ULBE1 (U. L. Bend Wilderness Area, MT, Lat. 47.5823, Long. -108.7196, Alt. 893) Print-Friendly Version Print-Friendly Version (B&W)
2 year and 11 month aerosol data are available in U. L. Bend Wilderness Area during the sampling period of 1997 - 2002. As shown in Figure 1, the overall average total light extinction coefficient (Bext) is 28.0 Mm-1 (Visual Range ~ 139 Km; Deciview ~ 10.3). The average PM2.5 mass concentration is 3.5 mg/m3. The average contributions of the major aerosol components to U. L. Bend Wilderness Area haze are particulate sulfate 23.7%, nitrate 10.5%, organic matter (OMC) 16.3%, elemental carbon (light absorbing carbon, LAC) 4.5%, fine soil 1.6% and coarse mass (CM) 7.8%.
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 37.4 Mm-1, which is about 5.8 times of the value of 6.5 Mm-1 during the 20% best days and 2.5 times of the value of 15.2 Mm-1 during the middle 60% days. Sulfate is the largest contributor to aerosol light extinction, with a contribution of 33% in the 20% worst days. OMC and Nitrate contributes 26% and 25% as well.
Figure 3 suggests that the highest occurrence of the 20% worst days happened in August, in which ~ 40% of the sampling days are the 20% haziest days at U. L. Bend Wilderness Area. As shown in Figure 4, sulfate is the largest aerosol contributor to haze during the 20% worst days from February to June and September to October, with a contribution of 30 - 40% during the 20% worst days. OMC is the largest aerosol contributor in July and August, and Nitrate is the largest one in November, December and January, with a contribution of 40 - 50% and 35 - 40%, respectively in the 20% worst days in those time periods.
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)
