09:00 to 09:35 Registration 09:35 to 09:45 Welcome from David Abrahams (INI Director) 09:45 to 10:30 Donald K. Perovich Small to big, quick to slow: The many scales of sea ice properties and processes Sea ice properties and processes exhibit tremendous variability over spatial scales from millimeters to megameters. Sea ice also evolves over temporal scales of hours to days to seasons to decades. To understand sea ice properties, it is critical to examine and connect the processes that occur on these different scales. For example, sea ice microstructure impacts the partitioning of sunlight. Melt ponds are governed by meter-scale topography and millimeter-scale brine channels. There are similarities in the size distributions of brine pockets, melt ponds, and floes; features that span spatial scales of several orders of magnitude. The timing of short term events, such as snowfall or lead openings, has a large impact on the seasonal evolution of the ice cover. Sea ice scale issues are also important when considering the interactions of the atmosphere-sea ice-ocean-biogeochemical system. INI 1 10:30 to 11:00 Morning Coffee 11:00 to 11:45 Ken Golden Linking scales in the sea ice system Sea ice exhibits complex structure ranging from the sub-millimeter scale brine inclusions to ice floes and coherent​ ​dynamics on the scale of hundreds of kilometers. I will give an overview of how we are using​ ​ theories of composite​ materials and statistical physics to link behavior on various scales in the sea ice system. In particular, we address key questions in sea ice homogenization, where information on smaller scales is incorporated into rigorous representations of effective large scale behavior. We also consider the inverse problem where small scale structure is inferred from larger scale effective properties. INI 1 11:45 to 12:30 Agnieszka Herman Discrete-element models of sea ice dynamics and fracture At geophysical scales, continuum models provide established and computationally efficient tools for simulating sea ice dynamics and thermodynamics. In recent years, rapidly increasing computational power and availability of high-resolution (esp. remote-sensing) data have contributed to a revival of discrete-element methods (DEM), enabling the analysis of sea ice at smaller spatial and temporal scales. Treating sea ice as a collection of individual, interacting floes, and thus recognizing it as an example of a granular material, opens a wide range of new tools and analysis possibilities for sea ice research. Bonded-particle DEM models enable to simulate brittle fragmentation of sea ice – a process that, in spite of substantial progress in recent years, still poses problems for continuum models. Moreover, there is growing evidence that the size distribution of sea ice floes has a substantial influence on a wide range of processes in the upper ocean, lower atmosphere and within sea ice itself, and it is in turn shaped by those processes. By directly taking into account fragmentation (i.e., floe formation) and dynamics of individual floes, DEMs provide tools to better understand complex interactions between sea ice, ocean and atmosphere acting at the floe-level.In this talk, I will present and discuss selected examples of the application of DEM models to sea ice dynamics and fragmentation problems. The examples will include: wind- and current-induced drift of fragmented (granular’’) sea ice, and the influence of ice concentration and floe-size distribution on the sea ice response to forcing; jamming phase transition under compressive and shear strain, and force transmission in ice subject to different strain fields; sea ice breaking by waves analyzed with a coupled DEM–hydrodynamic model. Unsolved problems and challenges (both computational and theoretical) related to the application of DEMs to sea ice will be presented as well.Most results presented in this talk were obtained with a Discrete-Element bonded-particle Sea Ice model DESIgn, implemented as a toolbox for the open-source numerical library LIGGGHTS (http://www.cfdem.com/). The code and documentation of DESIgn are freely available at http://herman.ocean.ug.edu.pl/LIGGGHTSseaice.html. INI 1 12:30 to 13:30 Lunch @ Wolfson Court 13:30 to 14:00 Break 14:00 to 14:30 Veronique Dansereau A new continuum rheological model for the deformation and drift of sea ice Co-authors: Pierre Saramito (CNRS-LJK), Jérôme Weiss (CNRS-ISTerre), Philippe Lattes (Total S.A. E&P)Axel Roy (1) Véronique Dansereau (2)* Jérôme Weiss (2)  Christian Haas (3) Matthieu Chevalier (4) 1 École Nationale de la Météorologie, Météo France, Toulouse, France 2 Institut des Sciences de la Terre, CNRS UMR 5275, Université de Grenoble, Grenoble, France 3 Alfred Wegener Institute, Bremerhaven, Germany 4 CNRM/GMGEC/IOGA Météo France, Toulouse, France Sea ice models are most often compared to each other and to observations in terms of the spatial distribution of the simulated ice thickness. An equally important, and perhaps more appropriate, metric to investigate the mechanical behaviour of the sea ice cover is the ice thickness distribution, i.e., the probability density function, of which some valuable information have been available for some time from drill-hole, upward looking submarine-mounted sonar (USL) and airborne electromagnetic (EM) sounding measurements. An important issue naturally arises when comparing sea ice thickness distributions based on measurements made at the meter scale with that estimated from regional and global sea ice model simulations, with a typical resolution of a few kilometres; the issue of scale dependance. Using USL sea ice draft profiles and EM thickness measurements, we investigate the scaling properties of the sea ice thickness over the Arctic to address the following question: how does the sea ice thickness distribution evolve with the scale of observation? The autocorrelation calculations performed here allow extending previous analyses based on single USL transects (up to 50 km-long) and point to long-range correlations in the thickness of the sea ice cover reaching as far as a few hundreds of kilometres. Multi-fractal analyses are conducted to investigate the variability of the the ice thickness distribution with the spatial scale of observation up to these scales. INI 1 14:30 to 15:00 Christopher Horvat Floe size and ice thickness distributions INI 1 15:00 to 15:30 Afternoon Tea 15:30 to 16:00 Courtenay Strong Filling the polar data gap with harmonic functions Coauthors: Elena Cherkaev and Kenneth M. Golden The “polar data gap” is a region around the North Pole where satellite orbits do not provide sufficient coverage for estimating sea ice concentrations. This gap is conventionally made circular and assumed to be ice-covered for the purpose of sea ice extent calculations, but recent conditions around the perimeter of the gap indicate that this assumption may already be invalid. We present partial differential equation-based models for estimating sea ice concentrations within the area of the data gap. In particular, the sea ice concentration field is assumed to satisfy Laplace’s equation with boundary conditions determined by observed sea ice concentrations on the perimeter of the gap region. This type of idealization in the concentration field has already proved to be quite useful in establishing an objective method for measuring the “width” of the marginal ice zone—a highly irregular, annular-shaped region of the ice pack that interacts with the ocean, and typically surrounds the inner core of most densely packed sea ice. Realistic spatial heterogeneity in the idealized concentration field is achieved by adding a spatially autocorrelated stochastic field with temporally varying standard deviation derived from the variability of observations around the gap. Testing in circular regions around the gap yields observation-model correlation exceeding 0.6 to 0.7, and sea ice concentration mean absolute deviations smaller than 0.01. This approach based on solving an elliptic partial differential equation with given boundary conditions has sufficient generality to also provide more sophisticated models which could be more accurate than the Laplace equation version, and such potential generalizations are explored. INI 1 16:00 to 17:00 Elizabeth Hunke Rothschild Lecture: Large-scale sea ice modeling: societal needs and community development The CICE sea ice model is used extensively by climate and Earth system research groups, and also by operational centers for applications such as numerical weather prediction and guidance for military operations.  While the research community is energetically improving the models, observationalists are busy taking measurements and operational experts are using all of it to produce predictive products via data assimilation.  In the past, the sea ice research and operational communities have been somewhat distinct with little cross-pollination.  Partly in response to this issue, the CICE Consortium has formed as a formal community effort to to provide a mechanism for accelerating further sea ice model development and its transfer into operational uses.  This colloquium will provide a broad overview of current CICE model capabilities and uses, highlight new analysis techniques for statistically assessing model skill against diverse observations, and discuss our community engagement effort, all toward addressing society's needs in the face of the Earth’s changing polar regions. INI 1 17:00 to 18:00 Rothschild Drinks Reception at INI