Abstract. Together with emissions of air pollutants and precursors, meteorological
conditions play important roles in local air quality through accumulation or
ventilation, regional transport, and atmospheric chemistry. In this study, we
extensively investigated multi-timescale meteorological effects on the urban
air pollution using the long-term measurements data of PM10,
SO2, NO2, CO, and O3 and meteorological variables
over the period of 1999–2016 in Seoul, South Korea. The long-term air
quality data were decomposed into trend-free short-term components and
long-term trends by the Kolmogorov–Zurbenko filter, and the effects of
meteorology and emissions were quantitatively isolated using a multiple
linear regression with meteorological variables. In terms of short-term
variability, intercorrelations among the pollutants and meteorological
variables and composite analysis of synoptic meteorological fields exhibited
that the warm and stagnant conditions in the migratory high-pressure system
are related to the high PM10 and primary pollutant, while the strong
irradiance and low NO2 by high winds at the rear of a cyclone are
related to the high O3. In terms of long-term trends, decrease in
PM10 (−1.75 µg m−3 yr−1) and increase in
O3 (+0.88 ppb yr−1) in Seoul were largely contributed by
the meteorology-related trends (−0.94 µg m−3 yr−1 for
PM10 and +0.47 ppb yr−1 for O3), which were
attributable to the subregional-scale wind speed increase. Comparisons with
estimated local emissions and socioeconomic indices like gross domestic product (GDP) growth and fuel
consumptions indicate probable influences of the 2008 global economic
recession as well as the enforced regulations from the mid-2000s on the
emission-related trends of PM10 and other primary pollutants. Change
rates of local emissions and the transport term of long-term components
calculated by the tracer continuity equation revealed a decrease in
contributions of local emissions to the primary pollutants including
PM10 and an increase in contributions of local secondary productions to
O3. The present results not only reveal an important role of
synoptic meteorological conditions on the episodic air pollution events but
also give insights into the practical effects of environmental policies and
regulations on the long-term air pollution trends. As a complementary
approach to the chemical transport modeling, this study will provide a
scientific background for developing and improving effective air quality
management strategy in Seoul and its metropolitan area.
COASTAL CHANGES AT BETHANY BEACH, DELAWARE