waves due to IW, thus providing a mechanism for internal waves to be manifested
at the surface. Hydrodynamic contrast was defined as M(k) = N1/N0, where N0 is
the spectral action density of an undisturbed surface wave spectrum, and N1 corresponds to the perturbations in the spectral action density due to the horizontal
surface currents induced by IW. Bondur et al. [11] solved the spectral action
balance equation [30], using the estimates of IW parameters for the field conditions
(since the authors performed scale modeling of a submerged collector, it allowed us
to use the data from the laboratory experiments to get the estimates for the field
conditions employing similarity coefficients). The wind speed taken for the estimates was 5 m/s. The estimated phase velocities of IW were rather low as compared to the group velocity of the surface waves at this wind speed, while the
synchronism condition was not satisfied. According to the estimates, the hydrodynamic contrasts reached 7% (Fig. 13), which could be detected by the application
of the special methods to the optical satellite images. Ermakov and Salashin [24]
reported that hydrodynamic contrasts can be increased 7–8 times for the bound
waves (harmonics of the free waves); thus, the estimates of the hydrodynamic
contrasts for such waves can increase up to ∼60%.
Taking into account the presence of the free waves, the probability of finding a
bound wave is 50% at the wind speed 5 m/s, thus, the final estimate of hydrodynamic contrasts for bound waves is 25%. These contrasts can be detected by remote
sensing.
Conclusions
In this contribution, we summarized the main results of the work on internal waves
generated by vertical turbulent plumes in stratified fluids, including the mechanisms
of IW generation, the structure of IW, and their surface manifestations.
The majority of results were obtained on the basis of modeling of submerged
wastewater outfalls in the ocean, and thus, they are applicable for the monitoring of
the coastal zone. The other potential implications include buoyant plumes generated
by subglacial discharge in the Greenland fjords [22]. Fresh water from the surface
of the marine-terminated glaciers can percolate through the channels inside the
glacier and come out at the base of the glacier forming a buoyant plume. Those
turbulent plumes propagating along the ice face can significantly increase the rates
of glacier melting, and account for their presence could improve the predictions of
the melt rates. However, the locations of the plumes are difficult to identify. The IW
in this case could serve as an indication of the submerged plume. The proper
analysis, however, should include the sediment load in such a flow, and more
important, the presence of an ice wall.
The challenges related to this topic can be formulated as follows:
More complicated stratifications have to be considered in order to understand the
effect of stratification on the internal waves generated by the vertical oscillations of
82
V. G. Bondur et al.
at the surface. Hydrodynamic contrast was defined as M(k) = N1/N0, where N0 is
the spectral action density of an undisturbed surface wave spectrum, and N1 corresponds to the perturbations in the spectral action density due to the horizontal
surface currents induced by IW. Bondur et al. [11] solved the spectral action
balance equation [30], using the estimates of IW parameters for the field conditions
(since the authors performed scale modeling of a submerged collector, it allowed us
to use the data from the laboratory experiments to get the estimates for the field
conditions employing similarity coefficients). The wind speed taken for the estimates was 5 m/s. The estimated phase velocities of IW were rather low as compared to the group velocity of the surface waves at this wind speed, while the
synchronism condition was not satisfied. According to the estimates, the hydrodynamic contrasts reached 7% (Fig. 13), which could be detected by the application
of the special methods to the optical satellite images. Ermakov and Salashin [24]
reported that hydrodynamic contrasts can be increased 7–8 times for the bound
waves (harmonics of the free waves); thus, the estimates of the hydrodynamic
contrasts for such waves can increase up to ∼60%.
Taking into account the presence of the free waves, the probability of finding a
bound wave is 50% at the wind speed 5 m/s, thus, the final estimate of hydrodynamic contrasts for bound waves is 25%. These contrasts can be detected by remote
sensing.
Conclusions
In this contribution, we summarized the main results of the work on internal waves
generated by vertical turbulent plumes in stratified fluids, including the mechanisms
of IW generation, the structure of IW, and their surface manifestations.
The majority of results were obtained on the basis of modeling of submerged
wastewater outfalls in the ocean, and thus, they are applicable for the monitoring of
the coastal zone. The other potential implications include buoyant plumes generated
by subglacial discharge in the Greenland fjords [22]. Fresh water from the surface
of the marine-terminated glaciers can percolate through the channels inside the
glacier and come out at the base of the glacier forming a buoyant plume. Those
turbulent plumes propagating along the ice face can significantly increase the rates
of glacier melting, and account for their presence could improve the predictions of
the melt rates. However, the locations of the plumes are difficult to identify. The IW
in this case could serve as an indication of the submerged plume. The proper
analysis, however, should include the sediment load in such a flow, and more
important, the presence of an ice wall.
The challenges related to this topic can be formulated as follows:
More complicated stratifications have to be considered in order to understand the
effect of stratification on the internal waves generated by the vertical oscillations of
82
V. G. Bondur et al.