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Tabular icebergs in ocean waves
754
A. Physical Oceanography
With a 2-layer stratified fluid model, internal-wave absorption (instability) value is dependent on the 'critical layer' in which wave-phase and current velocities approximate each other. Temporal evolution of the waves is discussed. (isz) 82:5933 Sabinin, K.D., A.A. Nazarov and A.N. Serikov, 1982. Connection of short-period internal wave trains with relief of the thermocline in the ocean. Fiz. Atmoff. Okeana, 18(4):416-425. (In Russian, English abstract.)
Direct measurements showed short internal waves propagating up the thermocline slope; nonlinear and refraction effects and the generation of short-wave trains were similar to those observed when internal tide waves break in shallow water. (sir) 82:5934 Segur, Harvey and J.L. Hammack, 1982. Soliton models of long internal waves. J. Fluid Mech., 118:285-304.
The Korteweg-de Vries (KdV) equation and the finite-depth equation of Joseph (1977) and Kubota, Ko & Dobbs (1978), describing the evolution of long internal waves of small but finite amplitude, are tested experimentally by comparing measured and theoretical soliton shapes. The KdV equation predicts soliton shapes with remarkable accuracy; when carried to second-order, the finite-depth theory becomes about as accurate as (first-order) KdV theory. However, second-order corrections to the finite-depth theory also identify a bound on its range of validity which turns out to be rather small; it includes only about half of the experiments reported by Koop & Butler (1981). Aeronautical Res. Assoc. of Princeton, Inc., P.O. Box 2229, Princeton, N.J. 08540, USA.
A210. Ice 82:5935 de Lange Boom, B.R., M.R. MacNeill and J.R. Buckley, 1982. Iceberg motion in Lancaster Sound and northwest Baffln Bay, summer 1978. Arctic, 35(1):219-233. Seakem Oceanogr. Ltd., 2045 Mills Rd., Sidney, BC V8L 3S1, Canada. 82:5936 Haggblom, Anders, 1982. Driftwood in Svalbard as an indicator of sea ice conditions. Geogr. Annlr, (A)64(1/2):81-94. Dept. of Phys. Geogr., Univ. of Stockholm, Sweden.
OLR (1982) 29112)
82:5937 Kristensen, Monica, V.A. Squire and S.C. Moore, 1982. Tabular icebergs in ocean waves. Nature, Lond., 297(5868):669-671.
Ocean waves are a principal agent in the deterioration and ultimate breakup of Antarctic tabular icebergs in the Southern Ocean. Data show that icebergs tend to act as low-pass filters and inhibit short period waves. Furthermore, they selectively resonate at certain wave periods; strain data indicate unexpectedly large flexure which cannot be explained by simple bending alone. The geometry of icebergs can be such as to render them unstable and liable to turn over. Scott Polar Res. Inst., Univ. of Cambridge, Cambridge CB2 1ER, UK. 82:5938 Lepparanta, Matti, 198l. On the structure and mechanics of pack ice in the Bothnian Bay. Finn. mar. Res., 248:3-86.
Bothnian Bay pack ice in March and April is fractured into separate floes of diameters from tens of meters to 4-5 km; thickness of level ice is ~J/2 m. Ice drift follows the wind with a response time shorter than 1 hr; governing forces are the surface shear stresses of wind and water on ice and internal friction in the ice. Largest viscosities result when compactness is highest simultaneously with either small deformation rates or ice ridging. Kinetic energy dissipation in internal deformation processes is significant, and the main energy sinks are the shearing friction between floes and potential energy production in ridges; the former is several times the latter. Inst. of Mar. Res., P.O. Box 166, SF-00141 Helsinki 14, Finland. 82:5939 Marko, J.R., J.R. Birch and M.A. Wilson, 1982. A study of long-term satellite-tracked iceberg drifts in Baffin Bay and Davis Strait. Arctic, 35(1):234240.
Iceberg trajectories were analyzed relative to the larger spatial and temporal scales of iceberg drift. Berg movements were concentrated in the core of the southward-flowing Baffin Current. Net rate of southward movements was governed by a combination of grounding and landfast ice entrapment --particularly significant in areas of the coastal shelf adjacent to major submarine canyon systems. Arctic Sci. Ltd., 1986 Mills Rd., R.R. 2, Sidney, BC V8L 3S1, Canada. 82:5940 Oerlemans, J., 1982. A model of the Antarctic Ice Sheet. Nature, Lond., 297(5867):550-553.
A. Physical Oceanography
With a 2-layer stratified fluid model, internal-wave absorption (instability) value is dependent on the 'critical layer' in which wave-phase and current velocities approximate each other. Temporal evolution of the waves is discussed. (isz) 82:5933 Sabinin, K.D., A.A. Nazarov and A.N. Serikov, 1982. Connection of short-period internal wave trains with relief of the thermocline in the ocean. Fiz. Atmoff. Okeana, 18(4):416-425. (In Russian, English abstract.)
Direct measurements showed short internal waves propagating up the thermocline slope; nonlinear and refraction effects and the generation of short-wave trains were similar to those observed when internal tide waves break in shallow water. (sir) 82:5934 Segur, Harvey and J.L. Hammack, 1982. Soliton models of long internal waves. J. Fluid Mech., 118:285-304.
The Korteweg-de Vries (KdV) equation and the finite-depth equation of Joseph (1977) and Kubota, Ko & Dobbs (1978), describing the evolution of long internal waves of small but finite amplitude, are tested experimentally by comparing measured and theoretical soliton shapes. The KdV equation predicts soliton shapes with remarkable accuracy; when carried to second-order, the finite-depth theory becomes about as accurate as (first-order) KdV theory. However, second-order corrections to the finite-depth theory also identify a bound on its range of validity which turns out to be rather small; it includes only about half of the experiments reported by Koop & Butler (1981). Aeronautical Res. Assoc. of Princeton, Inc., P.O. Box 2229, Princeton, N.J. 08540, USA.
A210. Ice 82:5935 de Lange Boom, B.R., M.R. MacNeill and J.R. Buckley, 1982. Iceberg motion in Lancaster Sound and northwest Baffln Bay, summer 1978. Arctic, 35(1):219-233. Seakem Oceanogr. Ltd., 2045 Mills Rd., Sidney, BC V8L 3S1, Canada. 82:5936 Haggblom, Anders, 1982. Driftwood in Svalbard as an indicator of sea ice conditions. Geogr. Annlr, (A)64(1/2):81-94. Dept. of Phys. Geogr., Univ. of Stockholm, Sweden.
OLR (1982) 29112)
82:5937 Kristensen, Monica, V.A. Squire and S.C. Moore, 1982. Tabular icebergs in ocean waves. Nature, Lond., 297(5868):669-671.
Ocean waves are a principal agent in the deterioration and ultimate breakup of Antarctic tabular icebergs in the Southern Ocean. Data show that icebergs tend to act as low-pass filters and inhibit short period waves. Furthermore, they selectively resonate at certain wave periods; strain data indicate unexpectedly large flexure which cannot be explained by simple bending alone. The geometry of icebergs can be such as to render them unstable and liable to turn over. Scott Polar Res. Inst., Univ. of Cambridge, Cambridge CB2 1ER, UK. 82:5938 Lepparanta, Matti, 198l. On the structure and mechanics of pack ice in the Bothnian Bay. Finn. mar. Res., 248:3-86.
Bothnian Bay pack ice in March and April is fractured into separate floes of diameters from tens of meters to 4-5 km; thickness of level ice is ~J/2 m. Ice drift follows the wind with a response time shorter than 1 hr; governing forces are the surface shear stresses of wind and water on ice and internal friction in the ice. Largest viscosities result when compactness is highest simultaneously with either small deformation rates or ice ridging. Kinetic energy dissipation in internal deformation processes is significant, and the main energy sinks are the shearing friction between floes and potential energy production in ridges; the former is several times the latter. Inst. of Mar. Res., P.O. Box 166, SF-00141 Helsinki 14, Finland. 82:5939 Marko, J.R., J.R. Birch and M.A. Wilson, 1982. A study of long-term satellite-tracked iceberg drifts in Baffin Bay and Davis Strait. Arctic, 35(1):234240.
Iceberg trajectories were analyzed relative to the larger spatial and temporal scales of iceberg drift. Berg movements were concentrated in the core of the southward-flowing Baffin Current. Net rate of southward movements was governed by a combination of grounding and landfast ice entrapment --particularly significant in areas of the coastal shelf adjacent to major submarine canyon systems. Arctic Sci. Ltd., 1986 Mills Rd., R.R. 2, Sidney, BC V8L 3S1, Canada. 82:5940 Oerlemans, J., 1982. A model of the Antarctic Ice Sheet. Nature, Lond., 297(5867):550-553.