Sea ice physical properties and their application to ocean-atmosphere interaction

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The long-standing concept that ocean-atmosphere interaction cannot occur through sea ice is invalid. We now understand sea ice provides a variably effective conduit for ocean-atmosphere exchange, particularly for CO2. It is now thought that sea ice (depending on its temperature) may produce CO2 as it forms or grows, which may be trapped within the ice and eventually exported to the deep ocean. These interactions are modulated by the shape, location and connectivity of its liquid and gas inclusions, the intrinsic properties of which are controlled by a vertical temperature gradient within the ice and depend also on the sea ice type and age. We aim to characterize the size, shape, location and connectedness of liquid and gas inclusions in sea ice and changes therein from formation to melting. These results are imperative in determining how much atmospheric CO2 may be sequestered in polar oceans over an annual cycle both through, and as a result of, sea ice processes.***A significant obstacle to this work is the traditional methodology for sea ice sampling. That is, the vertical removal of a sea ice core from a larger volume and its subsequent storage at -20°C. Once a sea ice core sample is pulled upward and out of sea ice floating in the ocean, it's no longer connecting the ocean and atmosphere, and the vertical temperature gradient that controls much of the physics we're interested in is irreparably affected. This is especially relevant to the bottom portion of the sea ice bathed in ocean water through liquid channels extending upward into it. A useful analogy is a sponge removed from a sink of water. Removing the sponge from the sink and slicing it up it to see how much water it contained may not yield realistic results. ***The overarching goal of this program is methodological development. The limitations of sea ice coring and sample storage have been known for a long time; my students and I will endeavour to employ existing imaging techniques long used in other areas, and develop new state-of-the-art methods for the non-invasive measurement of the shape, location and type of sea ice inclusions. We would like to quantify how much liquid and air are in the proverbial sponge when it is floating in the sink, while it is floating in the sink.***This work will greatly expand current knowledge on how sea ice affects the biogeochemical processes and CO2 fluxes between the ocean and atmosphere in polar seas. Results of this work will include a long-sought observationally-derived library of permeability data for sea ice, partitioned relatively by phase, (including liquid brine, gases and solid salts) for a variety of sea ice stages of development as a function of naturally wide ranging physical conditions. These results are vitally important for verification of existing theoretical approximations and modeling of sea ice brine retention, brine drainage and greenhouse gas transport through sea ice to the ocean below. *****