YOSE1 (Yosemite National Park, CA, Lat. 37.7125, Long. -119.7041, Alt. 1615) Print-Friendly Version Print-Friendly Version (B&W)
6 years aerosol data are available in Yosemite National Park during the sampling period of 1997 - 2002. As shown in Figure 1, the overall average total light extinction coefficient (Bext) is 32.4 Mm-1 (Visual Range ~ 121 Km; Deciview ~ 11.7). The average PM2.5 mass concentration is 4.7 mg/m3. The average contributions of the major aerosol components to Yosemite National Park haze are particulate sulfate 17.0%, nitrate 9.7%, organic matter (OMC) 26.8%, elemental carbon (light absorbing carbon, LAC) 6.9%, fine soil 1.7% and coarse mass (CM) 7.1%.
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 48.2 Mm-1, which is about 9.3 times of the value of 5.2 Mm-1 during the 20% best days and 2.4 times of the value of 19.7 Mm-1 during the middle 60% days. OMC is the largest contributor to aerosol light extinction, with a contribution of 45% in the 20% worst days.
Figure 3 suggests that the highest occurrence of the 20% worst days happened in August and October, in which ~ 50% of the sampling days are the 20% haziest days at Yosemite National Park. As shown in Figure 4, OMC and sulfate each contributes about 25 - 30% to haze in the 20% worst days from May to July. OMC dominates the light extinction from August to November, with a contribution of ~ 50%. One very high nitrate day is found in January of 1998, which may be caused by a specific pollution event. In the winter and early spring, the occurrence of 20% worst days is low, and Nitrate is the largest aerosol contributor in the 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)
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