HAFRANNSÓKNASTOFNUNIN

Marine Research Institute

Reykjavík, Iceland

VEINS@ICES HAFRÓ MAIN










CRUISE REPORT

CRUISE NUMBER: B09 - 98
(September 1998)


















SCIENTIFIC OBJECTIVES

The B09-98 cruise was carried out by the Marine Research Institute (MRI) on the RV Bjarni Sæmundsson with the following aims:

  1. To carry out long-term hydrographic investigations on standard sections in the Denmark Strait. The investigations included CTD-casts together with samplings for nutrient and oxygen-analysis. Included in the observation work is MRI's role in VEINS, a program with the objective of measuring and modeling the variability of fluxes between the Arctic Ocean and the Atlantic with view on implementing a longer term system of measurements needed to understand the high-latitude oceans steering role in decadal climate variability. Funding is provided by the EU MAST-III programme and the participants in the project. The work on this cruise was part of the following VEINS tasks:

    1. Measuring the Denmark Strait Overflow. (Task 1.4.1)
    2. Determining the water mass properties of the Denmark Strait Overflow. (Task 1.4.2)
    3. Improving estimation of the freshwater flux to the North Atlantic via the East Greenland Current. (Task 1.4.3)
    4. Measuring the inflow of Atlantic Water to the Iceland Sea. (Task 1.4.4)

  2. Recover and redeploy an ADCP mooring on the Látrabjarg section in the Denmark Strait (DS1, VEINS task 1.4.1) and three Aanderaa current meter moorings NW and E of Iceland in the East Greenland Current and East Icelandic Current (IS6, IS9 and KR4, VEINS task 1.4.3). Deploy an Aanderaa current meter mooring NW of Iceland (IS7, VEINS task 1.4.3) complementing the two already existing current meter moorings on the Kögur section (IS6 and IS9).

  3. Collect water samples for the determination of pCO2, total carbonate, delta-C13, oxygen, nutrients, iodine-129 and the sulfur hexafluoride (SF6) tracer, as part of the ESOP-2 program.

  4. Collect water samples for determination of total carbonate, oxygen and nutrients as part of the ESOP-2 program. These samples are for time series which are intended to show variability with time and carbon-nutrient relationships.

  5. Collect continuous surface data on temperature, salinity and pCO2, for the ESOP-2 program to complement data from the occupied stations.

  6. Collect samples for analysis of Cesium-137 (Icelandic Radiation Protection Institute).


CRUISE NARRATIVE

The RV Bjarni Sæmundsson left Reykjavík harbor at 2100 hours on the 1th of September 1998 for the B09-98 cruise.

The vessel headed for station 9 on the Faxaflói section, continuing to the ADCP mooring site (DS1) on the Látrabjarg section in the Denmark Strait, where low visibility due to fog made a service impossible. Instead the western leg of the section was occupied with CTD stations. Returning to the ADCP-mooring site visibility was still low, however a window with clear weather was experienced, during which the mooring was successfully serviced. The ship then headed for the Icelandic side of the Kögur section which was occupied with CTD-stations right to the ice-limit. During the approach towards Greenland three current meter moorings were successful serviced (IS6 and IS9) and deployed (IS7). From the Kögur section the vessel headed for and reached the station Siglunes 8. Due to limited time and unfavorable weather forecast a further progress eastwards was not possible. Meaning that the service/rescue of current meter mooring KR4 on the Krossanes section had to be postponed to a later cruise in the area. The mooring which was deployed in June 1997 did not response in June 1998 possibly due to a suggested instrumental failure in the release warned for by the supplier. Instead the ship returned to station Kögur 7 which was occupied as an alternative ESOP station and arrived to Reykjavík at 2200 on September 10th 1998.

Both sections occupied in the Denmark Strait during the cruise are part of the VEINS programme. Locations of the sections are shown in Figure 1 as well as locations of current meter moorings in VEINS tasks 1.4.1 and 1.4.3 (indicated by m).

HYDROGRAPHY

The hydrographic work was carried out with two independent CTD-water sampling units both equipped with Seabird Inc. SBE 911plus CTD's. The first unit, a MRI made rosette equipped with 12 modified Hydro-Bios 1.7 liter water bottles and a General Oceanics underwater unit, was used for all standard CTD stations. The other unit (referred to as Unit B) comprised of SBE 32 rosette equipped with 12 Go-Flo 8 liter water samplers was used for chemical sampling on ESOP-2 stations. Both units were equipped with newly calibrated temperature and conductivity sensors and water samples were collected at deepest sampling level on all stations for calibration purposes.

CTD (SBE 911plus CTD System) Sensor Status.

	    Temp. Calibr.  Cond. Calibr.
	   sensor date    sensor date

Unit A       2021 06-08-98  1643 07-08-98
Unit B        943 06-08-98   498 07-08-98

CHEMISTRY

Samples for oxygen measurements were collected in 60 ml bottles, and Winkler reagents added. Samples were then placed in a dark cold storage until the time of analysis. Oxygen concentration was determined using a modified Winkler method.
Samples for nutrient analysis, nitrate, phosphate and silicate, were collected on selected stations, in 250 ml polyethylene bottles. Samples were frozen, for later analysis in land on a ChemLab auto-analyzer.
Samples for pCO2 and total carbonate were collected on 4 stations in 500 and 250 ml bottles, preserved with mercury chloride and placed in cold storage.
Samples for delta carbon-13 were collected from the surface at 1 stations and a full profile was collected from 1 station. The samples were preserved with mercury chloride.
Samples for sulfur-hexafluoride (SF6) were collected at 3 stations in 500 ml bottles supplied by the Gothenburg University and placed in cold storage.
Samples for iodine-129 profile were collected at 3 station in 1 liter polyethylene bottles supplied by Centre de Spectrometrie Nucleaire et de Specrometrie de Masse.

MOORINGS

During the B09-98 cruise the following current meter moorings were serviced (VEINS task 1.4.1 and 1.4.3).

St.id.	     Position       Water Instr. Type           Serial  Date    Notes
	Lat.	  Lon.	    depth depth			no.
DS-1	66 04.83N 27 05.98W   649   643  ADCP 75 KHz     1287	040998	recovered
DS-1	66 04.87N 27 04.39W   650   643	 ADCP 75 KHz     1287	050998	deployed
IS-6	68 07.45N 25 16.07W   792    80	 Aanderaa RCM7	 8744	060998	recovered
IS-6	68 07.45N 25 16.07W   792   500	 Aanderaa RCM7	 9976	060998	recovered
IS-9	67 56.00N 24 40.00W  1414    80	 Aanderaa RCM7	11987	060998	recovered
IS-9	67 56.00N 24 40.00W  1414   500	 Aanderaa RCM7	  172	060998	recovered
IS-9	67 56.00N 24 40.00W  1414  1364	 Aanderaa RCM7	12317	060998	recovered
IS-9	67 56.12N 24 40.74W  1402    80	 Aanderaa RCM7	 8743	060998	deployed
IS-9	67 56.12N 24 40.74W  1402   300	 Aanderaa RCM7	12316	060998	deployed
IS-9	67 56.12N 24 40.74W  1402  1350	 Aanderaa RCM7	12559	060998	deployed
IS-6	68 07.31N 25 15.67W   814    80	 Aanderaa RCM7	12315	070998	deployed
IS-6	68 07.31N 25 15.67W   814   500	 Aanderaa RCM7	 7332	070998	deployed
IS-6	68 07.31N 25 15.67W   814   764	 Aanderaa RCM7	12560	070998	deployed
IS-7	67 32.04N 23 44.66W   819    80	 Aanderaa RCM7	11987	080998	deployed
IS-7	67 32.04N 23 44.66W   819   300	 Aanderaa RCM7	 9976	080998	deployed
IS-7	67 32.04N 23 44.66W   819   750	 Aanderaa RCM7	12317	080998	deployed


RESULTS

All the goals of the cruise were achieved (see list of stations and cruise track-Figure 1). The trial for rescue of a mooring east of Iceland (KR-4) deployed in June 1997 had due to time lack to be postponed to a later cruise.

Preliminary inspection of the CTD data showed both in the TS-diagrams from the Látrabjarg and Kögur sections as well as the salinity and temperature sections (see below) the ongoing increase since 1997 compared with recent years indicating favorable inflow of Atlantic water into the North Icelandic coastal area. The fresh water flow in the East Greenland Current was also quite pronounced along with drift-ice off the East Greenland coast to a wider extent than normal for this time of the year, but less so than the previous year (1997). Results of the ADCP mooring of the overflow in the deep channel in the Denmark Strait reveals for the time period September 1996 - September 1998 mean along channel velocities of about 0.5 m/s and temperatures around 0ºC.

Preliminary TS-diagrams from the Látrabjarg and Kögur sections show the results above. In addition are preliminary potential temperature and salinity sections shown for Látrabjarg (Fig. 3a and Fig. 3b) and Kögur (Fig. 4a and Fig. 4b) sections respectively, of which both are part of the VEINS programme. For location of the above sections and mooring sites see Figure 1 and the station numbers.


CONTACT

In case of further information contact:

Svend-Aage Malmberg Email: svam@hafro.is
Jóhannes Briem Email: briem@hafro.is
Héðinn Valdimarsson Email: hv@hafro.is
John Mortensen Email: johnm@hafro.is

or by mail:

Att. name
Hafrannsóknastofnunin
(Marine Research Institute)
P.O. Box 1390
Skúlagata 4
121 Reykjavík
Iceland

or

Tel. (+354) 55 20240
Fax. (+354) 56 23790




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