Abstract
Abstract. Spatiotemporal characteristics of surface ozone (O3) variations over South Korea are investigated with consideration of meteorological factors and timescales based on the Kolmogorov–Zurbenko filter (KZ filter), using measurement data at 124 air quality monitoring sites and 72 weather stations for the 12 yr period of 1999–2010. In general, O3 levels at coastal cities are high due to dynamic effects of the sea breeze while those at the inland and Seoul Metropolitan Area (SMA) cities are low due to the NOx titration by local precursor emissions. We examine the meteorological influences on O3 using a combined analysis of the KZ filter and linear regressions between O3 and meteorological variables. We decomposed O3 time series at each site into short-term, seasonal, and long-term components by the KZ filter and regressed on meteorological variables. Impact of temperature on the O3 levels is significantly high in the highly populated SMA and inland region, but low in the coastal region. In particular, the probability of high O3 occurrence doubles with 4 °C of temperature increase in the SMA during high O3 months (May–October). This implies that those regions will experience frequent high O3 events in a future warming climate. In terms of short-term variation, the distribution of high O3 probability classified by wind direction shows the effect of both local precursor emissions and long-range transport from China. In terms of long-term variation, the O3 concentrations have increased by +0.26 ppbv yr−1 (parts per billion by volume) on nationwide average, but their trends show large spatial variability. Singular value decomposition analyses further reveal that the long-term temporal evolution of O3 is similar to that of nitrogen dioxide, although the spatial distribution of their trends is different. This study will be helpful as a reference for diagnostics and evaluation of regional- and local-scale O3 and climate simulations, and as a guide to appropriate O3 control policy in South Korea.
Highlights
Surface ozone (O3) is a well-known secondary air pollutant, which affects air quality, human health, and vegetation
It is estimated that approximately 27 % (0.29 Mt) of total nitrogen oxides (NOx) emissions and 34 % (0.30 Mt) of the volatile organic compound (VOC) emissions in South Korea were from the Seoul Metropolitan Area (SMA) in 2010 (KMOE, 2013)
This study has investigated various spatiotemporal features and the interrelationship of surface O3 and related meteorological variables over South Korea based on ground measurements for the period 1999–2010
Summary
Surface ozone (O3) is a well-known secondary air pollutant, which affects air quality, human health, and vegetation. The increasing trends of O3 in Europe, the North Atlantic, North America, and Japan have flattened over the past decade (Oltmans et al, 2006, 2013), there have still been concerns about elevated O3 concentrations in China owing to rapid economic growth and industrialization (Ding et al, 2008; Tang et al, 2009; Wang et al, 2009, 2012) Such recent increases of O3 in China can affect the regional background O3 levels in East Asia by transboundary transport of O3 and its precursors. Ordóñez et al (2005) showed that high temperature extremes probably led to the high occurrence of severe O3 episodes during the summer 2003 heat wave over Europe These results imply the potentially large sensitivity of O3 concentration and related air quality to the temperature increases (Jacob and Winner, 2009).
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