Laboratory Experiments on Internal Solitary Waves in Ice-Covered Waters

Internal solitary waves (ISWs) propagating in a stably-stratified two-layer fluid in which the upper boundary condition changes from open water to ice are studied for cases of grease, level and nilas ice. The ISW-induced current at the surface is capable of trans-porting the ice in the horizontal direction. In the level ice case, the transport speed of, relatively long ice floes, non-dimensionalised by the wave speed is linearly dependent on the length of the ice floe non-dimensionalised by the wave length. Measures of turbulent kinetic energy dissipation under the ice are comparable to those at the wave density interface. Moreover, in cases where the ice floe protrudes into the pycnocline, interaction with the ice edge can cause the ISW to break or even be destroyed by the process. The results suggest that interaction between ISWs and sea ice may be an important mechanism for dissipation of ISW energy in the Arctic Ocean

Oil spill response capabilities and technologies for ice-covered Arctic marine waters: A review of recent developments and established practices

Renewed political and commercial interest in the resources of the Arctic, the reduction in the extent and thickness of sea ice, and the recent failings that led to the Deepwater Horizon oil spill, have prompted industry and its regulatory agencies, governments, local communities and NGOs to look at all aspects of Arctic oil spill countermeasures with fresh eyes. This paper provides an overview of present oil spill response capabilities and technologies for ice-covered waters, as well as under potential future conditions driven by a changing climate. Though not an exhaustive review, we provide the key research results for oil spill response from knowledge accumulated over many decades, including significant review papers that have been prepared as well as results from recent laboratory tests, field programmes and modelling work. The three main areas covered by the review are as follows: oil weathering and modelling; oil detection and monitoring; and oil spill response techniques

Air-ice carbon pathways inferred from a sea ice tank experiment

Air-ice CO2 fluxes were measured continuously using automated chambers from the initial freezing of a sea ice cover until its decay. Cooling seawater prior to sea ice formation acted as a sink for atmospheric CO2, but as soon as the first ice crystals started to form, sea ice turned to a source of CO2, which lasted throughout the whole ice growth phase. Once ice decay was initiated by warming the atmosphere, the sea ice shifted back again to a sink of CO2. Direct measurements of outward ice-atmosphere CO2 fluxes were consistent with the depletion of dissolved inorganic carbon in the upper half of sea ice. Combining measured air-ice CO2 fluxes with the partial pressure of CO2 in sea ice, we determined strongly different gas transfer coefficients of CO2 at the air-ice interface between the growth and the decay phases (from 2.5 to 0.4 mol m−2 d−1 atm−1). A 1D sea ice carbon cycle model including gas physics and carbon biogeochemistry was used in various configurations in order to interpret the observations. All model simulations correctly predicted the sign of the air-ice flux. By contrast, the amplitude of the flux was much more variable between the different simulations. In none of the simulations was the dissolved gas pathway strong enough to explain the large fluxes during ice growth. This pathway weakness is due to an intrinsic limitation of ice-air fluxes of dissolved CO2 by the slow transport of dissolved inorganic carbon in the ice. The best means we found to explain the high air-ice carbon fluxes during ice growth is an intense yet uncertain gas bubble efflux, requiring sufficient bubble nucleation and upwards rise. We therefore call for further investigation of gas bubble nucleation and transport in sea ice

OMAE2003-37397 TESTS ON DYNAMIC ICE-STRUCTURE INTERACION

ABSTRACT This paper addresses the problem of ice induced vibration of offshore structures. Compliant structures having vertical ice walls may suffer from very severe vibrations. Several theories have been proposed to predict these vibrations. However, physical details of this phenomenon are not fully understood. Conical structures are deemed to be less sensitive to vibrations. Recent full-scale measurements made in the Bohai Bay indicate that also these structures my experience excessive vibrations caused by ice. Indentation tests were done at the ARCTEC laboratory at the Hamburg Ship Model Basin, Hamburg to clarify details of ice induced vibration. Sheets of columnar grained saline ice was used in the tests. The parameters that were varied included the structure's compliance and damping, indentation velocity and the structural geometry at the water line. The paper provides tests results that were obtained using vertical and conical model structures

Overview of the results of the project ‘Loads on Structure and Waves in Ice’ (LS-WICE)

As an attempt to investigate several major research questions related to ocean wave-ice interaction, the HYDRALAB+ Transnational Access project ‘Loads on Structure and Waves in Ice’ (LS-WICE) was conducted in the Large Ice Model Basin (LIMB) at the Hamburg Ship Model Basin (HSVA) from 24 October to 11 November 2016. The experimental data from this extensive project have been analysed in several research studies reported in other scientific papers. Here, an overall review of the obtained results is presented, and some recommendations for further work are given based on the collected experience