MONT1 (Monture, MT, Lat. 47.1222, Long. -113.1543, Alt. 1293) Print-Friendly Version Print-Friendly Version (B&W)
2 year and 10 month aerosol data are available in Monture during the sampling period of 1997 - 2002. As shown in Figure 1, the overall average total light extinction coefficient (Bext) is 33.7 Mm-1 (Visual Range ~ 116 Km; Deciview ~ 12.1). The average PM2.5 mass concentration is 4.4 mg/m3. The average contributions of the major aerosol components to Monture haze are particulate sulfate 13.3%, nitrate 3.8%, organic matter (OMC) 37.5%, elemental carbon (light absorbing carbon, LAC) 7.2%, fine soil 2.0% and coarse mass (CM) 6.5%.
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 66.9 Mm-1, which is about 10.7 times of the value of 6.2 Mm-1 during the 20% best days and 4.6 times of the value of 14.6 Mm-1 during the middle 60% days. OMC is the largest contributor to aerosol light extinction, with a contribution of 66% in the 20% worst days.
Figure 3 suggests that the highest occurrence of the 20% worst days happened in August, in which ~ 54% of the sampling days are the 20% haziest days at Monture. As shown in Figure 4, OMC is the largest aerosol contributor to haze in the 20% worst days from May to December, with a contribution of ~ 30% to as high as 72% in August. Sulfate is the largest aerosol contributor in January, March and April, with a contribution of ~ 30 - 45% 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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