Diurnal tides near the Yermak Plateau

Recent current measurements obtained from drifting platforms over the Yermak Plateau in the eastern Arctic Ocean confirm that the plateau is a region of greatly enhanced diurnal tidal currents. Modulation of the diurnal currents is clearly related to the plateau topography, as has been previously proposed. We show, however, that temporal variability due to spring-neap modulation must also be considered in interpreting records from drifting platforms. We review simple models of tidal current amplification in this region and find that the previous assumption of near-resonant, barotropic shelf waves propagating around the plateau's entire perimeter is inconsistent with the true topography. Instead, we propose that the diurnal variability is due to topographic shelf waves at the K1 and O1 tidal frequencies that are generated at points on the plateau's perimeter where the waves' group velocities are near zero. Observed cross-slope variations in ellipticity, orientation, and magnitude of tidal oscillations are consistent with the presence of topographic waves generated in this manner. The topographic enhancement of the diurnal tide near the Yermak Plateau has important consequences for the sea ice cover, hydrography, and general circulation of this region. For example, the stress divergence applied by the tidal currents at the ice base greatly exceeds the typical divergence of the surface wind stress, and tides may therefore be important to local ice deformation. The strong cross-slope tidal currents also appear to be responsible for the production of high-frequency internal wave packets, which are associated with energetic diapycnal mixing in the pycnocline. We also consider the possibility that tidal rectification is responsible for a mean current transporting Atlantic Water clockwise around the plateau.

[1]  E. D’Asaro,et al.  Internal waves and mixing in the Arctic Ocean , 1992 .

[2]  A. Plueddemann.  Internal wave observations from the Arctic environmental drifting buoy , 1992 .

[3]  Robert Pinkel,et al.  Repeat-Sequence Coding for Improved Precision of Doppler Sonar and Sodar , 1992 .

[4]  C. Paulson,et al.  Winter oceanographic conditions in the Fram Strait‐Yermak Plateau region , 1992 .

[5]  D. Menemenlis,et al.  Ice Flexure Forced by Internal Wave Packets in the Arctic Ocean , 1991, Science.

[6]  Christophe Prazuck.  Anomalous Diurnal Currents in the Vicinity of the Yermak Plateau , 1991 .

[7]  T. Dillon,et al.  Turbulent mixing near the Yermak Plateau during the Coordinated Eastern Arctic Experiment , 1991 .

[8]  Paul Hoffman.  Transpolar Sea Ice Drift in the Vicinity of the Yermak Plateau as Observed by ARCTEMIZ 86 Buoys , 1990 .

[9]  M. Gregg,et al.  Scaling turbulent dissipation in the thermocline , 1989 .

[10]  D. Chapman.  Enhanced subinertial diurnal tides over isolated topographic features , 1989 .

[11]  M. Mcphee.  Analysis and Prediction of Short-Term Ice Drift , 1988 .

[12]  T. Dillon,et al.  Vertical heat fluxes through the Beaufort Sea thermohaline staircase , 1987 .

[13]  J. Morison,et al.  Boundary layer, upper ocean, and ice observations in the Greenland Sea Marginal Ice Zone , 1987 .

[14]  T. Foster,et al.  Diurnal Shelf Waves in the Southern Weddell Sea , 1987 .

[15]  M. Gregg,et al.  Diapycnal mixing in the thermocline: A review , 1987 .

[16]  K. Hunkins.  Anomalous diurnal tidal currents on the Yermak Plateau , 1986 .

[17]  K. Brink,et al.  Programs for computing properties of coastal-trapped waves and wind-driven motions over the continental shelf and slope , 1985 .

[18]  E. Lewis,et al.  Mixing in the West Spitsbergen Current , 1984 .

[19]  G. Johnson,et al.  The Yermak Plateau: Formed at a triple junction , 1984 .

[20]  K. Aagaard,et al.  One-year records of current and bottom pressure in the strait between Nordaustlandet and Kvitøya, Svalbard, 1980-81 , 1983 .

[21]  E. Lewis,et al.  Supercooling and energy exchange near the Arctic Ocean surface , 1983 .

[22]  L. Johnson.  The FRAM expeditions: Arctic Ocean studies from floating ice, 1979–82 , 1983, Polar Record.

[23]  D. Chapman,et al.  Shelf wave dispersion in a geophysical ocean , 1982 .

[24]  W. Crawford,et al.  The Generation of Diurnal Period Shelf Waves by Tidal Currents , 1982 .

[25]  J. Loder.  Topographic Rectification of Tidal Currents on the Sides of Georges Bank , 1980 .

[26]  E. W. Schwiderski,et al.  On charting global ocean tides , 1980 .

[27]  O. Johannessen.  Note on Some Vertical Profiles below Ice Floes in the Gulf of , 1970 .

[28]  T. Straume,et al.  Model simulations of the M2and the K1tide in the Nordic Seas and the Arctic Ocean , 1989 .

[29]  T. Straume,et al.  Model simulations of the M2 and the K1 tide in the Nordic Seas and the Arctic Ocean , 1989 .

[30]  K. Hunkins.  Current and Temperature Data from Instrument Moorings in Fram Strait during MIZEX 83. , 1984 .

[31]  J. Huthnance.  Large tidal currents near Bear Island and related tidal energy losses from the North Atlantic , 1981 .