second intervals for the duration of the cruise, between 27 September 2022 and 07 October 2022. Data was collected in the southern part of the Benguela Current Large Marine Ecosystem (BCLME) region on the west coast of South Africa. Unreliable TSG measurements can result from a variety of problems encountered during the cruises, including insufficient water flow, extreme air bubbling during severely adverse weather conditions, debris trapped in the system, or a variety of electronic failures. Detailed visual inspection of the ship trajectory and TSG measurements, as well as comparisons with other concurrent and historical near-surface measurements, and expert knowledge of local conditions, were used to identify and remove all unreliable data.