BRCA1 (Bryce Canyon National Park, UT, Lat. 37.6184, Long. -112.1735, Alt. 2477)

6 years aerosol data are available in Bryce Canyon National Park during the sampling period of 1997 - 2002. As shown in Figure 1, the overall average total light extinction coefficient (Bext) is 23.1 Mm-1 (Visual Range ~ 169 Km; Deciview ~ 8.4). The average PM2.5 mass concentration is 2.9 mg/m3. The average contributions of the major aerosol components to Bryce Canyon National Park haze are particulate sulfate 18.2%, nitrate 6.4%, organic matter (OMC) 16.2%, elemental carbon (light absorbing carbon, LAC) 5.1%, fine soil 2.4% and coarse mass (CM) 8.3%. 

Bext = 23.1 Mm-1

 

Figure 1 Average contributions of major aerosol chemical components to light extinction (1997-2002)  

 

Figure 2 Average contributions of major aerosol chemical components to light extinction in 20% best, middle 60% and 20% worst days (1997-2002)

As Figure 2 indicates, the average aerosol light extinction coefficient (Bext – Rayleigh Scattering (10 Mm-1)) during the 20% worst days is 24.1 Mm-1, which is about 4.7 times of the value of 5.2 Mm-1 during the 20% best days and 2.0 times of the value of 11.8 Mm-1 during the middle 60% days. Organic matter and sulfate are two of the largest contributors to aerosol light extinction during the 20% worst days, and the contribution of OMC and sulfate to aerosol light extinction are  ~ 35.6% and 26.9%, respectively in worst days.

Figure 3 suggests that the highest occurrence of the 20% worst days happened in May, July and August, in which ~35% of the sampling days are the 20% haziest days at Bryce Canyon National Park. As shown in Figure 4, OMC is the largest aerosol contributor to haze from May to September with a contribution of 30%. Sulfate contributes ~10 - 30% to haze throughout the year, while nitrate dominates in December and January.

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Figure 3 Percentage of sampling days that are 20% worst days in each month (1997-2002)

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Figure 4 Average contributions of major aerosol chemical components to light extinction during 20% worst days in each month (1997-2002)