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In this study, spatial and temporal variations of radiative forcing(RF) and mean temperature changes due to green-house gases(CO 2 , CH 4 , and N 2 O) emitted from commercial aircraft were examined based on the simplified expres-sion at the airports in Korea during 2009~2010. The radiative transfer model (SBDART) was used to comparewith the RF and mean temperature changes calculated from the simplified expressions for greenhouse gas CO 2 . TheRF simulated by the SBDART was about 67% higher than that of the simplified expression, on average. Thehighest mean RF(up to 9.0 mW/m 2 for CO 2 ) and mean temperature changes(up to 9.7×10 -5 �K/day for CO 2 ) for allGHGs occurred at Ulsan airport during the study period, whereas the lowest RF and temperature changes atYangyang (for CO 2 ) and Sacheon airports (for CH 4 and N 2 O). In the case of CH 4 and N 2 O, their effects to the RFand mean temperature change were negligible compared to CO 2 . Key words : Greenhouse gas emissions, Radiative forcing, Mean temperature change, Airport, Aircraft, Simplifiedexpression, Radiative transfer model, SBDART

Monthly variations of radiative forcing (RF) and mean temperature changes by greenhouse gases emitted from commercial aircraft were estimated based on the simplified expression at four international airports (Incheon, Gimpo, Jeju, and Gimhae Airports) during the years of 2009~2010. The highest RF and mean temperature change in the study area occurred at Incheon Airport, whereas the lowest RF and mean temperature change at Gimhae Airport. During 2009~2010, the mean RF and mean temperature change estimated from aircraft emissions at Incheon Airport were approximately 30.0 and , respectively. The mean RF and mean temperature changes caused by other greenhouse gas was significantly small ( and ). Meanwhile, emissions caused negative mean RF ( at Incheon Airport) and the decrease of mean temperature () due to consumption of atmospheric in the aircraft engine.

Emissions of air pollutants and greenhouse gases (GHGs) by aircraft at the Gimhae International Airport (GIA) were investigated using the Emissions and Dispersion Modeling System (EDMS) version 5.1.3. The number of Landing and Take-Off (LTO) at the GIA for aircraft B737 was dominant, accounting for more than 60% of the total LTOs. For air pollutant emissions, CO was the most dominant pollutant by aircraft, followed by , VOCs, , etc. The emissions of CO, , and VOCs in 2009 (and 2010) at the GIA were 974 (968), 447 (433), 118 (122) ton/yr, respectively. The emissions of GHGs such as , , and in 2009 (and 2010) were 110,795 (111,114), -0.157 (-0.151), and 1,989 (1,998) ton/yr, respectively. The negative number in emission represents the consumption of atmospheric in the engine. In addition, the emissions of most air pollutants (except for ) and GHGs were estimated to be high in Taxi-Out and Climb-Out modes.

In this study, a series of experiments were carried out to measure temporal stability of reduced sulfur compounds (RSCs) in Tedlar bag samples as a function of elapsed storage time. To this end, temporal variability of 4 RSC standard gases (, , DMS, DMDS) was measured up to 29 days. For the purpose of comparison, RSC samples were stored in both individual and mixed state. In the case of mixed standard, samples were also examined to allow comparison between light and dark condition. Then results of data were the most stable with the least change in its concentrations through the end of exps (29 days). When compared with previous studies, the extent of stability appeared to be influenced by the initial concentration levels of samples. When the patterns were compared between individual and mixture samples, differences were not significant in the case of and DMS. The effects of light conditions on temporal stability were seen to be fairly sensitive on most RSC other than . The results of our study confirm that the stability of RSC storage is affected by their involvement in photochemical reactions.

Photochemical characteristics of ozone () and its precursors such as budget and -VOC sensitivity were analyzed in different physico-chemical properties of air masses around the Mexico City Metropolitan Area (MCMA) using aircraft observations during March 2006. The physico-chemical properties of air masses were categorized into 5 groups: boundary layer (BL), biomass burning (BB), free tropospheric continent (FTCO) and marine (FTMA), and Tula industrial complex (TIC). Results from the budget analysis indicated that production for BL, FTCO, and FTMA (for BB and TIC) was mainly controlled by a photochemical production pathway, a reaction of NO with (with ), while the main pathway of photochemical destruction for BL, FTCO, and FTMA (for BB and TIC) was a reaction of with (of with (D)). In addition, most of air mass categories (especially FTCO) were estimated to be -sensitive for production with lower , higher ratios of the other indicator species (e.g., ), , etc.), and the lower removal rate of radicals (0.5) by the reaction of OH with than those of the VOC-sensitive condition.

We examined high ozone episodes observed during the intensive measurement periods (11 May~21 June and 30 July~11 August 2009) in the Gulf of Gwangyang. During that period, there were a few events (or days) in which 1 hr averaged ozone concentrations were greater than 100 ppbv. The analysis of ozone budget and photochemical characteristics related to the ozone production was carried out using a photochemical box model. Ozone sensitivity to and VOCs was also examined in the study area during the measurement period. Diurnal variation of ozone during the episodes was similar to that of odd hydrogen radicals (, and ), suggesting significant correlation with photochemical production of ozone during the episodes. In general, ozone concentration in the study area during the measurement period was sensitive to VOCs, whereas ozone was sensitive to under certain conditions. Ozone sensitivity assessment using a radical budget analysis and /VOCs-control strategy was consistent with that using indicator species ( ratio).