Air Quality Ensemble Forecast Over the Lower Fraser Valley, British Columbia

The ensemble-averaging approach is potentially a technique for improving the performance of real-time photochemical air-quality modeling. Ensemble photochemical air-quality forecasts are tested extensively using the Community Multiscale Air Quality (CMAQ) model-system with mesonet observations from the Emergency Weather Net (EmWxNet) and the AQ Data Set over the Lower Fraser Valley (LFV). The CMAQ model is run daily over a 12 km resolution domain (Figure 1 top) covering southern British Columbia, Washington State, and the northern portion of Oregon State. A 4 km resolution grid (Figure 1 bottom) is nested within the 12km grid, and it covers the southern tip of British Columbia (including Vancouver and the LFV) and the northern part of Washington State (including the Seattle area). CMAQ is driven by two different meteorological models: the Mesoscale Compressible Community Model (MC2), and the Fifth-Generation NCAR/Penn State Mesoscale Model (MM5).