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Statistics- Definitions and Issues; Deriving “Unbiased Symmetric” Metrics
Shaocai Yu*, Brian Eder*++, Robin Dennis*++, Shao-Hang Chu**, Stephen Schwartz** *Atmospheric Sciences Modeling Division, NERL ** Office of Air Quality Planning and Standards U.S. EPA, RTP, NC ***Brookhaven National Laboratory, Upton, NY 11973 ++ On assignment from Air Resources Laboratory, NOAA
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Introduction
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CMAQ Community Multiscale Air Quality Model
Community Model Multiscale consistent model structures for interaction of urban through Continental scales Multi-pollutant ozone, speciated particulate matter, visibility, acid deposition and air toxics
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Symmetry: overprediction and underprediction are treated proportionately
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BNMBF: symmetry , (Range) -∞ to +∞, + is overprediction – is underprediction
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ENMEF: 0 to +∞
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Unbiased: avoid undue influence of small numbers in denominator
BNMBF: result of sum of indiv. factor bias with obs (or model) conc. as a weighting function
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Test of Metrics
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Test of Metrics (Continued) :11 models from IPCC (2001) (nss-SO42-)
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Test of Metrics (Continued) :11 models for nss-SO42-
Model H: best; Model A: worst Models E, G, H: acceptable If criteria: ±25% (BNMBF), 35% (ENMEF)
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Application of new Metrics for CMAQ evaluation
Jan. 8 to Feb. 18, 2002
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Application of new Metrics (Continued)
Jan. 8 to Feb. 18, 2002
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Contacts: Brian K. Eder
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