GICL1 (Gila Wilderness, NM, Lat. 33.2204, Long. -108.235, Alt. 1776)
6 years aerosol data are available in Gila Wilderness during the sampling period of 1997 - 2002. As shown in Figure 1, the overall average total light extinction coefficient (Bext) is 27.1 Mm-1 (Visual Range ~ 144 Km; Deciview ~ 10.0). The average PM2.5 mass concentration is 4.0 mg/m3. The average contributions of the major aerosol components to Gila Wilderness haze are particulate sulfate 21.9%, nitrate 2.5%, organic matter (OMC) 20.7%, elemental carbon (light absorbing carbon, LAC) 6.7%, fine soil 2.7% 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 33.8 Mm-1, which is about 5.0 times of the value of 6.7 Mm-1 during the 20% best days and 2.3 times of the value of 14.7 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 ~ 41.5% in worst days. Sulfate also contributes 29.5% to aerosol light extinction.
Figure 3 suggests that the highest occurrence of the 20% worst days happened in July and August, in which ~50% of the sampling days are the 20% haziest days at Gila Wilderness. As shown in Figure 4, OMC and sulfate are two of the largest aerosol contributors to haze in July and August, 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)