GLAC1 (Glacier National Park, MT, Lat. 48.5104, Long. -113.9966, Alt. 979)

6 years aerosol data are available in Glacier National Park during the sampling period of 1997 - 2002. As shown in Figure 1, the overall average total light extinction coefficient (Bext) is 39.4 Mm-1 (Visual Range ~  99 Km; Deciview ~ 13.7). The average PM2.5 mass concentration is 5.3 mg/m3. The average contributions of the major aerosol components to Glacier National Park haze are particulate sulfate 21.2%, nitrate 6.9%, organic matter (OMC) 26.3%, elemental carbon (light absorbing carbon, LAC) 8.9%, fine soil 1.8% and coarse mass (CM) 9.5%. 

Bext = 39.4 Mm-1

Figure 1 Average contributions of major aerosol chemical components to light extinction (Based on data available in 1997-2002)

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)

As Figure 2 indicates, the average aerosol light extinction coefficient (Bext – Rayleigh Scattering (10 Mm-1)) during the 20% worst days is 59.3 Mm-1, which is about 5.5 times of the value of 10.7 Mm-1 during the 20% best days and 2.3 times of the value of 25.5 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  ~ 38.3% in the 20% worst days. Sulfate also contributes 23.8% to aerosol light extinction in the worst days.

Figure 3 suggests that the highest occurrence of the 20% worst days happened in August and November, in which ~40% of the sampling days are the 20% haziest days at Glacier National Park. As shown in Figure 4, OMC is the largest aerosol contributor to haze in August and November, with a contribution of ~ 40% in the worst days. Sulfate also contributes ~20% in November. CM is also an important aerosol contributor to haze in the summer, with a contribution of 20-30% 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)

 

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)