Estimation of the contributions of long range transported aerosol in East Asia to carbonaceous aerosol and PM concentrations in Seoul, Korea using highly time resolved measurements: a PSCF model approach

Abstract

The contributions of long range transported aerosol in East Asia to carbonaceous aerosol and particulate matter (PM) concentrations in Seoul, Korea were estimated with potential source contribution function (PSCF) calculations. Carbonaceous aerosol (organic carbon (OC) and elemental carbon (EC)), PM(2.5), and PM(10) concentrations were measured from April 2007 to March 2008 in Seoul, Korea. The PSCF and concentration weighted trajectory (CWT) receptor models were used to identify the spatial source distributions of OC, EC, PM(2.5), and coarse particles. Heavily industrialized areas in Northeast China such as Harbin and Changchun and East China including the Pearl River Delta region, the Yangtze River Delta region, and the Beijing-Tianjin region were identified as high OC, EC and PM(2.5) source areas. The conditional PSCF analysis was introduced so as to distinguish the influence of aerosol transported from heavily polluted source areas on a receptor site from that transported from relatively clean areas. The source contributions estimated using the conditional PSCF analysis account for not only the aerosol concentrations of long range transported aerosols but also the number of transport days effective on the measurement site. Based on the proposed algorithm, the condition of airmass pathways was classified into two types: one condition where airmass passed over the source region (PS) and another condition where airmass did not pass over the source region (NPS). For most of the seasons during the measurement period, 249.5-366.2% higher OC, EC, PM(2.5), and coarse particle concentrations were observed at the measurement site under PS conditions than under NPS conditions. Seasonal variations in the concentrations of OC, EC, PM(2.5), and coarse particles under PS, NPS, and background aerosol conditions were quantified. The contributions of long range transported aerosols on the OC, EC, PM(2.5), and coarse particle concentrations during several Asian dust events were also estimated. We also investigated the performance of the PSCF results obtained from combining highly time resolved measurement data and backward trajectory calculations via comparison with those from data in low resolutions. Reduced tailing effects and the larger coverage over the area of interest were observed in the PSCF results obtained from using the highly time resolved data and trajectories.

Radiocarbon-based impact assessment of open biomass burning on regional carbonaceous aerosols in North China

“…Thus, to avoid uncertainties that can occur due to a limited amount of available data, an arbitrary weight function W(n ij ) as shown in Eq. (2) is multiplied with the PSCF value (Jeong et al, 2011).…”

Concentration-weighted trajectory approach to identifying potential sources of speciated atmospheric mercury at an urban coastal site in Nova Scotia, Canada

“…Model comparisons found comparable results when Concentration Fields (using logarithmic concentrations), CWT, and PSCF were applied to virtual sources and modeled concentrations (Kabashnikov et al, 2011). When applied to field carbonaceous aerosols and PM measurements, good agreement was attained between PSCF and CWT models (Jeong et al, 2011). Han et al (2007) conducted comparisons between PSCF and RTWC and found there were some differences in the source areas identified for total gaseous mercury concentrations.…”

“…unlikely for airflow to pass over a particular area). Known as the tailing effect, the few number of trajectory segment endpoints can lead to the false identification of source areas because the concentrations are uniformly weighted along a trajectory (Watson et al, 2008;Jeong et al, 2011). Although a minimum of 2 trajectory segment endpoints per grid cell seems like a small number, it is equivalent to two sets of 3 h Hg concentrations and trajectory residence times in the seasonal CWT calculation.…”

“…The CWT for GEM, GOM, and PBM for a particular grid cell (i, j ) is a measure of the source strength of a grid cell to the Dartmouth site and is determined as follows (Jeong et al, 2011;Kabashnikov et al, 2011):…”

“…The concentrations are not explicitly included in the PSCF calculation and there is no requirement on how many back trajectories need to be generated. Other studies suggested that PSCF may be omitting source areas that fall slightly below the concentration threshold (Wang et al, 2009;Jeong et al, 2011). Prior to determining the CWTs, back trajectories corresponding to the sampling cycle of each 3 h GEM, GOM, and PBM measurement were generated using the HYSPLIT4 model (Draxler and Rolph, 2012;Rolph, 2012).…”