RRS Discovery D232
Cruise summary report
| Cruise Info. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Ship name (ship code) | RRS Discovery (74E3) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Cruise identifier | D232 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Cruise period | 1998-04-04 — 1998-04-21 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Status | Completed | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Port of departure | Southampton, United Kingdom | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Port of return | Santa Cruz de Tenerife, Spain | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Purpose | Research | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Objectives | 1) To carry out mooring operations associated with long term monitoring of the exchange between the Atlantic and the Mediterranean through the Strait of Gibraltar
2) To study non linear processes resulting from the strong currents in the Strait with new instrumentation uniquely available on RRS Discovery 3) To measure biogeochemical fluxes associated with the upper layer inflow of Atlantic water and the lower layer outflow of Mediterranean water through the Strait. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Chief scientist | Harry L Bryden (Southampton Oceanography Centre) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Cruise report |  (0.95 MB) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Ocean/sea areas | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| General | Mediterranean Sea - Western basin North East Atlantic Ocean (limit 40W) Strait of Gibraltar (Mediterranean Sea) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Specific | Atlantic and the Mediterranean, and the Strait of Gibraltar | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Measurements | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Physical oceanography | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| CTD stations | Quantity: number of stations = 25 Description: 11 in the Western Section, 1 in the Tarifa Narrows Station, 11 in the Eastern Section, 2 additional stations at 200 m depth near the location of the IES moorings prior to the mooring recovery | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| CTD stations | Quantity: number of profiles = 11 Description: TOWYO CTD used to observe the vertical motions of the interface between Atlantic and Mediterranean water during the passage of the tidal bore. Stations were between 1-3 hours duration to observe the characteristics of the leading edge of the bore and of the crests and troughs of the trailing wave train. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| CTD stations | Quantity: number of stations = 29 Description: CTD measurements during hydrographic stations. 2 MkIIIc CTDO's numbers Deep03 (used throughout the cruise) and Deep04. Made up of CTD, altimeter, LoweredACDP, 24-place FSI pylon and 24 x 10 litre water bottles. 2 test stations were made in the Bay of Biscay to assess instrument performance. CTD and LADCP profiles of temperature, salinity, oxygen and east and north velocities as well as water samples at discrete depths. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Subsurface temperature and salinity measurements | Quantity: number of samples = 342 Description: Salinity: 2 salinometers. 2 batches of standard sea water used of which 14 and 4 ampoules were consumed, respectively. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Current profiler (eg ADCP) | Description: Vessel-Mounted Acoustic Doppler Current Profiler provided quantitative estimates of the velocity signatures of the bore and associated large amplitude waves with only a short delay. Attempts were made to use the VM-ADCP measurements to define the depth of the interface between Atlantic and Mediterranean waters by contouring the vertical shear in alongstrait current and determining the depth of maximum shear. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Current profiler (eg ADCP) | Description: Acoustic Correlation Current Profiler. Water profiling and bottom track data continuously from 11-19 April when in the study area. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Current profiler (eg ADCP) | Quantity: number of stations = 20 Description: Lowered ACDP Measurements. Mounted vertically in the centre of the CTD frame. The instrument was set to Water and Bottom Tracking Mode with 10 times 16-meter bins for the whole cruise. Used to measure instantaneous relative velocities of scatterers in the water column. Data from 20 out 27 stations that was downloaded, appeared to be of fine quality. Underway ACDP measurements were used simultaneously with the EK500 to profile the variations in currents associated with the waves. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Other physical oceanographic measurements | Quantity: number of deployments = 11 Description: Moorings deployed as part of the CANIGO programme. 8 were successfully recovered, 2 were not found, and the bottom part was not recovered on 1 mooring. Signatures of 100m amplitude internal waves were measured by acoustic backscatter using EK500 underway profiling. Robust evidence for the waves was simultaneously derived from current profiles measured by the shipboard ACDP, not only from the horizontal velocity but also from the directly measured vertical velocity, and from tow-yo CTD profiles up and down through the interfacial region between Atlantic and Mediterranean waters. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Chemical oceanography | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Oxygen | Description: Samples were drawn from each Niskin bottle following the collection of samples for CFC analysis. Duplicate samples were taken on each cast, usually from the 2 deepest bottles. The Winker whole bottle titration method with amperometric endpoint detection was used (Culberson and Huang, 1987) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Oxygen | Quantity: number of profiles = 24 Description: Water samples taken for the analysis of dissolved inorganic nutrients during the cruise. Analysis performed using the SOC Chemlab Auto-Analyser type II (AAII) coupled to a Digital-Analysis Microsteam data capture and reduction system. Each sample was analysed in duplicate. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Phosphate | Quantity: number of profiles = 24 Description: Water samples taken for the analysis of dissolved inorganic nutrients during the cruise. Analysis performed using the SOC Chemlab Auto-Analyser type II (AAII) coupled to a Digital-Analysis Microsteam data capture and reduction system. Each sample was analysed in duplicate. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Nitrate | Quantity: number of profiles = 24 Description: Water samples taken for the analysis of dissolved inorganic nutrients during the cruise. Analysis performed using the SOC Chemlab Auto-Analyser type II (AAII) coupled to a Digital-Analysis Microsteam data capture and reduction system. Each sample was analysed in duplicate. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Nitrite | Quantity: number of profiles = 24 Description: Water samples taken for the analysis of dissolved inorganic nutrients during the cruise. Analysis performed using the SOC Chemlab Auto-Analyser type II (AAII) coupled to a Digital-Analysis Microsteam data capture and reduction system. Each sample was analysed in duplicate. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Silicate | Quantity: number of profiles = 24 Description: Water samples taken for the analysis of dissolved inorganic nutrients during the cruise. Analysis performed using the SOC Chemlab Auto-Analyser type II (AAII) coupled to a Digital-Analysis Microsteam data capture and reduction system. Each sample was analysed in duplicate. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Contamination | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Trace metals | Quantity: number of samples = 76 Description: The sampling strategy intended to establish end member concentrations within the boundaries of the region for the variously sourced waters passing through the Strait of Gibraltar. 61 samples obtained and filtered onboard, with both filters and filtrate being retained for future analysis. In addition 15 samples were taken for later Os analysis and 2 for dissolved and total Nd in the Mediterranean waters | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Chlorinated hydrocarbons | Quantity: number of profiles = 24 Description: ChloroFluoroCarbon Tracers: A comprehensive tracer data set for CFC-11, CFC-12, CFC-113 and carbon tetrachloride was collected in order to characterise and age the two water masses found in the Mediterranean Sea and also to determine their outflow and spread into the North Atlantic Ocean. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Biology and fisheries | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Dissolved organic matter (inc DOC) | Description: Total and Dissolved Organic Carbon: samples taken from all depths on all CTD stations after CFC and oxygen samples were collected | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Zooplankton | Quantity: number of samples = 180 Description: Longhurst-Hardy Plankton Recorder (LHPR) fished twice during the cruise. The instrument was used to take biological samples at fine depth resolutions of a few metres, using a 280 micron mesh net with a 200 micron cod-end, fished on the conducting deep-tow cable. Tows made to sample the large-amplitude waves formed at 100-150 m depth following the tidal bore. Tows sampled Mediterranean and Atlantic water, as indicated by temperature and salinity, above and below the wave from. Station 13384 at L6N took 94 samples and station 13387 at N3 took 86 samples, each one minute in duration. The spools were preserved whole for later examination in the laboratory. Salinity, temperature and depth were sampled routinely throughout the deployments. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Zooplankton | Quantity: number of deployments = 4 Description: (TUBA) Towed Undulating Bio-Acoustic Sonar was used to measure the spectral reponses at 7 different frequencies to provide an estimate of zooplankton abundance, and ultimately for modelling the size and types of scatterrer in the sampling volume. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Other biological/fisheries measurement | Quantity: number of profiles = 24 Description: Carbon samples. Casts were sampled for nutrients during the cruise. Analysis performed using the SOC Chemlab Auto-Analyser type II (AAII) coupled to a Digital-Analysis Microsteam data capture and reduction system. Each sample was analysed in duplicate. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Data held at BODC | Get data | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Series/Profiles | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 27 CTD/STD cast | Dissolved oxygen parameters in the water column Vertical spatial coordinates Salinity of the water column Temperature of the water column Dissolved oxygen parameters in the water column Vertical spatial coordinates Salinity of the water column Temperature of the water column
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