Topographic enhancement of tidal motion in the western Barents Sea

Abstract

Abate-notA hi•h-roe•l,,fi•n n,,mori,-nl l•**ice is used to study a topographically trapped motion around islands and shallow banks of the western Barents Sea caused both by the semidiurnal and diurnal tidal waves. Observations and model computations in the vicinity of Bear Island show well-developed trapped motion with distinctive tidal oscillatory motion. Numerical investigations demonstrate that one source of the trapped motion is tidal current rectification over shallow topography. Tidal motion supports residual currents of the order of 8 cm s -1 around Bear Island and shallow Spitsbergenbanken. The structures of enhanced tidal currents for the semidiurnal components are generated in the shallow areas due to topographic amplification. In the diurnal band of oscillations the maximum current is associated with the shelf wave occurrence. Residual currents due to diurnal tides occur at both the shallow areas and the shelf slope in regions of maximum topographic gradients. Surface manifestation of the diurnal current enhancement is the local maximum of tidal amplitude at the shelf break of the order of 5 to 10 cm. Tidal current enhancement and tidally generated residual currents in the Bear Island and Spitsbergenbanken regions cause an increased generation of ice leads, ridges and, trapped motion of the ice floes. OscillaLory and residual Lidal currenLs in Lhe BI area are imporLant because •his island is located close to •he deep Norwegian Sea. Heal and salL, enLering into •he shallow waLer around Lhe BI and shallow banks, are modified Lhrough Lhe tidal motion. Residual tidal motion calculated from an 18-km grid model for •he shallow areas souLh of Spitsbergen depicts small velocity of the order of 1 cm s -• [IIarm•, 19912]. It exactly delinea.•es polar fron• location and •herefore can influ-,,' ß ß ß , , ß 100---"" o, KOWALIK AND PROSHUTINSKY: ENHANCEMENT OF TIDAL MOTION culations demonstrate that in the vicinity of BI the polar front can be generated and maintained not only by the inflow of the warm Atlantic waters and outflow of the cold Arctic waters, but also by the tidal motion. Shelf Res., 10, 81-86, 1990. Pca.se, C. H., P. Turet, R. S. Pritchard, and J. E. Overland, Barents Sea tidal, wind drift, and inertial motion from ARGOS ice buoys during CEAREX, J. Geophys. Res., in press, 1995. Pingtee, R. D., and L. Maddock, Rotary currents and residual circulation around banks and islands, Deep Sea Res., Part A, 32, 929-947, 1985. Pingtee, R. D., P.M. Holligan, and G. T. Mardell, The effect of vertical stability on phytoplankton distributions in the summer on the northwest European shelf, Deep Sea Res., Part A, 25, 1011-1028, 1978. Proshutinsky, A. Yu., Tidal water and ice dynamics in the rents in the western Dutch Wadden Sea, in Coastal and Estuarine Studies, edited by R. T. Cheng, pp. 93-104, Springer-Verlag, New York, 1990. Robinson, I.S., Tidal vorticity and residual circulation, Deep Sea Res., part A, 28, 195-212, 1981. Sandven, S., and O. M. Johannessen, The use of microwave remote sensing for sea ice studies...

Macrozooplankton communities and environmental variables in the Barents Sea marginal ice zone in late winter and spring

“…The latitudinal gradient was generally in good agreement with the salinity and temperature gradients, but exceptions were found because of the deep inflow of AtW between Nordaustlandet and Franz Josef Land and the strong impact of the bottom topography (Loeng 1991, Løyning 2000. Generally, ArW occurs in the bank areas in the northern Barents Sea, but over the shelf breaks (slopes) strong tidal currents force the heavier AtW up and onto the banks (Loeng 1991, Kowalik & Proshutinsky 1995. This transport is particularly apparent over shallow banks (Kowalik & Proshutinsky 1995), which explains the dominance of MIX over the shallow Spitsbergen Bank (Stns B4 and B5), relatively far from the shelf break (Fig.…”

“…Generally, ArW occurs in the bank areas in the northern Barents Sea, but over the shelf breaks (slopes) strong tidal currents force the heavier AtW up and onto the banks (Loeng 1991, Kowalik & Proshutinsky 1995. This transport is particularly apparent over shallow banks (Kowalik & Proshutinsky 1995), which explains the dominance of MIX over the shallow Spitsbergen Bank (Stns B4 and B5), relatively far from the shelf break (Fig. 2).…”

Water mass distribution and Polar Front structure in the Southwestern Barents Sea

“…Tidal velocities up to 100 cm/s west of Bjornoya on Spitzbergen Bank have been predicted by a model [Kowalik and Proshutinsky, 1995]. The shallow Spitzbergen Bank and strong tidal forcing produce a tidal mixing front whose location coincides with the 100 m isobath to the south and west of Bjornoya.…”

The West Spitsbergen Current volume and heat transport from synoptic observations in summer

“…Current profiles were corrected for tidal motions by subtracting the vertically homogenous tide component. For every LADCP cast, K1, O1, M2, and S2 tidal components were calculated using amplitudes and phases of tidal velocity components U and V given by Kowalik (1994) and Kowalik and Proshutinsky (1995). The tidal data are available via anonymous ftp: ftp.ims.uaf.edu.…”