Regional Arctic System Model (RASM): A Tool to Advance Understanding and Prediction of Arctic Climate Change at Process Scales
Wieslaw Maslowski1, Andrew Roberts2, Robert Osinski3, Michael Brunke4, John J Cassano5, Jaclyn L Clement Kinney1, Anthony Craig6, Alice K DuVivier7, Brandon J Fisel8, William J Gutowski Jr9, Joe Hamman10, Mimi Abel11, Bart Nijssen12 and Xubin Zeng4, (1)Naval Postgraduate School, Monterey, CA, United States, (2)Lost Alamos National Laboratory, Los Alamos, United States, (3)Institute of Oceanology Polish Academy of Sciences, Sopot, Poland, (4)University of Arizona, Department of Hydrology and Atmospheric Sciences, Tucson, AZ, United States, (5)Univ Colorado, Boulder, United States, (6)Not affiliated, Seattle, United States, (7)NCAR, Boulder, United States, (8)Iowa State University, Ames, IA, United States, (9)Iowa State University, Geological & Atmospheric Sciences, Ames, IA, United States, (10)National Center for Atmospheric Research, Hydrometeorological Applications Program, Research Applications Laboratory, Boulder, CO, United States, (11)Univ Colorado, Boulder, CO, United States, (12)University of Washington, Department of Civil and Environmental Engineering, Seattle, WA, United States
Abstract:
The Arctic is undergoing rapid climatic changes, which are some of the most coordinated changes currently occurring anywhere on Earth. They are exemplified by the retreat of the perennial sea ice cover, which integrates forcing by, exchanges with and feedbacks between atmosphere, ocean and land. While historical reconstructions from Global Climate and Global Earth System Models (GC/ESMs) are in broad agreement with these changes, the rate of change in the GC/ESMs remains outpaced by observations. Reasons for that stem from a combination of coarse model resolution, inadequate parameterizations, unrepresented processes and a limited knowledge of physical and other real world interactions.
We demonstrate the capability of the Regional Arctic System Model (RASM) in addressing some of the GC/ESM limitations in simulating observed seasonal to decadal variability and trends in the sea ice cover and climate. RASM is a high resolution, fully coupled, pan-Arctic climate model that uses the Community Earth System Model (CESM) framework. It uses the Los Alamos Sea Ice Model (CICE) and Parallel Ocean Program (POP) configured at an eddy-permitting resolution of 1/12° as well as the Weather Research and Forecasting (WRF) and Variable Infiltration Capacity (VIC) models at 50 km resolution. All RASM components are coupled via the CESM flux coupler (CPL7) at 20-minute intervals.
RASM is an example of limited-area, process-resolving, fully coupled earth system model, which due to the additional constraints from lateral boundary conditions and nudging within a regional model domain facilitates detailed comparisons with observational statistics that are not possible with GC/ESMs. In this talk, we will emphasize the utility of RASM to understand sensitivity to variable parameter space, importance of critical processes, coupled feedbacks and ultimately to reduce uncertainty in arctic climate change projections.
