Spectral optical properties of long-range transport Asian dust and pollution aerosols over Northeast Asia in 2007 and 2008

Abstract

Abstract. As a part of the IGAC (International Global Atmospheric Chemistry) Mega-cities program, aerosol physical and optical properties were continuously measured from March 2007 to March 2008 at an urban site (37.57 • N, 126.94 • E) in Seoul, Korea. Spectral optical properties of long-range transported Asian dust and pollution aerosols have been investigated based on the year long measurement data. Optically measured black carbon/thermally measured elemental carbon (BC/EC) ratio showed clear monthly variation with high values in summer and low values in winter mainly due to the enhancement of light attenuation by the internal mixing of EC. Novel approach has been suggested to retrieve the spectral light absorption coefficient (b abs ) from Aethalometer raw data by using BC/EC ratio. Mass absorption efficiency, σ abs (= b abs /EC) at 550 nm was determined to be 9.0±1.3, 8.9±1.5, 9.5±2.0, and 10.3±1.7 m 2 g −1 in spring, summer, fall, and winter, respectively with an annual mean of 9.4±1.8 m 2 g −1 . Threshold values to classify severe haze events were suggested in this study. Increasing trend of aerosol single scattering albedo (SSA) with wavelength was observed during Asian dust events while little spectral dependence of SSA was observed during long-range transport pollution (LTP) events. Satellite aerosol optical thickness (AOT) and Hysplit air mass backward trajectory analyses as well as chemical analysis were performed to characterize the dependence of spectral optical properties on aerosol type. Results from this study can provide useful information for studies on regional air quality and aerosol's effects on climate change.

LIVAS: a 3-D multi-wavelength aerosol/cloud database based on CALIPSO and EARLINET

“…The spectral dependence and range of LIVAS SSA values are similar to the values provided in the Dubovik et al (2002) climatology and references therein, whereas the CALIPSO SSA has lower values which also agree with other studies (e.g., Eck et al, 1998Eck et al, , 2003. The polluted dust SSA spectral dependence is similar for both models but different to that of dust mixtures with smoke and pollution presented in the literature (e.g., Jung et al, 2010;Holler et al, 2003). Finally, the clean marine SSA for both models agrees very well with other studies in the literature (e.g., Dubovik et al, 2002;Hasekamp et al, 2011).…”

“…For the dust type, the LIVAS size distribution has fewer fine particles than the CALIPSO model, in agreement with the AERONET climatology of Dubovik et al (2002) and findings of experimental campaigns dedicated to mineral dust characterization (e.g., McConnell et al, 2008;Weinzierl et al, 2009;Müller et al, 2011;Toledano et al, 2011). For the polluted dust type both models seem to fall within the range of the large variability reported in the literature for dusty mixtures (Eck et al, 1999;Jung et al, 2010). The more pronounced fine mode in the LIVAS model resembles the size distributions of dust and pollution mixtures .…”

Impact of Siberian forest fires on the atmosphere over the Korean Peninsula during summer 2014

“…The sampled aerosol was then passed through a multichannel parallel-plate denuder with a carbon-impregnated filter to remove semivolatile organic vapors, and then collected on a quartzfiber filter. The sampled aerosol was analyzed based on the thermal-optical transmittance (TOT) protocol for pyrolysis correction and the NIOSH (National Institute for Occupational Safety and Health) method 5040 temperature profile (Birch and Cary, 1996;Jung et al, 2010). External calibration was performed using known amounts of sucrose.…”

Ground-based characterization of aerosol spectral optical properties of haze and Asian dust episodes under Asian continental outflow during winter 2014

“…The ω measured by ground-based remote sensing (0.9-0.93) is ∼ 10 % higher than values measured at the surface (0.8-0.9) (Cheng et al, 2015). From one year's worth of observations in Seoul, South Korea, a trend of increasing ω with wavelength was observed during Asian dust events, whereas little spectral dependence of ω was observed during LRT haze events (Jung et al, 2010). During the Campaign of Air Quality Research in Beijing 2006(CAREBeijing-2006, ω was found to be closely related to the inflow of air to Beijing.…”