SIAN1 (Sierra Ancha, AZ, Lat. 34.0909, Long. -110.9419, Alt. 1595) Print-Friendly Version Print-Friendly Version (B&W)
2 year and 9 month aerosol data are available in Sierra Ancha during the sampling period of 1997 - 2002. As shown in Figure 1, the overall average total light extinction coefficient (Bext) is 28.9 Mm-1 (Visual Range ~ 135 Km; Deciview ~ 10.6). The average PM2.5 mass concentration is 4.5 mg/m3. The average contributions of the major aerosol components to Sierra Ancha haze are particulate sulfate 18.1%, nitrate 5.6%, organic matter (OMC) 19.8%, elemental carbon (light absorbing carbon, LAC) 6.4%, fine soil 4.2% and coarse mass (CM) 11.4%.
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 30.4 Mm-1, which is about 3.1 times of the value of 9.8 Mm-1 during the 20% best days and 1.7 times of the value of 18.1 Mm-1 during the middle 60% days. OMC is the largest contributor to aerosol light extinction, with a contribution of 31% in the 20% worst days. Sulfate and CM also contribute 26% and 20%.
Figure 3 suggests that the highest occurrence of the 20% worst days happened in July and August, in which ~ 36% of the sampling days are the 20% haziest days at Sierra Ancha. As shown in Figure 4, OMC and sulfate each contributes ~ 20 - 30% to haze in the 20% worst days from July to December except October. CM is the largest aerosol contributor in October, with a contribution of 31%. Nitrate is the largest aerosol contributor to haze in January and February. OMC and CM are two of the largest aerosol contributors from April to June, with a contribution of ~ 25% and 20%, respectively.
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)
