MORA1 (Mount Rainier National Park, WA, Lat. 46.7579, Long. -122.1225, Alt. 427)

6 years aerosol data are available in Mount Rainier National Park during the sampling period of 1997 - 2002. As shown in Figure 1, the overall average total light extinction coefficient (Bext) is 37.9 Mm-1 (Visual Range ~ 103 Km; Deciview ~ 13.3). The average PM2.5 mass concentration is 4.1 mg/m3. The average contributions of the major aerosol components to Mount Rainier National Park haze are particulate sulfate 36.4%, nitrate 6.6%, organic matter (OMC) 18.6%, elemental carbon (light absorbing carbon, LAC) 7.5%, fine soil 0.6% and coarse mass (CM) 4.0%. 

Bext = 37.9 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)

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As Figure 2 indicates, the average aerosol light extinction coefficient (Bext – Rayleigh Scattering (10 Mm-1)) during the 20% worst days is 56.4 Mm-1, which is about 8.4 times of the value of 6.7 Mm-1 during the 20% best days and 2.2 times of the value of 25.1 Mm-1 during the middle 60% days. Sulfate is the largest contributor to aerosol light extinction, with a contribution of 52% in the 20% worst days.

Figure 3 suggests that the highest occurrence of the 20% worst days happened in July and August during which about 50% of the sampling days are the 20% haziest days at Mount Rainier National Park.  As shown in Figure 4, during this time period, sulfate is the largest aerosol contributor to haze, with a contribution of ~ 50% during the 20% worst days. OMC is the second biggest contributor to haze in this time period, with a contributions of ~ 20%.  Sulfate is the largest aerosol contributor to haze except November, with a contribution of 30 - 50% in the worst days. OMC is the largest one in November, with a contribution of 33% in the worst days, though the occurrence of worst days is pretty low in this month.

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)