DOI: 10.15493/dea.mims.01212023
title: Processed underway Thermosalinograph (TSG) observations from the Benguela Air-Sea CO2 and Heat Flux Experiment on the Algoa Voyage 278, December 2021

description: Algoa Voyage 278
description: Here we present the 6-second resolution processed Thermosalinograph (TSG) data collected between 06 December and 19 December 2021 during the Benguela Air-Sea CO2 and Heat Flux Experiment cruise on the Algoa Voyage 278. 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 on the West Coast of South Africa at a fixed location between Station 4 and 5 of the St. Helena Bay monitoring line (SHBML) with the ship's bow into the wind. The objectives of the cruise were to examine, using high-resolution Eddy Co-Variance (EcV) and in situ observations, the role of the ocean “cool skin” on the air-sea flux of CO2 and heat; to examine, through high-resolution observations, the impact of the vertical temperature gradient in the upper 10m of the water column on the estimation of the air-sea flux; to examine the sensitivity of 1 and 2 under a wide range of diurnal and synoptic wind stress and surface layer mixing conditions; to link the variability in the temperature gradients and pCO2 to mixed layer dynamics in response to the interaction of wind-linked mixing and heat-linked stratification; to understand the synoptic scale variability of the CO2 and heat fluxes; to understand how synoptic scale influence diurnal variability of Dissolved Inorganic Carbon (DIC) and Total Alkalinity (TA); to investigate how representative the bulk heat flux parameterisations are to the true EcV heat fluxes, particularly over sharp lateral temperature gradients; to determine the respective role of fine-scale lateral oceanic processes (submesoscales) and synoptic atmospheric variability to the leading order variability of surface heat fluxes and to conduct Top predator population including Seabirds, whales, dolphins, seals, etc.
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 06 December 2021 and 19 December 2021. 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.