THE USE OF NWP TYPE SIMULATIONSTO TEST CONVECTIVE PARAMETERIZATIONS

David WilliamsonNational Center for Atmospheric Research

CCPP-ARM Parameterization Testbed (CAPT)

Steve Klein, Jim Boyle, Ric Cederwall, Mike Fiorino,Jay Hnilo, Tom Phillips, Jerry Potter, Shaocheng Xie

PCMDI / LLNLDavid Williamson, Jerry Olson

NCAR

WCRP / CAS WGNE TRANSPOSE AMIP

Martin Miller, Christian JakobECMWF

David WilliamsonNCAR

Parameterization Modifications

Guang ZhangScripps Institute of Oceanography

Richard NealeNCAR

Forecasts with climate modelsfrom operational analyses and reanalysesat climate model resolution

Gain insight into parameterization errorsby comparing parameterized variables to estimates from

field campaigns (e.g. ARM)when states fed to parameterizations are still close to

atmospheric analyses

Also useful just to examine model state errors

Map fine resolution NWP analyses to coarse resolutionclimate model grid

Spin-up land and parameterized variables to be consistentwith atmosphere forced to follow observed atmosphere(or apply a Global Land Data Assimilation System)

Additional benefit: establish sensitivity of parameterizationbehavior to different analyses

NWP goal – make best possible forecast of evolving weatherSpin-up of precipitation is common problem

occurs because model is inconsistent with analysesPrecipitation ignored for first few hours of forecast

Our goal – gain insight into model errorsSpin-up is primary signal

SPIN-UP DURING FORECAST

Forecasts withCommunity Atmosphere Model (CAM3 and CAM2)

coupled toCommunity Land Model (CLM3 and CLM2)

Initialized from ERA40

TOGA-COARE IFA (November 1997)CSU Verification data

Data sets for forcing and diagnosing SCM(Ciesielski et al. , 2003)

ARM SGP (June/July 1997 IOP)ARM Verification data

Data sets for forcing and diagnosing SCM and CRMvariational analysis (Zhang and Lin, 1997)

TOGA COARE Intensive Flux Array (IFA)

1-30 November 1992

CSU data fromhttp://tornado.atmos.colostate.edu/togadata/ifa_data.html

TOGA COARE IFA Nov ‘92

Solid – CAM3, Dashed – CSU

ARM SGP July ‘97

CAM2

CAM3

20 June – 13 July 1997

IFA Nov ‘92 SGP July ‘97

FORECAST ERRORS

Temperature Balance Equation

June-July ’97 SGP

June-July ’97 SGP

CONDENSATE FORMATION RAINFALL EVAPORATION

FREEZING OF RAIN MELTING OF SNOW

June-July ’97 SGP

June-July ’97 SGP

CONDENSATE FORMATION RAINFALL EVAPORATION

FREEZING OF RAIN MELTING OF SNOW

June-July ’97 SGP

CONDENSATE FORMATION RAINFALL EVAPORATION

June-July ’97 SGP

CONDENSATE FORMATION RAINFALL EVAPORATION

June-July ’97 SGP

June-July ’97 SGP

CAM3 CAM3 WITH ZHANG MOD CAM3 WITH NEALE MOD

CONCLUSIONS

•When Zhang is active, troposphere too warm•Errors larger in CAM3 than CAM2 (at SGP)

Convective time scale halved in CAM3Conversion between water and ice added to CAM3Rainfall evaporation dependence on cloud fraction in CAM3

CONCLUSIONS

•Composite over like process errors•Field campaign measurements essential

Need a large variety of cases•Do not tell what is wrong with model•Indicate which processes are producing wrong state

Does not imply incorrect formulation•Indicates where to look first

to determine why processes act incorrectly•Speculation (hypotheses)

for further experiments and examination

POSTERS

Willett, M., P. Bechtold, D. Williamson, J. Petch and S. Milton, 2006:Modelling the transition from suppressed to deep tropical convection:Comparison of global NWP and climate models with TOGA-COARE (GCSS WG4 Case5).

Xie, S., S. Klein, J. Boyle, D. Williamson, and G. Zhang, 2006:Identifying Climate Model Deficiencies in Simulations of Tropical Intraseasonal Variability by Running Climate Model in Forecast Mode and Using Single-Column Model.

Phillips, T. J., G. L. Potter, D. L. Williamson, R. T. Cederwall, J. S. Boyle, M. Fiorino, J. J. Hnilo, J. G. Olson, S. Xie, J. J. Yio, 2004: The CCPP-ARM Parameterization Testbed (CAPT): Where Climate Simulation Meets Weather Prediction, Bull. Amer. Meteor. Soc., 85, 1903-1915. Boyle, J., D. Williamson, R. Cederwall, M. Fiorino, J. Hnilo, J. Olson,T. Phillips, G. Potter and S. Xie, 2005: Diagnosis of CommunityAtmospheric Model 2 (CAM2) in numerical weather forecast configurationat Atmospheric Radiation Measurement (ARM) sites,J. Geophys. Res., 110 doi:10.1029/2004JD005042.

Williamson, D. L., J. Boyle, R. Cederwall, M. Fiorino, J. Hnilo, J. Olson,T. Phillips, G. Potter and S. Xie, 2005: Moisture and Temperature budgetsat the ARM Southern Great Plains Site in forecasts with the CAM2,J. Geophys. Res. , 110 doi:10.1029/2004JD005109.

Williamson, D. L. and J. Olson, 2006: A comparison of forecast errors inCAM2 and CAM3 at the AMR Southern Great Plains Site, J. Climate, submitted.

SGPJune-July ’97 Forecast Errors

June-July Climate Errors

TOGA COARE IFA Nov ‘92