The Mean Sea Level Pressure (MSLP) Gradient across the Denmark Strait as Index for the Oceanographic Conditions in North Icelandic Waters

The oceanographic conditions in Icelandic waters are closely related to atmospheric forcing. In the present paper winter means of the atmospheric sea level pressure gradient across the Denmark Strait are correlated to a time series of temperature at station S3 off North Iceland. These data show that variations in North Icelandic shelf waters are closely related to the gradient. The correlation between 3-years moving averages of the gradient and the temperature at S3, one year delayed, was 0.73. This climatic relation clearly reflected the abrupt change from Atlantic to Arctic conditions on the North Icelandic shelf in the 1960s and the variability since then. Further, the effects of the variations on water mass properties in the southern Norwegian Sea are discussed. Biological effects have been observed on all levels in the food web. Various authors describe related biological variations, from the primary production level to cod and herring. The cod responded to the climatic variability and the associated narrowing habitat with a decline in abundance. The stock of herring that earlier was grazing north of Iceland, changed its migration pattern, and has not yet returned

Fisheries investigations with R.V. "G.O.Sars" in the Irminger Sea and Norwegian Sea 28 July - 21 August 1970

On the cruise R. V. «G. O. Sars» carried out an echo survey combined with trawling applying a technique described by Dragesund, Midttun and Olsen (1970). During the days 1—11 August a joint Icelandic—Norwegian survey was accomplished in the Irminger Sea and Denmark Strait. The primary aim was to investigate the distribution and abundance of 0-group fishes. Preliminary results of these investigations were presented at the ICES meeting in Copenhagen in October 1970 (Anon. 1970 a). Prior to and after the joint survey «G.O.Sars» worked in the Norwegian Sea and in the area from Iceland—Jan Mayen to Spitsbergen in order to investigate if pelagic fishes were available for commercial purposes. Scattered shoals of blue whiting where observed over a wide area exept in the northwestern part. The observed consentrations, however, were too scarce for utilizing them commercially

Changes in the Norwegian Sea deep water

This paper deals with observed changes in the Norwegian Sea Deep Water (NSDW) after the cessation of bottom water formation in the Greenland Sea. Current measurements indicate that the deep water flow from the Greenland Sea to the Norwegian Sea has reversed. The Deep Water in the Norwegian Sea is warming in the entire layer below 1000m depth and down to the bottom. The thickness of the adiabatic layer is decreasing. The salinity of the homohaline layer is constant but the thickness is decreasing. The overflow water in the Faroe-Shetland Channel is freshening

Recent upper layer cooling and freshening in the Norwegian Sea

Several time series of temperature and salinity in the Norwegian Sea indicate a general upper layer decrease in both variables. The observations indicate that this change began in about the middle of the 1960s. Time series at Ocean Weather Station "M" (OWS"M"), from Russian surveys in the southem Norwegian Sea as well as Scottish and Faroese observations in the Faroe-Shetland Channel and around the Faroes, all have similar trends and show that this is a phenomenon which affects wide areas in the Norwegian Sea. The reason for this trend is an increased supply of freshwater in the East Icelandic Current. As a result, both temperature and salinity is now at a lower level than during the "Great Salinity Anomaly'' ("GSA") in the 1970s both at 400 m depth at OWS "M" and in the 200- 500 m layer in the southem Norwegian Sea as observed in the Russian time series. The forcing may be increased production of Arctic surface water in the Greenland Sea when the deep convection is reduced, or more probably, increased export of freshwater from the Arctic Ocean. There is fairly good correlation between the wind stress curl over the Greenland Sea and the Russian time series of temperature and salinity, averaged between 200 and 500 m depth and between O and 3.5°E along 63°N in the Norwegian Sea. Considerably increased supply of Arctic Water from the East Icelandic Current during a period around 1978, clearly reinforced the "GSA" in the Nordic Seas. This also explains the coinciding variation in Atlantic and Arctic waters in the Faroe-Shetland Channel during the "GSA"

Fish survey west of the British Isles in October 1970

Områdene sør av Irland er kjente gytefelt for makrell og sild. Disse fiskestammers utbredelse og livsmønster med hensyn til eventuell utnyttelse av norske fiskere er lite kjent. Den norske ringnotflåten som opererte i området rundt Shetland sist sommer, var i kontakt med forekomster av makrell som ikke tilhørte makrellstammen i Nordsjøen. Disse forekomstene var delvis oppblandet med stor taggmakrell som er vanlig å finne i området vest av Irland. Dette kan således indikere hvilket område disse blandete forekomstene stammer fra. Ved Hebridene finnes det videre en høstgytende sildestamme som delvis har vært beskattet av den norske ringnotflåten i Shetlandsområdet i sommerhalvåret. I tiden 4.—20. oktober ble det med F/F «G. O. Sars» foretatt en undersøkelse av området vest av De Britiske Øyer. Hensikten var å undersøke muligheten for utnyttelse av de makrell- og sildeforekomster som måtte finnes i området på denne årstid og å undersøke hvorvidt det fantes andre fiskearter som kunne danne grunnlag for kommersiell drift. Det avsøkte området fremgår av Fig, 1. Den tekniske stab på roktet besto av O.Chruickshank, P, Eide, H. Gill, J. Klæt, W. Løtvedt, S. Myklevoll, og A. Storler. «G. O. Sars» ble ført av A. Lunde

Blue whiting investigations in the Norwegian Sea and northwest of the British Isles in January - February 1973

Blue whiting investigations were carried out at the Møre— Helgeland plateau and in the Faero—Shetland areas during the period 8 January to 9 February. Most of the blue whiting were localized in the Faero— Shetland area. The best consentrations were found in the transition layers between the Atlantic water masses and the colder masses below and beside. The fish was here in a prespawning state and was probably mowing towards the spawning locality. An acoustic abundance estimate of the recorded blue whiting in this area gave a total 15 x 10\6 hl