SAWT1 (Sawtooth National Forest, ID, Lat. 44.1706, Long. -114.9282, Alt. 1980) Print-Friendly Version Print-Friendly Version (B&W)
2 year and 2 month aerosol data are available in Sawtooth National Forest during the sampling period of 1997 - 2002. As shown in Figure 1, the overall average total light extinction coefficient (Bext) is 24.0 Mm-1 (Visual Range ~ 162 Km; Deciview ~ 8.8). The average PM2.5 mass concentration is 3.2 mg/m3. The average contributions of the major aerosol components to Sawtooth National Forest haze are particulate sulfate 12.0%, nitrate 2.4%, organic matter (OMC) 29.5%, elemental carbon (light absorbing carbon, LAC) 8.2%, fine soil 1.9% and coarse mass (CM) 4.4%.
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 29.0 Mm-1, which is about 5.3 times of the value of 5.5 Mm-1 during the 20% best days and 2.4 times of the value of 11.9 Mm-1 during the middle 60% days. OMC is the largest contributor to aerosol light extinction, with a contribution of 59% in the 20% worst days.
Figure 3 suggests that the highest occurrence of the 20% worst days happened in August, in which ~ 60% of the sampling days are the 20% haziest days at Sawtooth National Forest. As shown in Figure 4, OMC is the largest aerosol contributor to haze in August, with a contribution of ~ 51% in the 20% worst days. OMC is the largest aerosol contributor to haze throughout the year. Its contribution is about 30 - 50% 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)
