Lagrangian Model of the Sacramento Urban Plume
Abstract
To better understand the Sacramento urban plume evolution, measurements of hydrocarbons, nitrogen oxides, and ozone were obtained during summer 2001 near the University of California Blodgett Forest Research Station (UC BFRS) on the western slope of the Sierra Nevada Mountains and at Granite Bay, an eastern suburb of Sacramento. The measurements were used to constrain a Lagrangian plume model coupled to a full photochemical model. Model input included the temperature, pressure, boundary layer height, deposition rate of HNO3, concentration of H2O, appropriate rate constants, estimates of the background concentrations of VOC, NOy, O3, CO, and the concentrations of these chemicals at Granite Bay at time=0 and at UC BFRS at time=5 hours. Fitting to the data using a nonlinear least squares routine where the only adjustable parameters are the dilution rate and the H2CO concentration, we find that the dilution rate was 0.37 hr-1, and the formaldehyde concentration was 11 ppb. We varied the branching ratio to alkyl nitrate production and found an optimum at a value of 0.03. The model predicts an average OH concentration of 3.0 × 106 molecules/cm3.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2005
- Bibcode:
- 2005AGUFM.A51C0074B
- Keywords:
-
- 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0345 Pollution: urban and regional (0305;
- 0478;
- 4251);
- 0368 Troposphere: constituent transport and chemistry