SIME1 (Simeonof Wilderness Area, AK, Lat. 55.3477, Long. -160.4885, Alt. 30)
11 months aerosol data are available in Simeonof Wilderness Area during the sampling period of 1997 - 2002. As shown in Figure 1, the overall average total light extinction coefficient (Bext) is 29.8 Mm-1 (Visual Range ~ 131 Km; Deciview ~ 10.9). The average PM2.5 mass concentration is 3.8 mg/m3. The average contributions of the major aerosol components to Simeonof Wilderness Area haze are particulate sulfate 40.4%, nitrate 4.8%, organic matter (OMC) 8.5%, elemental carbon (light absorbing carbon, LAC) 3.6%, fine soil 0.6% and coarse mass (CM) 8.6%.
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 36.8 Mm-1, which is about 5.1 times of the value of 7.2 Mm-1 during the 20% best days and 2.0 times of the value of 18.4 Mm-1 during the middle 60% days. Sulfate 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 March, April and June, in which ~ 40% of the sampling days are the 20% haziest days at Simeonof Wilderness Area. As shown in Figure 4, sulfate is the largest aerosol contributor to haze during the 20% worst days throughout the year.
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)