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Mesoscale model ensemble for MDSS. Paul Schultz NOAA Forecast Systems Laboratory March 2001. Purpose of ensemble modeling . Ensemble of model forecasts has been shown to be a better forecast than any single ensemble member (1+1=3!)
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Mesoscale model ensemble for MDSS Paul Schultz NOAA Forecast Systems Laboratory March 2001
Purpose of ensemble modeling • Ensemble of model forecasts has been shown to be a better forecast than any single ensemble member (1+1=3!) • Demonstrated on global scale (NCEP), “large” regional scale (SAMEX), not yet at “local” scale, but no reason to believe it won’t work • Ensemble members can be used to create probabilities for key predictands • e.g., t < 32ºF, V>25kt, etc.
The dilemma -- the research opportunity • Are computer resources best spent on ensemble modeling, or a single (or few) at maximum resolution? • MDSS project can shed some light. • FSL’s jet computer lets us do both.
Configuration • Four 48-hr forecasts per day • 12-km grid • Two high-resolution MM5 nests • 4-km grid • centered on SLC, DEN • Four 12-hr forecasts per day • Benchmarking spreadsheet Status:
This is the domain for the nine ensemble members;the fine-mesh nests are outlined in red
Ensemble products • State variables: t, , rh, etc. • Categorical probability of precipitation (PoP), probability of precipitation type (PoPT) • Probabilities of key forecast variables