SENE1 (Seney NWR, MI, Lat. 46.2889, Long. -85.9503, Alt. 214.5)
Based on the regional haze rule version 2, 5 years of complete aerosol data are available in Seney NWR during the baseline period of 2000 - 2004. As shown in Figure 1, the overall average total light extinction coefficient (Bext) is 51.6 Mm-1 (Visual Range ~ 122 Km; Deciview ~ 14). The average PM2.5 mass concentration is 5.0 mg/m3. The average contributions of the major aerosol components to Seney haze are particulate sulfate 42.0%, nitrate 16.2%, organic matter (OMC) 11.8%, elemental carbon (light absorbing carbon, LAC) 3.7%, fine soil 0.5%, sea salt 0.2%, and coarse mass (CM) 2.3%.
Figure 1 Average contributions of major aerosol chemical components to light extinction (Based on data available in 2000-2004)
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 2000-2004)
As Figure 2 indicates, the average light extinction coefficient during the 20% worst days is 119.6 Mm-1, which is about 5.8 times of the value of 20.6 Mm-1 during the 20% best days and 3.1 times of the value of 38.8 Mm-1 during the middle 60% days. Sulfate is the largest aerosol contributor to light extinction during the 20% worst days, with a contribution of ~ 51%. Nitrate also contributes about 23% to light extinction during the 20% worst visibility days.
Figure 3 suggests that the highest occurrence of the 20% worst days happened in the summer from June to August, in which ~ 30% of the sampling days are the 20% haziest days at Seney. As shown in Figure 4, in the 20% worst visibility days, sulfate is the largest aerosol contributor to haze during the warm months (with a contribution of more than 60% from April to September), while nitrate is the largest contributor during the cold months (with a contribution of ~ 40 - 70% during January to March and November to December).
Figure 3 Percentage of sampling days that are 20% worst days in each month (Based on data available in 2000-2004)
Figure 4 Average contributions of major aerosol chemical components to light extinction during 20% worst days in each month (Based on data available in 2000-2004)
