HOOV1 (Hoover, CA, Lat. 38.0887, Long. -119.1759, Alt. 2566) Print-Friendly Version Print-Friendly Version (B&W)
1 year and 5 month aerosol data are available in Hoover during the sampling period of 1997 - 2002. As shown in Figure 1, the overall average total light extinction coefficient (Bext) is 25.4 Mm-1 (Visual Range ~ 154 Km; Deciview ~ 9.3). The average PM2.5 mass concentration is 3.7 mg/m3. The average contributions of the major aerosol components to Hoover haze are particulate sulfate 12.8%, nitrate 5.2%, organic matter (OMC) 23.4%, elemental carbon (light absorbing carbon, LAC) 6.5%, fine soil 3.4% and coarse mass (CM) 9.4%.
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 40.6 Mm-1, which is about 12.5 times of the value of 3.3 Mm-1 during the 20% best days and 3.8 times of the value of 10.6 Mm-1 during the middle 60% days. OMC is the largest contributor to aerosol light extinction during the 20% worst days, and the contribution of OMC to aerosol light extinction is ~ 48.4% in worst days.
Figure 3 suggests that the highest occurrence of the 20% worst days happened in August, in which ~67% of the sampling days are the 20% haziest days at Hoover. As shown in Figure 4, OMC is the largest aerosol contributor to haze in August, with a contribution of ~54% in the 20% worst days. Relatively high light extinction coefficients are found in February, and dominated by dust components (fine soil + CM).
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)
