PORE1 (Point Reyes National Seashore, CA, Lat. 38.1199, Long. -122.9122, Alt. 85) Print-Friendly Version Print-Friendly Version (B&W)
6 years aerosol data are available in Point Reyes National Seashore during the sampling period of 1997 - 2002. As shown in Figure 1, the overall average total light extinction coefficient (Bext) is 43.4 Mm-1 (Visual Range ~ 90 Km; Deciview ~ 14.7). The average PM2.5 mass concentration is 6.8 mg/m3. The average contributions of the major aerosol components to Point Reyes National Seashore haze are particulate sulfate 28.6%, nitrate 21.7%, organic matter (OMC) 11.3%, elemental carbon (light absorbing carbon, LAC) 3.1%, fine soil 0.5% and coarse mass (CM) 11.7%.
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 73.4 Mm-1, which is about 5.6 times of the value of 13.1 Mm-1 during the 20% best days and 2.8 times of the value of 26.1 Mm-1 during the middle 60% days. Nitrate is the largest contributor to aerosol light extinction, with a contribution of 42% in the 20% worst days. Sulfate also contributes 27% to the aerosol light extinction in the 20% worst days.
Figure 3 suggests that the highest occurrence of the 20% worst days happened in March, November, December and January, in which ~ 40% of the sampling days are the 20% haziest days at Point Reyes National Seashore. As shown in Figure 4, nitrate is the largest aerosol contributor to haze in the 20% worst days in the Winter time and May, with a contribution of ~ 50% in the Winter and ~30% in May. While sulfate is the largest aerosol contributor, with a contribution of 30 - 50%, to haze from March to October except May. CM also contribute ~32% to haze in the 20% worst days in June.
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)
