SPOK1 (Spokane Res., WA, Lat. 47.9045, Long. -117.8609, Alt. 548) Print-Friendly Version Print-Friendly Version (B&W)
1year and 4 month aerosol data are available in Spokane Res. during the sampling period of 1997 - 2002. As shown in Figure 1, the overall average total light extinction coefficient (Bext) is 48.9 Mm-1 (Visual Range ~ 80 Km; Deciview ~ 15.9). The average PM2.5 mass concentration is 7.0 mg/m3. The average contributions of the major aerosol components to Spokane Res. haze are particulate sulfate 16.9%, nitrate 12.5%, organic matter (OMC) 28.6%, elemental carbon (light absorbing carbon, LAC) 7.2%, fine soil 4.1% and coarse mass (CM) 10.2%.
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 75.5 Mm-1, which is about 4.9 times of the value of 15.5 Mm-1 during the 20% best days and 2.2 times of the value of 33.6 Mm-1 during the middle 60% days. OMC is the largest contributor to aerosol light extinction, with a contribution of 41% in the 20% worst days.
Figure 3 suggests that the highest occurrence of the 20% worst days happened in November and December, in which ~ 50 - 60% of the sampling days are the 20% haziest days at Spokane Res.. As shown in Figure 4, OMC is the largest aerosol contributor to haze during the 20% worst days the whole year except February and May. Nitrate and CM are the largest aerosol contributors to haze in the 20% worst days in February and May, respectively.
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)
