DOI: 10.15493/dea.mims.11722023
title: Processed CTD discrete observations from the Physical-Chemical Oceanography Cruise on the Africana Voyage 077, September 1989

description: Processed Conductivity-Temperature-Depth (CTD) discrete data from the upcast collected between 11 September and 22 September 1989 during Voyage 077 on the FRS Africana, in the Benguela Current Large Marine Ecosystem (BCLME) region on the west coast of Southern Africa.
description: Here we present processed Conductivity-Temperature-Depth (CTD) discrete data from the upcast collected between 11 September and 22 September 1989 during Voyage 077 on the FRS Africana, in the Benguela Current Large Marine Ecosystem (BCLME) region on the west coast of Southern Africa. Neil Brown MK3 and MK4 CTD instruments were used to measure pressure, temperature and conductivity through the water column during research and monitoring cruises between 1983 and 2000. There were several objectives for the Physical-Chemical Oceanography Cruise, covering Physical Environment (PE), Sedimentation and Nutrient cycling (SN), Chemical Environment (CE), Shoal Ecology (SE), Plankton studies (P) and testing of the new AIDA acoustic system with possible estimates of biomass in specific places such as in the baroclinic jets. The objectives included identifying and documenting near-surface and mid-water baroclinic jets west of Cape Columbine and Cape Town using acoustic doppler profiling and Conductivity-Temperature-Depth (CTD) data; observing currents in the upper 200m at regular intervals along the cruise track, using the Acoustic Doppler Current Profiler (ADCP); performing a 30 hour internal tide experiment at the shelf edge west of the Chamais Bay; deploying a series of current meter moorings on the Namibian remote shelf and eastern Cape Basin zones between Chamais Bay and Walvis Bay; servicing a weather station at Pelican Point; recovering a current meter array 90 miles west of Walvis Bay and re-deploying the Kiel sediment trap and current meter array at the same position; deploying the ruggedised Sea Fisheries Research Institute (SFRI) sediment traps in the vicinity of the Orange River and Conception Bay; taking box cores for on-board sediment core incubation at Conception Bay and the same Orange River Mouth site sampled in March 1989; running a set of CTD lines across the shelf to the vicinity of the shelf break; and lastly to draw samples from the labratory seawater sampling probe at regular intervals for fractionation, filtration and calibration of the in-line fluorometer.
description: Neil Brown MK3 and MK4 Conductivity-Temperature-Depth (CTD) instruments were used to measure pressure, temperature and conductivity through the water column during research and monitoring cruises between 1983 and 2000. Temperature was converted from the IPTS-68 scale to the ITS-90 scale, and salinity was computed from conductivity measurements on the 1978 Practical Salinity Scale, according to UNESCO (1991) algorithms. UNESCO (1993) quality control procedures were applied to the data, and obvious erroneous values resulting from problems including electronic spikes, data collection in air, inadequate flow through the conductivity cell, among others, have been removed. Any additional calibrations or corrections have been specified in each data file, where applicable and available.