Journal Article

Analyses of BlueSky Gateway PM2.5 predictions during the 2007 southern and 2008 northern California fires

Craig, Kenneth J., Larkin, Narasimham, Strand, Tara M., Raffuse, Sean, Wheeler, Neil, Sullivan, Dana, Pryden, Daniel, Rorig, Miriam, Solomon, Robert

2012

Overview

We evaluated predictions of hourly PM2.5surface concentrations produced by the experimental BlueSky Gateway air quality modeling system during two wildfire episodes in southern California (Case 1) and northern California (Case 2). In southern California, the prediction performance was dominated by the prevailing synoptic weather patterns, which differentiated the smoke plumes into two types: narrow and highly concentrated during an offshore flow, and diluted and well‐mixed during a light onshore flow. For the northern California fires, the prediction performance was dominated by terrain and the limitations of predicting concentrations in a narrow valley, rather than by the synoptic pattern, which did not differ much throughout the wildfire episode. There was an over‐prediction bias for the maximum values during this episode. When the predicted values were compared to observed values, the best performance results were for the onshore flow during the southern California fires, indicating that the coarse grid used by BlueSky Gateway appropriately represented these well‐mixed conditions. Overall, the southern California fire predictions were biased low and the model did not reproduce the high hourly concentrations (>240μg/m3) observed by the monitors. The predicted results performed well against the observations for the northern California fires, with a large number of predicted values within acceptable range of the observed values. Key Points BlueSky Gateway predicted daily PM2.5 concentrations during two large wildfires A range of prediction performance was found depending on meteorology and terrain Modeled wildfire emissions and model grid size contributed to prediction error

• Publisher: Blackwell Publishing Ltd,American Geophysical Union
• Subject: BlueSky Framework / BlueSky Gateway / Earth sciences / Earth, ocean, space / Exact sciences and technology / prediction evaluation / smoke concentrations / wildfire PM2.5