Improving Cost Effective Air Improving Cost Effective Air Quality ForecastingQuality Forecasting
UPDATE 10/02/2008:UPDATE 10/02/2008:
•New Categorical Metrics (Kang 2007)New Categorical Metrics (Kang 2007)–Interpretation of new metricsInterpretation of new metrics–Use in AQ model evaluationUse in AQ model evaluation–Direct applications to cost-effective AQ Direct applications to cost-effective AQ forecastingforecasting
ReviewReview
• Project GoalsProject Goals– Minimize money spent due to incorrect forecastsMinimize money spent due to incorrect forecasts
• MD/VA Free ride programMD/VA Free ride program– VA cost per day VA cost per day $120,000 $120,000– MDOT cost per day MDOT cost per day $35,000 - $40,000 $35,000 - $40,000
• National Air Quality Forecasting System National Air Quality Forecasting System (NAQFS) Updates(NAQFS) Updates– Domain, Surface parameters, canopy uptakeDomain, Surface parameters, canopy uptake
• Methods of Model EvaluationMethods of Model Evaluation– Discrete (RMSE, N/MB, N/ME, r)Discrete (RMSE, N/MB, N/ME, r)– Categorical (A, B, FAR, CSI)Categorical (A, B, FAR, CSI)– New Categorical (WSI, aH, aFAR) New Categorical (WSI, aH, aFAR) Kang 2007) Kang 2007)
Traditional Categorical MetricsTraditional Categorical Metrics
• Categorical EvaluationCategorical Evaluation– Ozone threshold exceeded?Ozone threshold exceeded?– Was it forecasted to exceed?Was it forecasted to exceed?
Forecast Forecast
ThresholdThreshold
a a MISSMISS HIGH HIGH
b b HITHIT HIGH HIGH
c c HITHIT LOW LOW
d d MISSMISS LOW LOW
Traditional Categorical MetricsTraditional Categorical Metrics
New Categorical Metrics (Kang 2007)New Categorical Metrics (Kang 2007)
• WSI WSI Weighted Weighted Severity IndexSeverity Index– Like CSI, only it Like CSI, only it
includes (to a includes (to a degree) near hitsdegree) near hits
New Categorical Metrics (Kang 2007)New Categorical Metrics (Kang 2007)
• Modeled vs. Observed O3Modeled vs. Observed O3• Area Hits (aH) and aFAR (Area False Alarm Rate) Area Hits (aH) and aFAR (Area False Alarm Rate)
account for spatial near-hitsaccount for spatial near-hits
New Categorical Metrics (Kang 2007)New Categorical Metrics (Kang 2007)
• Use 3x3 or 5x5 grid spaces to account for areaUse 3x3 or 5x5 grid spaces to account for area• Adjust the Hit forecast (b/b+d) to include the area Adjust the Hit forecast (b/b+d) to include the area
and not just the point…Same for FAR.and not just the point…Same for FAR.
Application to cost-effective AQ Application to cost-effective AQ forecastingforecasting
• Area forecasts are typical in operational Area forecasts are typical in operational
forecastsforecasts
– Warn an area, not a pointWarn an area, not a point
– aH and aFAR account for these!aH and aFAR account for these!
• Assign a percent chance of missed Assign a percent chance of missed
forecast using WSI?forecast using WSI?
• Decide minimum forecast value that Decide minimum forecast value that
statistically produces the best likelihood of statistically produces the best likelihood of
an exceedance?an exceedance?