Internal wave generation by ice floes moving in stratified water: Results from a laboratory study

Waters, Jennifer K.; Bruno, Michael S.

doi:10.1029/95jc01220

Cited by 8 publications

(5 citation statements)

References 7 publications

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“…It is well known that a layer of fresh water on top of more saline water can cause so‐called dead water [ Ekman , ], where internal waves form at the bottom of the fresh water layer, increasing the drag felt at the ocean surface. Waters and Bruno [] showed that introducing such a fresh water layer may cause as much as a fivefold increase of the ice‐ocean drag. If we could include this effect in the normalization of the ice drift speed, we would expect to see higher normalized drift speeds at the peak of the melt season.…”

Section: Seasonal Cycle Of Drift Speedmentioning

confidence: 99%

Drivers of variability in Arctic sea‐ice drift speed

Ólason

Notz

2014

JGR Oceans

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We explore the main drivers of seasonal and long-term variations in basin-scale Arctic sea-ice drift speed. To do so, we examine the relationship between the observed time-varying area-mean ice drift speed in the central Arctic and observed thickness and concentration as well as surface wind stress. Drift speeds are calculated from the positions of drifting buoys, thickness is based on submarine observations, concentration on satellite observations, and the wind stress comes from a global reanalysis. We find that seasonal changes in drift speed are correlated primarily with changes in concentration when concentration is low and with changes in thickness otherwise. The correlation between drift speed and concentration occurs because changing concentration changes how readily the ice responds to the synoptic-scale forcing of the atmosphere. Drift speed is correlated with neither concentration nor thickness in April and May. We show this behavior to be correlated with a decrease in the localization of deformation. This indicates that the increase in drift speed is caused by newly formed fractures not refreezing, leading to an overall reduced ice-cover strength without a detectable change in ice concentration. We show that a strong long-term trend exists in months of relatively low ice concentration. Using our analysis of the seasonal cycle, we show that the trend in concentration drives a significant portion of the drift-speed trend, possibly reinforced by a trend in cyclone activity. Hence, the trend in drift speed in this period is primarily caused by increased synoptic-scale movement of the ice pack.

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Section: Seasonal Cycle Of Drift Speedmentioning

confidence: 99%

Drivers of variability in Arctic sea‐ice drift speed

Ólason

Notz

2014

JGR Oceans

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“…Modern parameterizations [5,12] of the drag coefficient, both in sea ice dynamics models and iceberg drift prediction models [13], do not explicitly incorporate the effects of the ocean stratifi cation. The distribution of internal waves in such sys tems (provided the comparability of the depth of the underwater part of the hummocked ice and the thick ness of the mixed layer) can alter the ice drag force, which is confirmed by observations [14][15][16] and labo ratory experiments [17,18]. Measurements show that the increase in the drag force is most pronounced in the presence of a shallow and strong pycnocline, whose stability is supported by the ice melting.…”

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confidence: 62%

Numerical simulation of the motion of an ice keel in a stratified flow

Mortikov

2016

Izv. Atmos. Ocean. Phys.

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The results of the three dimensional numerical simulation for the study of the stratification effect and wave processes associated with it on the drag of the underwater part of the hummocked ice are consid ered. The numerical model is based on the sampling of equations on a rectangular grid using the immersed boundary method that makes it possible to explicitly describe the interaction of moving ice with a stratified flow. The dependence of the drag force on the Froude number was established based on these calculations. This dependence has expressed points of maximum and minimum. The form of this dependence is common for the considered models of ice keels. The obtained estimations of drag force consistent with the known results of laboratory experiments show the need for the construction of parametrizations of the drag coeffi cient on the ice-ocean boundary, taking into account wave effects.

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“…Although the sea surface anomalies are different between these two cases, the generation mechanisms of internal lee waves are essentially the same. A similar generation mechanism of internal lee waves is thought to work under the moving sea ice driven by the wind [e.g., Muench et al ., ; McPhee and Kantha , ; Waters and Bruno , ].…”

Section: Summary and Discussionmentioning

confidence: 99%

Downward lee wave radiation from tropical instability waves in the central equatorial Pacific Ocean: A possible energy pathway to turbulent mixing

Tanaka

Hibiya

Sasaki³

2015

JGR Oceans

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Turbulent mixing in the equatorial Pacific Ocean is an important process that controls diapycnal heat transport and hence affects the air‐sea interactions and global climate. It is recently shown that, in the eastern equatorial Pacific, strong mixing is induced in the thermocline by enhanced vertical shear associated with tropical instability waves (TIWs), which propagate westward along the equator at a speed of ∼0.5 m normals−1 with a wavelength of ∼1000 km. In this study, using a high‐resolution ocean general circulation model, we show that the TIWs can play an important role in inducing turbulent mixing in the thermocline also in the central equatorial Pacific, although the thermocline is too deep to be directly affected by the vertical shear of the TIWs. The front of the TIW is clearly manifested as a narrow strip of strong convergence of horizontal surface flow, from which area downward and westward propagating internal waves are intermittently emanated. These internal waves can be interpreted as lee waves generated by the surface‐flow convergence zone, which acts like an inverted obstacle moving along the stratified ocean surface by inducing downward flow. The associated downward energy flux below the surface mixed layer increases as the TIW structure becomes deeper toward the central equatorial Pacific, so that the energy pathway to turbulent mixing in the thermocline can be created. The downward energy flux integrated over the entire equatorial Pacific and averaged during January 2011 amounts to ∼8.1 GW, occupying a significant fraction of the energy input to the TIWs.

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Internal wave generation by ice floes moving in stratified water: Results from a laboratory study

Cited by 8 publications

References 7 publications

Drivers of variability in Arctic sea‐ice drift speed

Drivers of variability in Arctic sea‐ice drift speed

Numerical simulation of the motion of an ice keel in a stratified flow

Downward lee wave radiation from tropical instability waves in the central equatorial Pacific Ocean: A possible energy pathway to turbulent mixing

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