The Influence of Meteorological Conditions and Complex Topography on Ozone Concentrations in a Valley Area near Coastal Metropolitan Cities

Abstract

The influences of meteorological conditions and complex topography on ozone (O 3 ) concentrations were evaluated at two different sites [Jung Ang (JA): a semi-closed topography and Seo Chang (SC): a closed topography] within a valley city neighboring coastal metropolitan cities (Busan and Ulsan) during days exhibiting high O 3 episodes (8 and 10 August 2006), using the MM5-CMAQ modeling system. The contributions of physical and chemical processes to the O 3 concentrations were also assessed within the mixed layers of the two sites (JA and SC) during the study period. High O 3 concentrations at site JA on 8 August were the result of combined effects of the horizontal transport (in a north-south direction) of O 3 and its precursors and their subsequent reaction with southerly (from Busan) and easterly sea breezes (from Ulsan) and their accumulation due to the convergence of these sea breezes. Such O 3 enhancements on 10 August were caused mainly by the vertical transport of O 3 and its precursors and partly by their accumulation (from local emission sources) due to weak winds. Unlike site JA, the O 3 enhancement at site SC on 8 August was mainly ascribable to horizontal transport (in an east-west direction) from the source regions of Ulsan. On 10 August, vertical transport of downslope flows from the top of mountains largely contributed to O 3 concentrations. In addition, the heights of maximum O 3 inflow due to horizontal or vertical transport between the two sites during the episodes were different depending on the differences in the heights of mountains and/or the movement directions and intensities of sea breezes.

A Case Study of Energy Deposition and Absorption by Magnetic Cloud Electrons and Protons over the High Latitude Stations: Effects on the Mesosphere and Lower Thermosphere

“…Such perturbation induces chemical heating rates and infrared cooling. Precipitating particles produce forms of odd nitrogen (NO x ) and odd Hydrogen (HO x ) (Swider and Kenesha 1973;Rusch et al 1981;Solomon et al 1981;Saetre et al 2004;Rodger et al 2010b;Kang et al 2012) which undergo a series of chemical reactions. Although minor gases, if they enter the uppermost layer of the stratosphere and troposphere, they contribute to the overall processes that catalytically deplete ozone (Grenfell et al 2006) and partly affect the radiation budget of the polar atmosphere.…”

Impacts of Detailed Land-Use Types and Urban Heat in an Urban Canopy Model on Local Meteorology and Ozone Levels for Air Quality Modeling in a Coastal City, Korea

“…Integrated processes rate (IPR) analysis was applied to quantify the UCM contribution to the physical and chemical processes relating to the predicted O 3 concentrations. The IPR O 3 concentration analysis includes examinations of the rates of gas-phase chemical production, horizontal transport, vertical transport, and dry deposition leading to net changes in O 3 concentrations (Wang et al 2010;Song et al 2011;Kang et al 2012). Busan was classified into three areas to assess the detailed contribution of the UCM under different urban and geographic conditions, such as urban or suburban, and coastal or inland areas: the urban coastal area (UCA), the urban downtown area (UDT), and suburban area (SUB), as shown in Fig.…”