SACR1 (Salt Creek, NM, Lat. 33.4597, Long. -104.4042, Alt. 1077)
2 year and 9 month aerosol data are available in Salt Creek during the sampling period of 1997 - 2002. As shown in Figure 1, the overall average total light extinction coefficient (Bext) is 39.6 Mm-1 (Visual Range ~ 98 Km; Deciview ~ 13.8). The average PM2.5 mass concentration is 5.8 mg/m3. The average contributions of the major aerosol components to Salt Creek haze are particulate sulfate 25.7%, nitrate 13.7%, organic matter (OMC) 11.4%, elemental carbon (light absorbing carbon, LAC) 4.5%, fine soil 3.2% and coarse mass (CM) 16.2%.
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 50.2 Mm-1, which is about 3.5 times of the value of 14.2 Mm-1 during the 20% best days and 1.8 times of the value of 27.7 Mm-1 during the middle 60% days. Sulfate is the largest contributor to aerosol light extinction, with a contribution of 38% in the 20% worst days. CM and nitrate also contribute about 20% to the aerosol light extinction in the 20% worst days.
Figure 3 suggests that the highest occurrence of the 20% worst days happened in April and September, in which ~ 40% of the sampling days are the 20% haziest days at Salt Creek. As shown in Figure 4, in the spring and early summer, CM and sulfate are two of the largest aerosol contributors to haze in the 20% worst days with a contributions of 30% and 25%, respectively. Nitrate and sulfate are two of the largest aerosol contributor to haze in the 20% worst days in November, December, January and February, with a contribution of 20 - 45% and 20 - 30%, respectively. Sulfate is the largest aerosol contributor to haze in the summer and early fall, with a contribution of 40 - 45%.
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)