overview of cam status and simulations

AMWG MeetingApril 3-4, 2002


Overview of CAM status and simulations

Bill Collins and Jim HackNational Center for Atmospheric Research

Boulder, Colorado

• Update on model status, simulations, and release• Computational performance of CAM• Features of model simulations

http://www.ncar.ucar.edu/ncar/index.html



Topics

• Overview of status and analysis of CAM• Discussion of new diagnostic efforts• Discussion of new physics parameterizations• Update on extensions to model• Overviews of work on isentropic coordinates

by other modeling groups• Open discussion• Objectives for summer workshop




AgendaTue 1:00 PM Collins / Hack Overview of CAM simulation

1:45 PM Taylor et al Comparative assessment of climatology

NewNew 2:10 PM Boyle PNA and stationary wave patterns

2:20 PM Discussion

2:30 PM Bitz et al High latitude climate in CAM and CCSM

3:15 PM Maloney Convective variability for eastern Pacific

3:45 PM Sun et al Radiative & dynamical feedbacks in CAM

4:00 PM Rasch Modifications to prognostic H2O scheme

4:10 PM Zhang et al New formulation for stratiform cloudiness

Wed 9:00 AM Stephens et al Effects of new radiation parameterization

9:30 AM Khairoutdinov Tests of a super-parameterization

9:50 AM Sassi WACCM

10:10 AM

Boville Heating and kinetic energy dissipation

10:45 AM

Konor Generalized vert. coord. model at UCLA

11:30 AM

Randall Overview of isentropic coord. work at CSU

1:30 PM Discussion




Developments since June 2001 Workshop

Conducted first coupled simulations

Implementation/restructuring• implementation of new CAM design:

– parameterization interface– creation of constituents module

• addition of new ESMF time-manager• continued work on splitting dynamics and physics• incorporated “chunking” data structures (2D

decomposition)• other ongoing implementation changes

– shared constants, file naming conventions, etc.





Major modifications/improvements:

Fractional surface specification implemented and

validated works properly for all three dynamical cores introduces minor simulation changes

CSIM ice thermodynamics implemented and validated

• specified and prognostic snow cover implemented and evaluated

• slightly colder ice temperatures• reasonable seasonal cycle in snow cover





Numerous “minor” modifications/improvements:

Minghua Zhang prognostic cloud-water closure modification vertical diffusion on dry static energy update static energy instead of T between

parameterizations modifications required for coupled simulations

– changes to cloud drop number concentration over sea ice– changes to methodology for determining rain vs. snow

other changes required for middle-atmosphere configuration

• creation of final boundary datasets– SST and sea ice concentration




Upcoming Papers on CAM

• General overview• New sea-ice formulation• Finite volume dynamical core• Parameterization for statiform fractional cloudiness

• New H2O longwave and cloud overlap

• Hydrometeor evaporation mechanism• New global SST climatology• Fractional ice and land• Coupling of parameterizations with dynamical core• Heating and kinetic energy dissipation• Tracer transport




Release of CAM to Community

• CAM 2.0 and CCSM 2.0 will be released May 17 (’02)• Contents of release:

– Model component source code; build and run scripts– Three dynamical cores: EulerianEulerian, semi-Lagrange, and Finite

Volume– Web-based documentation

• User’s Guide (how to run the model)• Reference Guide (details of the code structure)• Scientific Guide (description of physics and dynamics)

– Initial and boundary data sets • New SST and sea-ice concentration data

– Model data sets:• AMIP-2 and climatological SST uncoupled integrations

(Eulerian dynamics)




Computational Performance

• Supported platforms:– Compaq– IBM-SP– Linux: Portland group and Lahey compilers– SGI– Sun

• Performance:– 1 month per 32 wall-clock minutes on 32 IBM Power3 Pes– Equivalent to ~4 years per wall-clock day on same setup– Reduced grip speed-up: 25-30% (Eul. & SLD uncoupled

only)




TOA Energy ComponentsFractional Land/Sea Ice vs “Integer”

Representation




Surface Energy ComponentsFractional Land/Sea Ice vs “Integer”

Representation




Surface Energy FluxesFractional Land/Sea Ice vs “Integer” Representation

Latent Heat Flux

Precipitation Rate




Surface TemperatureCSIM Thermodynamic Ice vs “Old” Ice

Thermodynamics




New Blended SST-Sea Ice Concentration Data

Completed in collaboration with CVWG• blending technique developed by Jim Hurrell

– blends HadISST 1949-1980 with Reynolds 1979-2001 • screening technique to ensure reasonable SST-sea ice

relationship• PCMDI procedures for ensuring correctness of time interpolation • extensive quality control procedures

Fifty-three year dataset (1949-2001) can easily be extended as new SST data are created by NCEP currently have completed 21 year control experiment (1979-

2000)




Southern Oscillation Index




Sea Ice, Snow Height, and Precipitation

RateFractional Land/Sea Ice, CSIM Thermodynamics, New

SST




General Simulation Properties/Framework

Scientifically defensible & extendible framework• spectral Eulerian dynamics (reduced-grid capable)• T42 truncation• 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




General Simulation Properties/Framework

Improvements in several important simulation Improvements in several important simulation

featuresfeatures• precipitable water• precipitation distribution• eastern ocean solar energy budget• elements of eastern Pacific surface wind stress

Degradations in simulation featuresDegradations in simulation features• colder troposphere, particularly the tropical tropopause• tendency for more zonal double-ITCZ structure• warm surface temperature bias?




Temperature (coupled framework)




Surface Temperature (coupled framework)




Precipitable Water (coupled framework)




Precipitation Rate (coupled framework)




Surface Stress (coupled framework)




Net Longwave Surface Fluxes (coupled)




Net Surface Energy Flux (coupled)




Surface Temperature (against obs)




Eastern Pacific Surface Stress




E. Pacific Surface Stress: Resolution Dependence?




Future Work

Begin ensemble of ~50 year long control simulations• conducted in coordination with Climate Variability Working Group

– will serve as the basis for documenting simulation characteristics

Accelerate exploration of alternative dynamical frameworks

• T31 paleo configuration (update for fractional surface formulation)• T85 configurations (Eulerian and semi-Lagrangian for now)• continued evaluation of simulations with finite-volume dynamical core

Begin systematic investigation of specific simulation biases• AMWG should identify short list of prioritized projects

– eastern ocean upwelling, double ITCZ, cold tropopause temps, ...– climate sensitivity, variability (e.g., MJO), ...

• form teams to develop comprehensive scientific plan of attack– experimental strategy– diagnostic strategy




Future Work

• AMWG research infrastructure– needs to be able to support research activities on

multiple fronts• boundary layer• dynamical cores• stratiform clouds• middle atmosphere (e.g., WACM)• radiation parameterization alternatives• cumulus parameterization alternatives

• AMWG diagnostic infrastructure– needs to continue to grow in scope and complexity

• evaluate model behavior across wide range of time scales• include dominant modes of climate variability in standard analysis

– continued involvement of other CCSM working groups


overview of cam status and simulations

Documents

overview of cam status

model status

dynamical coreheating

scriptsthree dynamical

sea icechanges

prognostic snow cover

prognostic h2o scheme

pmzhang et alnew formulation