Contribution of long-range transported aerosols to aerosol optical and physical properties: 3-year measurements at Gosan, Korea

Abstract:

Recently, more attentions have been paid to air quality in East Asia due to the enhanced loading of atmospheric pollutants related to rapid industrialization. Gosan Climate Observatory (GCO), Korea is regarded as an ideal site to study the transport of atmospheric pollutants because it is frequently influenced by various airmasses from China, Korea, Japan and Pacific Ocean. In order to understand aerosol optical and physical properties according to airmass transport routes, three-year (2012-2014) continuous measurements of aerosol scattering/absorption coefficient and number size distribution were analyzed, together with 48-hour backward trajectory calculations. The averaged aerosol absorption (σ_a) and scattering coefficient (σ_s) for airmasses transported from North China (NC; 36% of all trajectories) were 6.65 Mm^-1 and 94.72 Mm^-1 at 550 nm wavelength, respectively, which were similar to those for stagnant airmasses (ST; 22% of all trajectories; σ_a: 6.26 Mm^-1, σ_s: 93.99 Mm^-1). The highest values of σ_a (7.03 Mm^-1) and σ_s (108.34 Mm^-1) were observed when airmasses were traveled from South China (SC; 11% of all trajectories). σ_a and σ_s for airmasses from Korean Peninsula (KP; 7% of all trajectories) and Pacific Ocean (PO; 14% of all trajectories; in parenthesis) were 5.63 (2.76) Mm^-1 and 73.63 (50.93) Mm^-1, respectively. Compared to other airmasses, the higher values of Scattering Angstrom Exponent (SAE) for ST (1.65) is thought to be the build-up of anthropogenic fine particulate pollutants. The Absorption Angstrom Exponent (AAE) was estimated to be 1.32 for NC airmass and 1.02 for SC airmass. Over the study period, 130 days of total 557 days were identified as new particle formation and growth event (NPF) from Scanning Mobility Particle Sizer (SMPS) measurements by Cyclostationary Empirical Orthogonal Function (CSEOF) approach. Especially, 55.4% (72 days) of total 130 NPF days were found when a cold and dry airmass comes from NC after passing the frontal system.Recently, more attentions have been paid to air quality in East Asia due to the enhanced loading of atmospheric pollutants related to rapid industrialization. Gosan Climate Observatory (GCO), Korea is regarded as an ideal site to study the transport of atmospheric pollutants because it is frequently influenced by various airmasses from China, Korea, Japan and Pacific Ocean. In order to understand aerosol optical and physical properties according to airmass transport routes, three-year (2012-2014) continuous measurements of aerosol scattering/absorption coefficient and number size distribution were analyzed, together with 48-hour backward trajectory calculations. The averaged aerosol absorption (σ_a) and scattering coefficient (σ_s) for airmasses transported from North China (NC; 36% of all trajectories) were 6.65 Mm^-1 and 94.72 Mm^-1 at 550 nm wavelength, respectively, which were similar to those for stagnant airmasses (ST; 22% of all trajectories; σ_a: 6.26 Mm^-1, σ_s: 93.99 Mm^-1). The highest values of σ_a (7.03 Mm^-1) and σ_s (108.34 Mm^-1) were observed when airmasses were traveled from South China (SC; 11% of all trajectories). σ_a and σ_s for airmasses from Korean Peninsula (KP; 7% of all trajectories) and Pacific Ocean (PO; 14% of all trajectories; in parenthesis) were 5.63 (2.76) Mm^-1 and 73.63 (50.93) Mm^-1, respectively. Compared to other airmasses, the higher values of Scattering Angstrom Exponent (SAE) for ST (1.65) is thought to be the build-up of anthropogenic fine particulate pollutants. The Absorption Angstrom Exponent (AAE) was estimated to be 1.32 for NC airmass and 1.02 for SC airmass. Over the study period, 130 days of total 557 days were identified as new particle formation and growth event (NPF) from Scanning Mobility Particle Sizer (SMPS) measurements by Cyclostationary Empirical Orthogonal Function (CSEOF) approach. Especially, 55.4% (72 days) of total 130 NPF days were found when a cold and dry airmass comes from NC after passing the frontal system.