amwg breakout, ccsm workshop june 25, 2002 overview of cam status and simulations bill collins and...

AMWG Breakout, CCSM WorkshopJune 25, 2002


Overview of CAM status and simulations

Bill Collins and Dave RandallNational Center for Atmospheric Research and

Colorado State University

• Breakout agenda & topics• Model status, simulations, & release• Features of model simulations

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



Topics

• Introduction:– Status of CAM release and model datasets– Discussion from April ’02 AMWG workshop– Overview of features in CAM simulations– Future directions for AMWG

• New methods for diagnosing CAM• Analysis of systematic errors in coupled and

uncoupled simulations• Ongoing development of new physics




11:00 AM 11:30 AM

Collins Overview of CAM Status & Simulations

11:30 AM 11:50 AM Williamson

CAM2 in the NWP Mode for Development

11:50 AM 1:15 PM LUNCH

1:15 PM 1:30 PM Bretherton E. Pacific CAM Simulation vs. Observations

1:30 PM 1:45 PM Kiehl Comparison of Cloud Response to SST Anomalies

1:45 PM 2:00 PM Boville Analysis of Tropopause Temperature Bias

2:00 PM 2:15 PM Briegleb CCSM2 Polar Atmosphere Simulation

2:15 PM 2:30 PM Donner Results on Donner Cumulus Parameterization

2:30 PM 2:45 PM Sassi Early WACCM Results with Interactive Chemistry

2:45 PM 3:00 PM Duffy Climate Simulations with High-Res. Global Model

3:00 PM 3:15 PM Wu Effects of CRM-Validated Parameterizations

3:15 PM 3:30 PM DISCUSSION

Agenda




New Features of CAM 2.0

Dynamics:• Addition of Finite Volume dynamical core• Process-split or time-split coupling between dynamics & physics

Physics:• Thermodynamic sea ice• Fractional ice and land• Updated prognostic cloud water• Generalized cloud overlap in radiation• More accurate formulation of H2O absorptivity/emissivity• Evaporation of precipitation

Boundary Conditions:• Blended SST and sea-ice data set for 1949-2001




• CAM 2.0 and CCSM 2.0 were released May 17, 2002http://www.ccsm.ucar.edu/models/atm-cam/

• 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)• TBD: Reference Guide (details of the code structure)• TBD: Scientific Guide (description of physics & dynamics)

– Initial and boundary data sets • New SST and sea-ice concentration data• TBD: Release of tools for interpolation to other resolutions

– Model data sets and data set diagnostics:• AMIP-2 & climatological SST uncoupled integrations (Eulerian)• CAM output from CCSM control integration (years 350-670)

Release of CAM2 to Community




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

• Additional CAM documentation coming shortly.

Updates to Release




Documentation of CAM2 Formulation and Principal Simulation Features

Peer-reviewed journal article is planned for early summer

• documentation of new parametric and numerical formulations

• documentation of principal simulation features

• documentation of simulation sensitivities– limited scope for the purposes of this manuscript

Abbreviated version of documentation effort completed for CCM3

“Developers” will be contacted electronically for participation shortly after the CCSM Workshop




• Main systematic errors discussed:– Double ITCZ (Simulating the Coupled Tropical Climate System)– Underestimation of tropical variability on short&MJO scales

(CVWG)– Overestimation of land surface temperatures in winter– Underestimation of tropical tropopause temperatures– Biases in the eastern Pacific: BL clouds, surface fields

• Steps necessary to analyze these problems:– Experimentation of alternative physics formulations

(coupled and uncoupled testing)– “Partial derivative experiments”– Column diagnostics from field experiments, buoys, etc.

April 2002 AMWG Meeting

• Main systematic errors discussed:– Double ITCZ – Underestimation of tropical variability on short&MJO

scales– Overestimation of land surface temperatures in winter– Underestimation of tropical tropopause temperatures– Biases in the eastern Pacific: BL clouds, surface fields

• Steps necessary to analyze these problems:– Experimentation of alternative physics formulations

(coupled and uncoupled testing)– “Partial derivative experiments”– Column diagnostics from field experiments, buoys,

etc.




April 2002 AMWG Meeting (cont).

• Recommendation to adopt FV for future development:– Diagnosis of model using results from the DAO

assimilation/forecast system built upon CAM2– Testing of isentropic coordinates– Superiority for applications involving chemistry & tracer

transport– Compatibility with WACCM development effort– Superior computational performance on massively parallel

systems relative to standard Eulerian dycore

• Recommendation to explore higher vertical and horizontal resolutions




Change in AMWG Leadership

• Current co-chair: Dave Randall

• New co-chair: Leo Donner




Precipitable Water

CCM3 CAM2-CCM3

CGD:

Improvements

CGD:

Improvements




Longwave Surface Fluxes

Clear:CAM2- CCM3 All-sky:CAM2-CCM3




Clear-Sky Longwave TOA Fluxes

CAM2- CCM3 CAM2




Relationship of SWCF and LWCF in Pacific




Land Surface Temperatures,CCSM2 & CAM2

CCSM2 CAM2

CGD:

Systematic errors

CGD:

Systematic errors




Land Surface Temperatures, Differences

CCSM2-CSM1 CAM2-CCM3




Tropopause Temperatures, CCSM2 & CAM2

CCSM2 CAM2




Tropopause Temperatures, Differences





Tropical Precipitation, CCSM2 & CAM2

CCSM2 CAM2




Tropical Precipitation, Differences





Eastern Pacific SSTs

CCSM2 CCSM2-CSM1




Eastern Pacific Surface State

CCSM2-CSM1 CCSM2




AMWG Directions, Near Term

• Climate applications of CCSM impeded by:– Double ITCZ and extended cold tongue– Underestimation of tropical variability on short&MJO scales– Overestimation of land surface temperatures in winter– Underestimation of tropical tropopause temperatures– Biases in the eastern Pacific: BL clouds, surface fields

• The AMWG must focus on analyzing and addressing these errors (where possible), in collaboration with other working groups, as the highest priority.

• Immediate task: develop experimental strategies:– Alternative physics formulations – “Partial derivative experiments”




AMWG Directions, Longer Term

Physics:

• Incorporation of major aerosol species

• New radiation parameterizations

• Alternative formulations of convective processes and transport

• New formulations for boundary layer structure and cloud systems

• Incorporation of simplified tropospheric chemistry

• Creation of unified parameterizations for boundary layer clouds, cloud/radiation interactions

Diagnostics:

• New frameworks for testing:

o Assimilation/forecasting (DAO)

o Initial error growth (CAGATE)

• Addition of EOS data, variability

Dynamics:

• Exploration of new dycores (FV)

• Exploration of isentropic coordinates


amwg breakout, ccsm workshop june 25, 2002 overview of cam status and simulations bill collins and...

Documents

status of cam release

pacific cam simulation

new sst

release of cam2

boundary data

seaice data set

release of tools

dynamics physics physics