Cluster analysis of diurnal variations in BC concentration from Multi-Angle Absorption Photometer

Black carbon (BC) is emitted from incomplete combustion of carbon-containing fuels, such as fossil fuels (diesel and coal) and biomass burning (forest fires and burning of agricultural waste). We have measured BC concentration using MAAP (Multi-Angle Absorption Photometer, Model 5012, Thermo Scientific) during the past few years. The measurement site is on the rooftop of the five-story building on the hill (37.02 °N, 127.16 °E, 167 m above sea level), about 35 km southeast of Seoul; there are no major emission sources nearby except a 4-lane road running about 1.4 km to the west. Previous studies reveal that the effects of vehicle emissions are not as direct as urban sites but those of biomass burning are general. Diurnal variations of BC concentration are classified using cluster analysis. Typical patterns are determined to identify the primary emissions and their effects on the concentration level. High concentration episodes are discriminated and major factors that influence the evolution of the episodes are investigated.