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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