CCSM Atmospheric Model Working Group Summary J. J. Hack, D. A Randall AMWG Co-Chairs CCSM Workshop, 28 June 2001 CCSM Workshop, 28 June 2001

Strengths of New Model n Improvements in several important simulation features –precipitable water –precipitation distribution –polar surface radiation fluxes –eastern ocean solar energy budget –eastern Pacific surface wind stress n Scientifically defensible & extendible framework –spectral Eulerian dynamics with reduced linear grid –26 levels –prognostic cloud water –generalized cloud overlap (plus requisite changes to LW & SW) –updated long wave water vapor absorption formulation –modified deep convection parameterization

June 2001 Workshop Participation n 12 oral and 8 poster presentations on variety of topics –radiation transfer schemes –planetary boundary layer –cloud parameterization techniques –high resolution & extended domain simulations –numerical methods –diagnostic approaches and analyses n Open discussion –science and development priorities –issue-oriented focus groups n e.g., double ITCZ, clouds,...

AMWG Development Process n Extend Standard Experimental Procedures –uncoupled/coupled experimental frameworks –incorporation of tracers n Extend Standard Diagnostic Procedures –more comprehensive evaluation of proposed changes n include variability measures –model against observations; model against model –make all development activities & results web accessible n entrain broader community as participants in model analysis

Immediate Future for the AMWG n Maintain general AMWG research infrastructure –needs to support research activities on multiple fronts n boundary layer n dynamical cores n stratiform clouds n middle atmosphere (e.g., WACCM) n radiation parameterization alternatives n cumulus parameterization alternatives n AMWG diagnostic infrastructure –needs to continue to grow in scope and complexity n evaluate model behavior across wide range of time scales n include dominant modes of climate variability in standard analysis –continued involvement of other CCSM working groups

Other matters for exploration n Prioritize incorporation of new/improved physics –seek input from development, diagnostic, and application communities n Organize/prioritize activities around simulation deficiencies –solution for double ITCZ problem –solutions to weak internal variability –representation of clouds n Explore ways to establish stronger links to observational community –e.g., satellite remote sensing community