본 연구는 서울광역도시권에서 나타나는 도시 스프롤과 통근 패턴간에 어떤 관계가 있는지 분석하는 것을 목적으로 한다. 선행 연구에서 산출된 스프롤 지수들과 사회경제적 특성을 나타내는 주요 지표들을 설명변수로 하고, 자가용 통근시 평균 운전 시간과 대중교통이용 통근자 비율을 종속변수로 하여 두 가지의 회귀모형을 구성하였다. OLS 분석에 비해 GWR 분석에서 모형의 설명력과 적합도가 개선되었으며, 설명변수 중 밀도의 영향력이 가장 큰 것으로 나타났다. 또한 GWR 분석에 의해 전역적 모형에서 는 유의하지 않았으나 국지적으로는 유의하게 나타나는 다양한 설명변수들을 확인할 수 있었다.

This study analyzed the characteristics of high PM2.5 episodes that meets the concentration criteria of Emergency Reduction Measures Plan (ERMP) in Busan during the 2015-2020, and compared with those in Seoul. As a first step, the CAPSS-2017 emission data was employed to analyze the emission differences between Busan and Seoul, and pointed out that Busan emission included the dominance of ship emissions (37.7%) among total PM2.5 city emissions, whereas fugitive PM2,5 emission was the highest in Seoul. These emission characteristics are indicating that the controlling action plan should be uniquely applied to cope with ERMP in each region. We selected extremely high PM2.5 episode days that meet the criteria of ERMP levels. In Busan, Ulsan, and Gyeongnam region, 15, 16, and 8 days of extremely high PM2.5 cases were found, respectively, whereas Seoul showed approximately doubling of occurrences with 37 cases. However, the occurrences in summer season indicated big differences between two cities: the proportion of summer-season occurrence was 13-25% in Busan, whereas no single case have occurred in Seoul. This is suggesting the needs of comprehensive summer emission reduction plan with focusing on sulfur reduction to effectively cope with the ERMP levels in summer in the southeastern region, including Busan.

A comparison of ozone simulations in the seoul metropolitan region (SMR) using the community multiscale air quality (CMAQ) model with SAPRC99 and CB05 chemical mechanisms (i.e. EXP-SP99 and EXP-CB05) has been conducted during four seasons of 2012. The model results showed that the differences in average ozone concentrations between the EXP-SP99 and EXP-CB05 were found to be large in summer, but very small in the other seasons. This can be attributed that the SAPRC99 tends to produce more ozone than the CB05 in urban area like the SMR with low VOC/NOx ratio under high ozone conditions. Through quantitative comparison between two mechanisms for the summer, it was found that the average ozone concentrations from the EXP-SP99 were about 3 ppb higher than those from the EXP-CB05 and agreed well with the observations. Horizontal differences in ozone concentrations between SAPRC99 and CB05 showed that significant differences were found in southern part of the SMR and over the sea near the coast in summer.

In order to improve the prediction of the regional air quality modeling in the Seoul metropolitan area, a sensitivity analysis using two PBL and microphysics (MP) options of the WRF model was performed during four seasons. The results from four sets of the simulation experiments (EXPs) showed that meteorological variables (especially wind field) were highly sensitive to the choice of PBL options (YSU or MYJ) and no significant differences were found depending on MP options (WDM6 or Morrison) regardless of specific time periods, i.e. day and night, during four seasons. Consequently, the EXPs being composed of YSU PBL option were identified to produce better results for meteorological elements (especially wind field) regardless of seasons. On the other hand, the accuracy of all simulations for summer and winter was somewhat lower than those for spring and autumn and the effect according to physics options was highly volatile by geographical characteristics of the observation site.

In this study, the regional climate (WRF) and air quality (CMAQ) models were used to simulate the effects of future urban growth on surface ozone concentrations in the Seoul metropolitan region (SMR). These analyses were performed based on changes in ozone concentrations during ozone seasons (May–June) for the year 2050 (future) relative to 2012 (present) by urban growth. The results were compared with the impacts of RCP scenarios on ozone concentrations in the SMR. The fractions of urban in the SMR (25.8 %) for the 2050 were much higher than those (13.9 %) for the 2012 and the future emissions (e.g., CO, NO, NO2, SO2, VOC) were increased from 121 % (NO) to 161.3 % (NO2) depending on emission material. The mean and daily maximum 1-h ozone in the SMR increased about 3 - 7 ppb by the effect the RCP scenarios. However, the effect of urban growth reduced the mean ozone by 3 ppb in the SMR and increased the daily maximum 1-h ozone by 2 - 5 ppb over the northeastern SMR and around the coastline. In particular, the ozone pollution days exceeding the 1-h regulatory standard (100 ppb) were far more affected by urban growth than mean values. As a result, the average number of days exceeding the 1-h regulatory standard increased up to 10 times.