Arctic Systems Modeling Workshop, Montreal July 2009 Atmospheric Breakout: Led by John Walsh, Notes by Scott Elliott First list atmospheric issues mentioned in morning session: Response of atmosphere to ocean and terrestrial change Cloud modeling with chemistry Rapid (abrupt) climate change The breakout group adds among others: Connections to ice, river inflow via precip, carbon cycle Connections to land model components -vegetation Biomass burning, wildfires Albedo alterations for land, ocean, clouds, ice Winds and the Greenland ice sheet

Seasonality -winter inversion and particles, summer fires Wet deposition does not work well in Arctic Shifts in flow and fate/transport of pollutants Asia plays in but also, increased ship traffic as ice recedes Biogeochemistry currently playing catch-up in regional codes Data lacking but field campaigns and satellite instruments coming All aspects need to be coherent from regional to global scale But two way nesting to the big models very difficult Domains and boundaries should be flexible for sensitivity tests How to use results -compare quantities themselves or interrelations Latter critical for systems modeling

How to improve measurements -distribute inexpensive experiments Aircraft, sondes, other Centralize model output and validation? Consensus this is critical and CMIP, PCMDI both cited Make data accessible in an enforced format such as netcdf Social aspects -visits and interactions including international Don’t forget weather forecasting and basic meteorology Systems models must wrap in impacts, human dimension, feedbacks Pursue specific projects, such as HydroQuebec