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...

Diurnal tides on the Barents Sea continental slope

“…On a diverging slope, energy going one way can "speed up"; energy going the other way might reach a point where it cannot propagate any more. This is in accordance with Kowalik and Proshutinsky (1995) who noted that diurnal period continental shelf waves were found in the proximity of strong divergence in the bathymetric field. The effect of stratification is to increase the frequency for a given wavenumber thus giving southward group velocities in the range 0-20 cm/s that could balance the mean northward current.…”

Diurnal tides on the Barents Sea continental slope

“…On a diverging slope, energy going one way can "speed up"; energy going the other way might reach a point where it cannot propagate any more. This is in accordance with Kowalik and Proshutinsky (1995) who noted that diurnal period continental shelf waves were found in the proximity of strong divergence in the bathymetric field. The effect of stratification is to increase the frequency for a given wavenumber thus giving southward group velocities in the range 0-20 cm/s that could balance the mean northward current.…”

Absolute transport estimates of total and individual water masses in the northern Greenland Sea derived from hydrographic and acoustic Doppler current profiler measurements

“…Obviously, the time varying barotropic velocities show a sinusoidal curve, which corresponds to 3 tidal cycles with maximum amplitudes of 15–20 cm s −1 . The mean velocity field is dominated by semidiurnal tides with amplitude of ∼15–20 cm s −1 corroborating the results from Kowalik and Proshutinsky [1995] showing that the semidiurnal tide M2 dominates the current regime in the vicinity of Bear Island with amplitudes of the same order. Between 1997 and 1998 Ingvaldsen et al [2002] deployed an array of five current meter moorings across the Barents Sea Opening between 71°15′N and 73°45′N.…”

A new high‐resolution unstructured grid finite volume Arctic Ocean model (AO‐FVCOM): An application for tidal studies

“…Total numbers of tide gauge and mooring stations are 297 and 416, respectively. Tide gauge data were downloaded from http://www.ims.uaf.edu/tide/ and from Kowarlik and Proshutinsky [1993Proshutinsky [ , 1994Proshutinsky [ , 1995; the current data were downloaded from http://www.mar.dfo-mpo. gc.ca/science/ocean/.…”

Diurnal tides on the Barents Sea continental slope

“…On a diverging slope, energy going one way can "speed up"; energy going the other way might reach a point where it cannot propagate any more. This is in accordance with Kowalik and Proshutinsky (1995) who noted that diurnal period continental shelf waves were found in the proximity of strong divergence in the bathymetric field. The effect of stratification is to increase the frequency for a given wavenumber thus giving southward group velocities in the range 0-20 cm/s that could balance the mean northward current.…”

Absolute transport estimates of total and individual water masses in the northern Greenland Sea derived from hydrographic and acoustic Doppler current profiler measurements

“…Obviously, the time varying barotropic velocities show a sinusoidal curve, which corresponds to 3 tidal cycles with maximum amplitudes of 15–20 cm s −1 . The mean velocity field is dominated by semidiurnal tides with amplitude of ∼15–20 cm s −1 corroborating the results from Kowalik and Proshutinsky [1995] showing that the semidiurnal tide M2 dominates the current regime in the vicinity of Bear Island with amplitudes of the same order. Between 1997 and 1998 Ingvaldsen et al [2002] deployed an array of five current meter moorings across the Barents Sea Opening between 71°15′N and 73°45′N.…”

A new high‐resolution unstructured grid finite volume Arctic Ocean model (AO‐FVCOM): An application for tidal studies

“…Total numbers of tide gauge and mooring stations are 297 and 416, respectively. Tide gauge data were downloaded from http://www.ims.uaf.edu/tide/ and from Kowarlik and Proshutinsky [1993Proshutinsky [ , 1994Proshutinsky [ , 1995; the current data were downloaded from http://www.mar.dfo-mpo. gc.ca/science/ocean/.…”

Diurnal tides on the Barents Sea continental slope

“…On a diverging slope, energy going one way can "speed up"; energy going the other way might reach a point where it cannot propagate any more. This is in accordance with Kowalik and Proshutinsky (1995) who noted that diurnal period continental shelf waves were found in the proximity of strong divergence in the bathymetric field. The effect of stratification is to increase the frequency for a given wavenumber thus giving southward group velocities in the range 0-20 cm/s that could balance the mean northward current.…”

Absolute transport estimates of total and individual water masses in the northern Greenland Sea derived from hydrographic and acoustic Doppler current profiler measurements

“…Obviously, the time varying barotropic velocities show a sinusoidal curve, which corresponds to 3 tidal cycles with maximum amplitudes of 15–20 cm s −1 . The mean velocity field is dominated by semidiurnal tides with amplitude of ∼15–20 cm s −1 corroborating the results from Kowalik and Proshutinsky [1995] showing that the semidiurnal tide M2 dominates the current regime in the vicinity of Bear Island with amplitudes of the same order. Between 1997 and 1998 Ingvaldsen et al [2002] deployed an array of five current meter moorings across the Barents Sea Opening between 71°15′N and 73°45′N.…”

A new high‐resolution unstructured grid finite volume Arctic Ocean model (AO‐FVCOM): An application for tidal studies

“…Total numbers of tide gauge and mooring stations are 297 and 416, respectively. Tide gauge data were downloaded from http://www.ims.uaf.edu/tide/ and from Kowarlik and Proshutinsky [1993Proshutinsky [ , 1994Proshutinsky [ , 1995; the current data were downloaded from http://www.mar.dfo-mpo. gc.ca/science/ocean/.…”