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 40.1 Mm^-1, which is about 6.2 times of the value of 6.5 Mm^-1 during the 20% best days and 1.9 times of the value of 21.0 Mm^-1 during the middle 60% days. Sulfate is the largest contributor to aerosol light extinction during the 20% worst days, and the contribution of sulfate to aerosol light extinction is  ~ 45% in worst days. OMC also contributes about 23% in the worst days.

Figure 3 suggests that the highest occurrence of the 20% worst days happened in October, in which ~ 40% of the sampling days are the 20% haziest days at Olympic National Park. As shown in Figure 4, sulfate is the largest aerosol contributor to haze the whole year except November, with a contribution of ~ 30 - 50% in the 20% worst days. Nitrate contributes ~ 30% to haze in the 20% worst days in November, and is the largest contributor to haze.

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)