Characteristics of Aerosol Extinction Coefficient in Taipei Metropolitan Atmosphere

Abstract

The object of this study investigated the correlation of visibility with aerosol physical properties in the urban atmosphere. The field experiments were conducted in four seasons from August 2010 to March 2011 in National Taipei University of Technology (NTUT), located in the downtown of Taipei city. Integrating nephelometer was used to measure the aerosol optical properties and compared with the calculated values based upon the measurements of aerosol concentration and size distribution. The characterization of visibility was influenced by aerosol concentrations and relative humidity. When the relative humidity was above 70%, the particles usually grew into larger size range and changed their optical characteristics. The results showed that the surface area concentration had a great relationship with extinction coefficient, especially for PM 2.5 . The correlation between particle number or volume concentration and extinction coefficient was complicated. Hence, visibility could be estimated by particle surface area concentration. The conclusions suggested that particle surface area concentration obtained from number concentration combined with size distribution could be used to estimate visibility.

Metallic characteristics of PM2.5 and PM2.5-10 for clustered Aeolian Dust Episodes occurred in an extensive fluvial basin during rainy season

“…Suspended PMs in the atmosphere play a vital role on the physical, chemical, and optical effects, such as ambient air quality, atmospheric visibility, and radiative forcing (Claiborn et al 2011;Tsai et al 2010;. Poor atmospheric visibility is highly related to PMs, resulting from the extinction of visible light by fine particles (Cheng et al 2015). Moreover, such natural fugitive dust could also cause health problems if fine particles existed in connection with coarse particles suspended in the air.…”

The Horizontal and Vertical Characteristics of Aeolian Dust from Riverbed

“…Several studies reported that the atmospheric visibility is related to PM (Pillai et al, 2002;Pui et al, 2014;Cheng et al, 2015). The higher the particle mass concentration is, the poorer the visibility is (Kim et al, 2001;De et al, 2005;Cheng et al, 2015). At the same time, dust emission also influences the regional air quality and bring about human health problems (Ono, 2006;Goudie, 2009;Rashki et al, 2013;Goudie, 2014), especially, the contaminants along with dust affect human health as its transport to the densely populated town or city.…”

“…In general, pool visibility is essentially assigned to the extinction of visible light by particles (Friedlander, 2000). Several studies reported that the atmospheric visibility is related to PM (Pillai et al, 2002;Pui et al, 2014;Cheng et al, 2015). The higher the particle mass concentration is, the poorer the visibility is (Kim et al, 2001;De et al, 2005;Cheng et al, 2015).…”