Physical Oceanography in the Arctic Ocean: 1968

The support of drifting stations and other scientific work on the pack ice by the Naval Arctic Research Laboratory is basic for the US studies of the central Arctic Ocean. A synoptic picture of temperature/salinity variables is needed, as is information on spatial variations of the currents. During the summer 1967, the satellite navigation system gave fixes of Fletcher's Ice Island T-3, from which water motion at depths of 150, 500 and 1300 m was recorded. Results of analyses are graphically shown and discussed; the technique used to smooth the track, noted. The flow is similar in the three water masses; a long-term period variation in the record probably represents the T-3 motion; there is a marked oscillation of ~semidiurnal period which undoubtedly represents an inertial or semidiurnal tidal oscillation. Tracks of drifting stations during 20 yr define the Beaufort gyre circulation, the center of which, 80 W, 140 W, coincides with that of a mean atmospheric pressure anticyclone. West of 140 W, the dominant W and N drifts are segments in the Transpolar Drift Stream; east of 140 W, where drifts are mainly E to W, they are in the eastern Beaufort gyre. Ice drifts faster in the Transpolar Stream than along the Canadian Islands by about 1/2 nautical mi/day; a marked increase in speed occurs in summer or fall; the atmospheric pressure gradient variations agree qualitatively with the drift speed variations. Three experiments needed to solve the principal remaining problems are explained

Currents in Long Strait, Arctic Ocean

Reports and discusses current measurements made Aug 1966 from USS Burton Island (AGB-1) in the strait which separates Vrangelya Island from the Siberian mainland. A significant tidal oscillation of the currents is caused by the semidiurnal tide wave of the Arctic Ocean, propagating eastward through the strait. The oscillation varies in amplitude with the semimonthly tidal inequality. The long-term mean flow through the channel appears to be controlled by continuity requirements of the Chukchi Sea - East Siberian Sea systems as it responds to the regional winds. When regional atmospheric pressure gradients dictate winds E of Vrangelya and/or northerly-southerly winds to the west, the flow is west-bound through the strait, and vice versa. The surface layer and ice field respond more directly to local winds.Les courants dans le détroit de Long, océan Arctique. Au cours de l'été de 1966, on a recueilli dans le détroit de Long, qui sépare l'île Wrangel de la Sibérie continentale, environ 440 mesures des courants. Cette suite de données actuelles est la plus complète dont on dispose pour la région et elle fournit une information très utile sur la nature et la genèse des courants. L'onde semi-quotidienne de marée de l'Arctique provoque, en se propageant vers l'Est à travers le détroit, une importante oscillation des courants, surtout dans l'axe du chenal. Cette oscillation varie en amplitude selon l'inégalité tidale semi-mensuelle. A long terme, le flux moyen dans le détroit est déterminé par la demande de continuité du système : mer de Tchoukotsk-mer de Sibérie orientale en correspondance avec les vents régionaux. Lorsque les différences régionales de la pression atmosphérique provoquent des vents du sud à l'Est de l'île Wrangel et/ou des vents du nord à l'Ouest de cette île, il se produit un flux vers l'ouest du détroit, et vice-versa. La couche d'eau de surface et le champ de glace sont plus directement sensibles aux vents locaux

A Note on Ice Island WH-5

As reported by Hattersley-Smith, Ice Island WH-5, the easternmost and largest (approximately 20 by 9 km.) of the islands resulting from the massive calving of the Ward Hunt Ice Shelf during the winter 1961-2, drifted eastward, whereas the other four islands drifted westward. WH-5, tracked through radar photography by the U.S. Navy "Birdseye" ice reconnaissance flights, continued its eastward movement during the winter 1962-3. It entered the Lincoln Sea, moved south through Robeson Channel and between February 24 and 28, 1963 became lodged across Kennedy Channel, with one end resting against the shore of Ellesmere Island and the other end held by mid-channel Hans Island. In this position the ice island formed an effective barrier to the southward movement of sea-ice from the Arctic Ocean. Open water soon appeared south of the obstruction and by May extended well into Kane Basin. In a study of WH-5 during the summer of 1963 emphasis was placed on physical oceanography, both to observe the local influence of the ice island and to take advantage of the unusual presence of open water in an area where ice normally restricts ship operations. The study was directed by D. C. Nutt and L. K. Coachman and was sponsored by the Arctic Institute with support from the U.S. Office of Naval Research and the U.S. Coast Guard and the collaboration of the Woods Hole Oceanographic Institution, the U.S. Naval Oceanographic Office, the U.S. Military Sea Transportation Service and the U.S. Air Force at Thule, Greenland. ... This brief note, based only on data immediately available, is being published to provide timely information on the recent drift and break-up of ice island WH-5. A more comprehensive report will follow. ..

The Movement of Atlantic Water in the Arctic Ocean

Re-evaluates sixty years' oceanographic data from the Arctic Ocean, examining nearly 300 deep-water stations, and using the "core-layer" method of Wust to interpret the movement of the Atlantic layer. Stations are grouped in 16 areas and the average curve for each group plotted on a temperature-salinity diagram. Temperature and salinity changes which take place in the Atlantic water while and entity in the Arctic Basin are graphed. The temperature maximum is reduced by about 3.5 C, and the salinity at max. temperature is reduced by about 0.2 %. Superimposed on the T-S relationship is an arbitrary scale indicating percentage retention of the original characteristics. The velocity of the Atlantic layer is found (from current velocity, eddy coefficients and station data) to range 1-10 cm/sec and values of Kz (vertical eddy coefficient) generally to range 1-20 sq cm/sec. Percentage retention of characteristics from the T-S diagram is mapped to suggest a relation between the flow of Atlantic water and bathymetry, distance, time, as well as the T-S features. Assuming the velocity along the core to be 3 cm/sec, the constant vertical eddy coefficient to be 10 sq cm/sec, and with other assumptions on temperature distribution, an estimate of 8,000,000 sq cm/sec is obtained for the constant lateral eddy coefficient

The East Greenland Current North of Denmark Strait: Part II

Deals primarily with data from cruises of the Edisto, summers 1964-65, and 1965 drift of Arlis II; supported by the Office of Naval Research through the Arctic Institute of North America. Pt 2 gives more detailed data on the temperature/salinity distributions and movements of the polar water, which represents only a minor part of the total flow, but constitutes the upper layer of the East Greenland Current and mainly controls the ice distribution; the Atlantic intermediate water, the major component of the total transport, warmer than the other waters, whose westward movement from the West Spitsbergen current begins just north of 75 N, occurs over a wide range of latitude, probably to 80 N, with the depth of the layer decreasing westward. At about 73 N, warm water moves eastward in a cyclonic movement presumably associated with that of the polar water in the Jan Mayen Polar Current; warm water not involved in this movement continues southward near the continental slope at >200 m depths. The deep water (below 1500 m) underlying the Norwegian Sea gyre (S and SE of Jan Mayen) and Greenland Sea gyre (NE of Jan Mayen) can be differentiated by temperature, the one always warmer than -1C, the other always colder. The deep water along the Greenland slope is either the Norwegian Sea or the transitional type; that of the Polar basin comes primarily from the Norwegian Sea.Le courant de l'est du Groenland, au nord du Détroit de Danemark. Deuxième partie. Des mesures directes de courant et des études de distribution des températures dans la mer du Groenland indiquent que, si les eaux polaires du courant de l'Est du Groenland tirent leur origine de l'océan Arctique, la masse des eaux intermédiaires et profondes circule de façon cyclonique. Il y a des changements saisonniers systématiques dans la température et la salinité des eaux polaires. Ces changements sont liés au cycle annuel de formation et de fonte de la glace, et sont conditionnés par l'advection horizontale, la diffusion turbulente verticale et, en hiver, par la convection pénétrative. En été, il existe une tendance baroclinique prononcée qui devrait se manifester par une réduction de la vitesse du courant en fonction de la profondeur. Cependant, des mesures directes de courant au cours de l'hiver montrent que cette variation n'existe pas. La cause le plus probable de cette anomalie est que l'importance relative de la contribution baroclinique au gradient de pression varie selon la saison. On a observé à toutes les profondeurs du courant de l'Est du Groenland des déplacements latéraux des masses d'eau de 70 km ou plus en quelques jours, ce qui suggère comme cause première une perturbation barotropique à grande échelle

The Contribution of Bering Sea Water to the Arctic Ocean

Summarizes the characteristics, especially temperature-salinity of these waters as they flow north through Bering Strait, and as they modify the surface water, deeper water, and ice cover of the western Arctic Ocean. Analysis of about 200 deep-water stations reveals regularity in the vertical distribution of temperature and salinity. The shallow 75-100 m depth, temperature maximum observed in the western as distinct from the eastern Arctic Basin is maintained by advection from some external source, in part the flow through the Strait. Bering Sea water apparently flows north into Chukchi Sea, where it mixes with Siberian shelf water then joins the general circulation in the area northwest of Point Barrow. The intruding Bering Sea water separates deeper Atlantic water from Arctic Ocean surface water; this Bering water may be traced by the shallow temperature maximum; but it affects ice conditions in the Basin very little

Surface Water in the Eurasian Basin of the Arctic Ocean

Reports results of re-appraisal and interpretation of data from 74 oceanographic stations (of >400 occupied), listed according to vessel and source. Surface water occupies the uppermost 200 m It is almost continuously supplied by continental runoff from Siberia which mixes with and collects saline water, to a few hundred times its original volume, as it crosses the arctic shelf seas. The surface water then flows directly to the exit from the basin between Spitsbergen and Greenland. Three layers of surface water are distinguished, on the basis of temperature and salinity features. Variations and ranges within each layer are thought the result of geographic location, presence of ice cover, seasonal changes, convection , and advection. Lowest layer, from 100 m down to the Atlantic water, shows evidence of mixing with the subsurface layer, as well as evidence of continuous replenishment. Prevalence of the cold subsurface layer in this basin is explained by a proposed model, which recognizes the submarine canyons, notably the Svyataya Anna in the Kara Sea, as important factors in mixing and cooling and as primary sources of subsurface water

Atlantic Water Circulation in the Canada Basin

Circulation of the Atlantic water layer in the Canada Basin of the Arctic Ocean is re-examined using the numerous data acquired in the last decade. Methods of analysis were (1) the core layer method as used ten years previously, (2) a 500/1000-decibar dynamic topography, and (3) the available direct current measurements. The results confirm the general anti-cyclonic circulation deduced previously which has a transport of about 0.6 sverdrups. A new feature is described: a sub-surface counterflow moving southeast along the eastern slope of the Chukchi Rise with a transport of about 0.3 sverdrups

The East Greenland Current North of Denmark Strait: Part I

Deals primarily with data from cruises of the Edisto, summers 1964-65, and 1965 drift of Arlis II; supported by the Office of Naval Research through the Arctic Institute of North America. Pt 1 summarizes previously published papers on the East Greenland Current, notes some bathymetric features of the western Greenland Sea and its water masses, and discusses general features of the velocity field, mean velocities and volume transports of the current.Le courant du Groenland oriental au nord du détroit de Danemark. Au cours de l'hiver de 1965, des mesures effectuées dans le courant du Groenland oriental ont montré que sur le talus continental, la circulation comporte d'importantes composantes dirigées vers le rivage, ce qui représente probablement un flux vers l'ouest selon le mouvement d'Ekman. La vitesse ne diminue pas beaucoup avec la profondeur, ce qui indique que le mode barotropique domine la circulation. Les vitesses typiques du courant sont de 10 à 15 cm/s‾¹.Au cours de l'hiver, le débit du courant dépasse 35 x 10⁶ m³/s‾¹. Cet ordre de grandeur dépasse les anciennes estimations et, malgré les fluctuations saisonnières possibles, il semble que le courant du Groenland oriental correspond surtout à une circulation interne des mers du Groenland et de Norvège, plutôt qu'à un émissaire du bassin polaire central