BAY AREA MODELING Status of Modeling Work Technical Committee Meeting November 18, 2003 Bay Area Air Quality Management District and Environ Corp.

Status of Bay Area/Environ Work Performing QA/QC for CCOS data Investigating potential causes of current underestimation of predicted ozone ( CAMx with CB-IV) –Meteorological fields (MM5 simulations) –Emissions (temperature inputs, wildfires, diesel NOx, weekday/weekend differences)

QA/QC of CCOS Data Temperatures: surface and RASS Winds: surface and profilers Ozone, NO, NOy: surface and aircraft NMOC: surface and aircraft

QA/QC of CCOS Data (cont.) Purpose: –Model input development –Model evaluation –Develop a conceptual model of ozone formation Problems found: –Units conversion errors –Missing aircraft coordinate data –Missing NMOC data

Meteorological Inputs CAMx model performance is sensitive to temperature –MM5 is under-predicting temperatures CAMx model performance is sensitive to sea-breeze strength –RAMS is over-predicting on-shore flow

Meteorological Inputs (cont.) Some MM5 parameters are not representative of the CCOS domain: –Soil moisture –Deep soil temperature –Surface roughness (land and sea) –Terrain barriers and terrain smoothing –Grid resolution

Livermore

Cool

Clovis

Arvin

Lodi

CAMx Simulations CAMx simulations show under- predictions of ozone Problem identified with CAMx albedo/haze/ozone column file –Ozone column too low –Higher ozone predicted with incorrect O3 column input

Emissions Revised temperatures for biogenic and mobile source emissions –Significant differences between 3/03 and 4/03 emissions: temperature differences? –Analysis temperature fields under-predicted Bay Area and Sierra temperatures – Produced new hybrid temperature fields: RAMS/obs. –Relatively small differences in emissions and predicted ozone in the Bay Area

Emissions (cont.) Emissions Inventory Working Group to identify potential uncertainties –Diesel NOx, especially in SJV –Observed ratios of VOC/CO, NOx/CO not in agreement with MVEI estimates –Documentation will help direct efforts

Modeling Boundary Conditions Based on CCOS Aircraft Sampling * Recommended based on off-shore aircraft data ** Original CCOS boundary conditions.