1. 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

2. Introduction

4. 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

6. Symmetry: overprediction and underprediction are treated proportionately

7. BNMBF: symmetry ,
(Range) -∞ to +∞,
+ is overprediction
– is underprediction

8. ENMEF: 0 to +∞

9. 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

10. Test of Metrics

11. Test of Metrics (Continued) :11 models from IPCC (2001) (nss-SO42-)

12. 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)

13. Application of new Metrics for CMAQ evaluation
Jan. 8 to Feb. 18, 2002

14. Application of new Metrics (Continued)
Jan. 8 to Feb. 18, 2002

15. Contacts:
Brian K. Eder