Details of CTD, Disko west cruise 2009


Dataset identification

Title of datasetCTD, Disko west cruise 2009
Narrative summary of datasetIn September 2009, a ship-based study was carried out in the Davis Strait/southern Baffin Bay along a range of transects covering the area between the west coast of Greenland and Baffin Island (Canada) from 68-72º N . Water temperature, salinity and in situ chlorophyll a (chl. a) measured in 0-500 m depths followed the general hydrographical characteristics of the late summer situation. Surface chl. a concentration based on remote sensing satellite data from September 2009 supported these findings. Measurement of in situ chl. a concentrations revealed a maximum in the subsurface (30-50 m water depths). Thus, spatial distribution of the phytoplankton bloom was often restricted to subsurface rather than the surface waters and therefore not detected by the remote sensing during September.
Summary of processing methodologyBetween September 7 and September 22, 2009, a total of 45 stations were sampled from the research vessel R/V Bjarni Sæmundsson (Marine Research Institute, Reykjavik, Iceland). Sampling was carried out during full 24-h cycles, every 4–6 h. The survey was initiated at Sisimiut (Southwest Greenland) and covered a route of 1,485 nautical miles (nmi). The order of the station numbers corresponds to the chronological sequence of the survey. The survey route transects the main bathymetric and hydrographical features described above. For the ease of presentation, the study area was subdivided into three areas: Canadian Shelf Waters (CSWs), DB, and Greenland Shelf Waters (GSWs). Stations shallower than 700 m are assigned to CSW on the Canadian side and to GSW on the Greenland side, whereas stations deeper than 700 m are defined as DB. One exception to this rule is station st. 37, which is assigned to DB even though it is shallower than 700 m. This was done because it is located in the central part of the study area far off the regular shelves and surrounded by much deeper water. It presumably represents a very localized peak in DB, which has not before been captured in bathymetry data collections (Jakobsson et al. 2012). At all 45 stations, vertical profiles of temperature, salinity and fluorescence were obtained from the surface down to 500 m using a SBE 9 plus CTD (SeaBird Electronics) equipped with a Seapoint chlorophyll fluorometer (Seapoint Sensors Inc). Due to an unfortunate loss of samples, the fluorescence readings could not be calibrated to the study area and are therefore only used as a proxy for the relative differences in Chlorophyll-a concentration between stations.
Project/programmeVertical and horizontal distribution of zooplankton and polar cod in southern Baffin Bay (66–71degrees N) in September 2009
Start date2009-09-07
End date2009-09-22

Responsible organisations

Organisation nameAarhus University,Danish Centre for Environment and Energy
Role of organisationOriginator of Dataset

Dataset availability

Original dataset download link
Dataset formatDelimited
Text or Plaintext
Public accessNo limitations
License for useODC-By


Latitude north boundary71
Longitude east boundary-50.458813491341
Latitude south boundary66.3
Longitude west boundary-70.849438491341
Coordinate reference systemWorld Geodetic System 84
Sea areaArctic Ocean
Baffin Bay
Davis Strait

Data types, collection and processing

Observation typeOther physical oceanographic measurements
Water column temperature and salinity
ParameterVariable fluorescence parameters
Chlorophyll pigment concentrations in water bodies
Salinity of the water column
Temperature of the water column
Instrument typefluorometers
Instrument nameSeapoint chlorophyll fluorometer
Instrument typeCTD
Instrument nameSea-Bird SBE 911plus CTD
Platform typeresearch vessel
Platform nameBjarni Saemundsson
Data quality processing informationOn the basis of the CTD stations, five transects cutting across the main bathymetrical and hydrographical structures of the study area were defined (Fig. 1) and interpolated for salinity, temperature, and fluorescence, respectively (Fig. 2). Transects 1–4 cut across the entire study area, starting in CSW, moving through DB, and ending in GSW. Transect 5 is located mainly in GSW, with only one station in DB (Fig. 1). All transects were characterized by relatively warm water (2.2 C) in the upper water column (0–50 m) (Fig. 2a, d, g, j, m). In CSW, the intermediate water body (50–250 m) consisted of relatively cold water (-1.4 C), which stretched out eastwards into the upper part of the intermediate water body in DB. In GSW, the intermediate water body was relatively warm (2.3 C). The deeper part of the water body (250–500 m) was relatively warm in all three areas (2.1 C) with a gradual increase in temperature from CSW toward GSW. On all transects, the salinity ranged from 30.5 to 34.5, increasing with depth. The salinity was in general lowest in the surface waters (0–50 m) of the CSW and highest at depth (300–500 m) in the GSW (Fig. 2b, e, h, k, n), the latter as a result of the inflow of warm Atlantic water. At any particular depth, salinity always increased toward east. Fluorescent material was only found in the upper 50 m of the water column with slightly higher values in CSW and GSW(0.9) than inDB(0.6) (Fig. 2c, f, i, l, o). St. 1 located on the shallow St. Hellefiskebanke (GSW), which is renowned for its primary production, had the highest fluorescence levels recorded in the study area. However, if st. 1 is excluded, there were significantly higher levels of fluorescent material in CSW than in GSW (p[0.0001, t test).

Process information

Submitting organisationAarhus University, Department of Bioscience, Marine Ecology Roskilde
Submission identifier (UUID)267aaf37-c3a8-406a-8492-761953fb13dd
Date of dataset creation2009-09-22
Date of metadata creation2019-03-26
Date of metadata latest revision2019-05-22
Date of publishing2019-05-24
Processing data centreAarhus University, Department of Bioscience, Marine Ecology Roskilde
Summary record-ID515