Arctic Systems Modeling Workshop, Montreal July 2009 (notes by Elliott) Afternoon Breakout Summaries: Day 1 Holland leads Ice Sheets Sea level change the driver -complex in itself Sheet models vary in detail up to fast ice streams Coastal interactions usually missing Simulated ocean must change volume to invade fjords Resolution must deal with coastal topography Even finer at grounding line, perhaps dynamic/adaptable Uncouple components as pedagogical device to start Better physics parameterizations required -e.g. calving As always observations are limited/limiting

Walsh leads Atmosphere Existing efforts listed as examples -WRF, others Domain must be flexible, amenable to sensitivity tests Data centralization one of the keys -CMIP, PCMDI Coherent global to regional interactions -Canadian system Integrate emerging modules -e.g. chemistry entering WRF Externals include biogeochemistry, surfaces, albedo Impacts, vulnerability link to customers -Human aspects Aim for extensibility, proceed in steps -chemistry, aerosol, etc. Feedbacks demand a range of time scales up to decades

Flato leads Sea Ice-Ocean Science questions abound -too numerous to list They focus on several challenges to the prevailing wisdom Is an Arctic Systems Model the proper venue? Perhaps a suite of tools and development is the real story Prioritization will be critical Regional models can only downsize, must talk to global Nudging discussed as a means to keep regional codes on track Decentralization of data may be preferable Cherry leads Terrestrial/Permafrost Permafrost to biogeochemistry links -methane and C in general Lakes need to encompass subgrid scale, thermokarst Vegetation should be dynamic Vertical resolution improving fast in soil models Gridded data sets, time series lacking on terrestrial side Huge gaps in understanding the human dimension Should ASM be CCSM like, with a single module set?

Steiner leads Biogeochemistry Great land problems, but participants mainly ocean community Began with impacts of trace gases on climate -e.g. DMS, N2O So obviously, system atmosphere must contain chemistry All driven by nutrient and organic cycling in upper column Higher trophic levels play in -up to fish, birds and mammals Ecosystem structure will morph in the future Links to albedo abound -DMS and CCN, chlorophyll in ice New developments -unexpected phases such as ikaite in ice Clathrate release of CH4 will be modulated by methanotrophs Regional approach allows fine resolution, boundaries tough Centralization a strong yes but further, Involve modelers in design and implementation of experiments Emerging module examples -ice algae, sediments, clathrates