Departure: Reykjavík, Iceland, May 17th 1999
Arrival: Reykjavík, Iceland, June 03th 1999
Ólafur Ástthórsson, Chief scientist
Héðinn Valdimarsson, Physical Oceanography
Svend-Aage Malmberg, Physical Oceanography
Jóhannes Briem, Physical Oceanography, moorings
Magnús Danielsen, Physical Oceanography
Jón Ólafsson, Chemical Oceanography
Ása Kristjansdóttir, Chemical Oceanography
Kristinn Gudmundsson, Phytoplankton
Kristín Valsdóttir, Phytoplankton
Agnes Eydal, Phytoplankton
Ástþór Gíslason, Zooplankton
Sara Smolenack, Zooplankton, University of New Hampshire, USA
Dorinda R. Ostermann, Sediment trap, Woods Hole Inst., USA
The B07-99 cruise was carried out by the Marine Research Institute (MRI) on the RV Bjarni Sæmundsson with the following aims:
The RV Bjarni Sæmundsson left Reykjavík harbor at 2000 hours on the 17th of May 1999 for the B07-99 cruise.
The vessel headed for the Faxaflói section towards East Greenland, from there to the Látrabjarg and then to the Kögur sections in the Denmark Strait, where bad weather hampered the work and not all the standard stations could be reached including the service of the VEINS current meter mooring IS8 and the Hornbanki section. The vessel then headed eastwards into North Icelandic waters to the Húnaflói, Siglunes, Langanes NE, Langanes E and Krossanes sections, recovering 4 VEINS current meter moorings in the East Icelandic Current. From there the vessel headed for the Stokksnes, Ingólfhöfði, Háfadjúp and Selvogsbanki sections and arrived to Reykjavik at 1000 hour on June the 3th 1999.
Sections confined to VEINS are those of Faxaflói, Látrabjarg, Kögur, Langanes NE and Krossanes. Locations of hydrographic sections and current meter moorings (IS8, LNA1, LNA2, KR4 and KR6, indicated by m, VEINS task 1.4.3 and 1.4.4) are shown in Figure 1.
The hydrographic work was carried out with a CTD-water sampling unit equipped with a Seabird Inc. SBE 911plus CTD. The sampling unit, a MRI made rosette equipped with 12 modified Hydro-Bios 1.7 liter water bottles and a General Oceanics underwater unit, was used on all standard CTD stations. During the cruise two Seabird Inc. SBE 911plus CTD units were used both in combination with a Sea-Tec fluorometer and a transmissometer. Both CTD units made use of the same newly calibrated temperature and conductivity sensors and water samples were collected at deepest sampling level on all stations for calibration purposes.
Temp. Calibr. Cond. Calibr. sensor date sensor date Unit A 2021 17-02-99 1643 19-02-99
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 freezed, for later analysis in land
on a ChemLab auto-analyzer.
Samples for pCO2 and total carbonate were collected on 6 stations
in 500 and 250 ml bottles, preserved with mercury chloride and placed in cold storage.
Samples for delta carbon-13 were collected at 2 stations as full profile.
The samples were preserved with mercury chloride.
Samples for oxygen-18 were collected at 2 stations as full profile.
During the B07-99 cruise the following current meter moorings were serviced (VEINS task 1.4.3).
St. id. Position Water Instr. Type Serial Date Notes Lat. Lon. depth depth no. LNA-1 67 05.00N 13 45.00W 722 80 Aanderaa RCM7 10858 280599 recovered LNA-1 67 05.00N 13 45.00W 722 300 Aanderaa RCM7 11986 280599 recovered LNA-2 67 30.00N 13 16.00W 1712 80 Aanderaa RCM7 12307 280599 recovered LNA-2 67 30.00N 13 16.00W 1712 300 Aanderaa RCM7 12306 280599 recovered LNA-2 67 30.00N 13 16.00W 1712 1665 Aanderaa RCM7 6934 280599 recovered KR-6 65 00.00N 09 00.00W 1375 100 Aanderaa RCM7 12310 290599 recovered KR-6 65 00.00N 09 00.00W 1375 300 Aanderaa RCM7 12309 290599 recovered KR-6 65 00.00N 09 00.00W 1375 1321 Aanderaa RCM7 12305 290599 recovered KR-4 65 08.60N 11 11.07W 626 150 Aanderaa RCM7 12308 300599 recovered KR-4 65 08.60N 11 11.07W 626 265 Aanderaa RCM7 00172 300599 recovered
Most of the goals of the cruise were achieved except the following: (see list of stations and cruise track-Figure 1)
Click your way through the cruise track , i.e. by clicking in the left or right part of the section name you will get potential temperature or salinity sections of the section respectively.
The main result of the hydrographic observations in Icelandic waters in Spring (May-June) 1999 were the following (see e.g. Fig. 12a , Fig. 12b , Fig. 13a , Fig. 13b , and Fig. 14 ):
The Atlantic Water (Irminger Current) south and west of Iceland showed high temperatures (7-8°C) as well as salinities (35.0-35.25). These conditions are a continuation of findings from 1997 which revealed values higher than ever found since the early sixties. Further more the inflow of Atlantic water into North Icelandic waters was this spring quite pronounced reaching the area east of Siglunes (3-5°C, > 35.0) and stronger than in previous years even as far back as 1980. It even reached values as high as 34.8 in salinity east of Langanes NE. Also, no cold and low saline water in the surface layer was observed as had been the case during the last 3 to 4 years. Farther off at the shelf break in North Icelandic waters the cold (0-2°C) Polar/Arctic water was found as usual. In the shelf area east of Iceland temperatures were about 2°C and salinities were relatively high (>34.7) except along the coast. Further off the cold East Icelandic Current ("cold tongue") showed-up to be shallow and weak both in hydrographic conditions and even extension (>0°C, ~34.7). Also the Atlantic conditions from the south on the Krossanes section were this spring weak and farther off-shore than in 1998.
Nutrient content, primary production and zooplankton concentrations were as usual depended on each other, but at different stages in different areas. The overall results indicate a relatively high productivity in Icelandic waters in spring 1999, not at least due to the pronounced nutrient rich Atlantic water including its inflow into North Icelandic waters without any low saline surface layer. At last in overall agreement with the hydrographic results no drift-ice was observed during the spring cruise 1999.
The overall results of interest for the VEINS project are the continuation of the pronounced high levels of heat and salt in the Atlantic Water mass south and west of Iceland. Compared with earlier observations, it have now in 1999 also reached North Icelandic waters and even replaced the cold and low saline surface layer which has been dominating the north since 1995. The East Icelandic Current on the other hand was observed to be shallow with temperatures above 0°C and salinities around 34.7. Finally a large overflow pulse was evident in the Faxaflói section at ca. 2000m depth of water ( figure 3a ) which according to theory can occur only if there are strong cyclonic motions above it, assuming that the pulse or dense lens is isolated and situated on a sloping bottom. Its influence on the water column above is clearly seen as downward doming of e.g. the isotherms. The overflow pulse was stratified and consisted of three layers: A 50m thick bottom layer with S~34.87 and theta~0.52°C; above a homogenous 130m salinity minimums layer with S~34.835 and theta~0.84°C, ending up with a ca. 250m thick temperature stratified layer (0.92°C< theta <2.6°C) with a salinity of ca. 34.87. Due to the relative coarse station spacing (25 km apart) it is difficult to say anything certain about dimensions of the pulse except that the diameter of the pulse must be less than 50 km and its vertical extent more than ca. 450m. The VEINS mooring section ca. 160 km downstream can perhaps give additional information on the subject. Under the assumption that the pulse travels with a mean speed of 0.3m/s it may have arrived at this VEINS mooring site around May 26th, 1999.
Preliminary TS-diagrams from the Faxaflói , Látrabjarg , Kögur , Siglunes , Langanes NE , Langanes E , Krossanes , Stokksnes and Selvogsbanki sections show the results above. In addition are preliminary potential temperature and salinity sections shown for Faxaflói (Fig. 3a and Fig. 3b), Látrabjarg (Fig. 4a and Fig. 4b), Kögur (Fig. 5a and Fig. 5b), Siglunes (Fig. 6a and Fig. 6b), Langanes NE (Fig. 7a and Fig. 7b), Langanes E (Fig. 8a and Fig. 8b), Krossanes (Fig. 9a and Fig. 9b), Stokksnes (Fig. 10a and Fig. 10b) and Selvogsbanki (Fig. 11a and Fig. 11b) sections respectively, of which Figure 3, 4, 5, 7 and 9 are part of the VEINS programme.
For location of the above sections see Figure 1 and the station numbers.
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. nameor
Tel. (+354) 55 20240
Fax. (+354) 56 23790
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| Responsible: John Mortensen | MRI | ||
