INGA1 (Indian Gardens, AZ, Lat. 36.0776, Long. -112.1289, Alt. 1166)      

6 years aerosol data are available in Indian Gardens 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 ~ 140 Km; Deciview ~ 10.3). The average PM2.5 mass concentration is 4.2 mg/m3. The average contributions of the major aerosol components to Indian Gardens haze are particulate sulfate 19.6%, nitrate 4.6%, organic matter (OMC) 18.5%, elemental carbon (light absorbing carbon, LAC) 6.5%, fine soil 4.1% and coarse mass (CM) 11.0%. 

Bext = 28.0 Mm-1

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 30.6 Mm-1, which is about 3.6 times of the value of 8.4 Mm-1 during the 20% best days and 1.8 times of the value of 16.6 Mm-1 during the middle 60% days. OMC is the largest contributor to aerosol light extinction, with a contribution of 32% in the 20% worst days. Sulfate and CM also contribute 28% and 18%.

Figure 3 suggests that the highest occurrence of the 20% worst days happened in August, in which ~ 42% of the sampling days are the 20% haziest days at Indian Gardens. As shown in Figure 4, CM is the largest aerosol contributor to haze in the 20% worst days from April to June, with a contribution of ~ 25%. Sulfate is the largest aerosol contributor in January, April, July, August and December, with a contribution of ~ 22 - 42% in the worst days. OMC is the largest aerosol contributor for the rest of the year, with a contribution of ~ 23 - 36% 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)