RAFA1 (San Rafael, CA, Lat. 34.7339, Long. -120.0073, Alt. 953) Print-Friendly Version Print-Friendly Version (B&W)
2 year and 10 month aerosol data are available in San Rafael during the sampling period of 1997 - 2002. As shown in Figure 1, the overall average total light extinction coefficient (Bext) is 44.4 Mm-1 (Visual Range ~ 88 Km; Deciview ~ 14.9). The average PM2.5 mass concentration is 5.6 mg/m3. The average contributions of the major aerosol components to San Rafael haze are particulate sulfate 28.9%, nitrate 18.8%, organic matter (OMC) 13.2%, elemental carbon (light absorbing carbon, LAC) 4.5%, fine soil 1.7% and coarse mass (CM) 10.3%.
Figure 1 Average contributions of major aerosol chemical components to light extinction (Based on data available in 1997-2002) (B&W)
Figure 2 Average contributions of major aerosol chemical components to light extinction in 20% best, middle 60% and 20% worst days (Based on data available in 1997-2002) (Data Table) (B&W)
As Figure 2 indicates, the average aerosol light extinction coefficient (Bext – Rayleigh Scattering (10 Mm-1)) during the 20% worst days is 59.0 Mm-1, which is about 5.9 times of the value of 10.0 Mm-1 during the 20% best days and 1.7 times of the value of 34.1 Mm-1 during the middle 60% days. Sulfate is the largest contributor to aerosol light extinction, with a contribution of 39% in the 20% worst days. Nitrate also contributes 25% to the aerosol light extinction in the 20% worst days.
Figure 3 suggests that the highest occurrence of the 20% worst days happened in August, in which ~ 50% of the sampling days are the 20% haziest days at San Rafael, and OMC and sulfate are two of the largest aerosol contributors to haze in the 20% worst days with a contributions of 29% and 27%, respectively. As shown in Figure 4, nitrate is the largest aerosol contributor to haze in the 20% worst days in January, February, March and November, with a contribution of ~ 35 - 55%. Sulfate is the largest aerosol contributor for the rest of the year except August, with a contribution of 30 - 45% in the 20% worst days.
Figure 3 Percentage of sampling days that are 20% worst days in each month (Based on data available in 1997-2002) (Data Table) (B&W)
Figure 4 Average contributions of major aerosol chemical components to light extinction during 20% worst days in each month (Based on data available in 1997-2002) (Data Table) (B&W)
