Effect of an Urban Thermal Environment on the Air Quality in Two Cities

이귀옥,정우식,Hwa Woon Lee,Hyun-ju Lee,박종길 한국대기환경학회 2011 Asian Journal of Atmospheric Environment (AJAE) Vol.5 No.1

In this study, the effects of an urban thermal environment on air quality were investigated using hourly surface weather observation data and air quality data over six summers from 2000 to 2005 in two cities on the Korean Peninsula. One, the city of Daegu, is representative of basin topography and the other, the city of Busan, represents a coastal area. It is known that the characteristics of an urban thermal environment are represented as an “urban heat island”. Here, we focus on the nighttime urban thermal environment, which is called a “tropical night”, during the summer. On tropical nights in Busan, the temperature and cloud cover levels were higher than on non-tropical nights. Wind speed did not appear to make a difference even on a tropical night. However, the frequency of southwestern winds from the sea was higher during tropical nights. The prevailing southwest winds in all areas meant an inflow of air from the sea. So at most of the air quality stations, the ozone concentration during tropical nights was lower than during non-tropical nights. In Daegu, the tropical nights had higher temperatures and cloud covers. Despite these higher temperatures,the ozone concentration during the tropical nights was lower than that on non-tropical nights at most of the air quality stations. This feature was caused by low irradiance, which in turn caused an increased cloud cover. Wind speed was stronger during the tropical nights and dispersed the air pollutants. These meteorological characteristics of the tropical nights reduced ozone concentrations in the Daegu Basin.

Effect of an Urban Thermal Environment on the Air Quality in Two Cities

Lee, Kwi-Ok,Lee, Hwa-Woon,Lee, Hyun-Ju,Park, Jong-Kil,Jung, Woo-Sik Korean Society for Atmospheric Environment 2011 Asian Journal of Atmospheric Environment (AJAE) Vol.5 No.1

In this study, the effects of an urban thermal environment on air quality were investigated using hourly surface weather observation data and air quality data over six summers from 2000 to 2005 in two cities on the Korean Peninsula. One, the city of Daegu, is representative of basin topography and the other, the city of Busan, represents a coastal area. It is known that the characteristics of an urban thermal environment are represented as an "urban heat island". Here, we focus on the nighttime urban thermal environment, which is called a "tropical night", during the summer. On tropical nights in Busan, the temperature and cloud cover levels were higher than on non-tropical nights. Wind speed did not appear to make a difference even on a tropical night. However, the frequency of southwestern winds from the sea was higher during tropical nights. The prevailing southwest winds in all areas meant an inflow of air from the sea. So at most of the air quality stations, the ozone concentration during tropical nights was lower than during non-tropical nights. In Daegu, the tropical nights had higher temperatures and cloud covers. Despite these higher temperatures, the ozone concentration during the tropical nights was lower than that on non-tropical nights at most of the air quality stations. This feature was caused by low irradiance, which in turn caused an increased cloud cover. Wind speed was stronger during the tropical nights and dispersed the air pollutants. These meteorological characteristics of the tropical nights reduced ozone concentrations in the Daegu Basin.

Spatial Variability and Long-Term Trend in the Occurrence Frequency of Heatwave and Tropical Night in Korea

최낙빈,이명인 한국기상학회 2019 Asia-Pacific Journal of Atmospheric Sciences Vol.55 No.1

Extreme hot weather in summer is represented by heatwave and tropical night. Based on long-term (1973-2017) surface observations from 73 selected stations, including 60 automated surface observing systems (ASOSs) operated by Korea Meteorological Administration (KMA) and 13 by North Korea, this study examines the spatial variation of the occurrence frequency of heatwave and tropical night in Korea and their long-term trend. The spatial pattern of the heatwave occurrence frequency has different unique features from that of the tropical night. Heatwave develops more frequently in the southern inland regions, while tropical night occurs more in the southern coastal regions and in the urban areas. These hot spots for heatwave and tropical night exhibit a significant positive trend as well. It is also noticeable that the heatwave becomes more frequent in May and September in recent decades. Development mechanisms for heatwave and tropical night are further examined, particularly based on the relationship with cloud fraction. The occurrence frequency of heatwave is correlated negatively with the cloud fraction throughout the warm season, which indicates the daytime temperature is increasing by low cloud fraction. On the other hand, the occurrence frequency of tropical night shows a positive correlation with cloud fraction in May and September, suggesting that the nighttime temperature is effectively increased by enhanced greenhouse effect by cloud for early and late summer. However, the correlation becomes negative in mid-summer (June to August), in which the increased daytime temperature with low cloud fraction tends to affect the nighttime temperature as well. Because of this, the tropical night is more likely accompanied by the heatwave in recent decades.

대구시 열대야 대응 구역 설정을 위한 야간 찬공기 유동성 분석

서보용 ( Bo-yong Seo ),이상범 ( Sang-beom Lee ),권순범 ( Soon-beom Gwon ),차재규 ( Jae-gyu Cha ),정응호 ( Eung-ho Jung ) 한국지리정보학회 2020 한국지리정보학회지 Vol.23 No.3

도시에서의 폭염발생은 기본적으로 지구온난화에 영향을 받으나, 도시에서 발생하는 인공열 배출과 열축적이 큰 토지피복의 영향으로 더욱 가중된다. 특히 도시폭염의 영향은 야간 열대야 발생에도 직접적 영향을 준다. 그러나 기본적으로 주간의 폭염대응에 비해 열대야 대응수단 선택은 매우 제한적이다. 본 연구에서는 대구시를 대상으로 열대야 대응 방안으로 야간 찬공기 유동 특성을 분석하고 이의 공간적 활용가능성을 제시하고자 하였다. 연구방법은 찬공기 유동 분석 프로그램인 KLAM_21을 활용하여 대구시의 찬공기 유동의 공간적 특성인 찬공기 높이 및 유동범위와 유속 및 유동방향을 정량적으로 분석하였다. 분석결과 대구시 주변산지에서의 찬공기 생성, 유동은 매우 활발하나 열대야 발생지역인 도심지역으로 유입이 제한적인 것으로 나타났다. 그러나 일부 시가지에서는 주변산지로부터 유입되는 찬공기 유동성이 매우 활발하여 열대야 대응에 매우 효과적인 공간적 조건을 가지고 있는 것으로 나타났다. 이러한 공간적 조건을 도시계획적 차원에서 활용하면 열대야 대응방안 개발에 매우 유용할 것으로 판단된다. Heat wave generation in cities is basically affected by global warming, but it is further exacerbated by the impact of artificial heat emission and heat accumulation in the city. In particular, the effects of urban heat waves directly affect the occurrence of tropical nights. Basically, however, the choice of countermeasures against tropical nights is very limited compared to the daytime heat wave response. The purpose of this study was to analyze the characteristics of cold air flow at night as a countermeasure against tropical nights in Daegu Metropolitan City and to suggest its spatial applicability. As a research method, the spatial characteristics (flow velocity, flow rate, flow direction and range) of cold air flow in Daegu were quantitatively analyzed using KLAM_21, a cold air flow analysis program. As a result of the analysis, it was found that cold air generation and flow in the surrounding mountains of Daegu Metropolitan City was very active, but the inflow was limited to the urban area, which has tropical nights. However, it has been shown that the flow of cold air flowing from the surrounding mountains is very active in some urban areas, so it has spatial conditions that are very effective in countering tropical nights. If these spatial conditions are used for the urban planning, it will be very useful to develop countermeasures for tropical nights.

Original Article : A Study on the Thermal Characteristics of Midsummer in Daegu Metropolitan Area

( Myung Hee Park ),( Joon Soo Lee ),( Won Shik Ahn ),( Hae Dong Kim ),( Sung Nam Oh ) 한국환경과학회 2013 한국환경과학회지 Vol.22 No.6

This study aims to examine the actual status of the urban heat island in Daegu by analyzing the data of 17 automatic weather stations installed in the Daegu area. And the results can be summarized as follows: First, regarding the temperature distribution in Daegu by summer time zones, for the 31 days(August 1st till 31st), 18 days showed daily maximum temperature over 30℃, and 11 days indicated daily minimum temperature over 25℃. The day that showed the highest daily maximum temperature was August 5th, which indicated 36℃. Second, about the spatial distribution of time ratio exceeding 30℃ and 25℃, the area with the highest time ratio exceeding 30℃ is mostly the downtown(central area), eastern area, and northern area. Meanwhile, regarding the time ratio exceeding 25℃, the downtown area centering around the central area were high as over 70%, and the outskirts were low as under 65%. Third, considering the temporal distribution of daily maximum temperature and daily minimum temperature, daily maximum temperature was shown around 14:00 to 15:00 while the daily minimum temperature was indicated around 17:00 to 18:00. Daily maximum and minimum temperature were appeared at northeast and downtown, respectively. Fourth, regarding the spatial distribution of tropical days and tropical night days, tropical days showed 77%and tropical night days indicated 42% before and after the 24th and also the 13th each. Tropical days were occurred up to 24 days at northeastern area. And the southwestern area of Daegu showed under 22 days. The downtown showed the 14 days of the tropical night. However, the outskirts indicated relatively few days as under 10 days. Fifth, about the spatial distribution of the average daily temperature range (the difference between the highest temperature and lowest temperature), the central area, the central part of the city, showed the smallest as 7.2℃, and as it was closer to the northern area, it became larger, so in the eastern and northern area, it was over 8.8℃or so.

일 최저 기온을 이용한 한국의 폭염사상 추세

김령은,원정은,이정민,최정현,김상단 한국습지학회 2019 한국습지학회지 Vol.21 No.4

Heat waves are a global phenomenon that exacerbate the risks associated with heat exposure and cause fatal human injury. The subject of this study was tropical night, one of the forms of heat waves. In this study, we investigated how the trend of tropical night in Korea is changing. From 1973 to 2018, we analyzed the temporal changes of the six tropical nights using daily minimum air temperature at 60 ASOS stations in Korea Meteorological Administration. From these analyzes, 10 sites were selected as attention sites for tropical nights: Incheon, Gangneung, Cheongju, Jeonju, Gwangju, Jangheung, Yeosu, Geoje, Gumi, Yeongdeok. The severe sites for tropical nights were identified as 14 sites including Hongcheon, Yangpyeong, Suwon, Wonju, Boryeong, Daejeon, Buan, Jeongeup, Mokpo, Geochang, Miryang, Pohang, Jeju, and Seogwipo. At the severe sites identified, special tropical night measures will need to be established. 폭염은 전 세계에서 나타나고 있는 현상으로 열 노출과 관련된 위험을 악화시키고, 치명적인 인명피해를 초래한다. 본 연구에서는 폭염의 한 가지 형태 중 하나인 열대야를 대상으로 한국의 열대야 추세가 어떻게 변화하고 있는 지를 살펴보았다. 1973년부터 2018년까지 한국 기상청 ASOS 60개 지점의 일 최저 기온을 이용하여 여섯 개의 열대야 특성의 시간적인 변화를 분석하였다. 이러한 분석으로부터 열대야 관심지역은 인천, 강릉, 청주, 전주, 광주, 장흥, 여수, 거제, 구미, 영덕 등 10개 지역, 열대야우심지역은 홍천, 양평, 수원, 원주, 보령, 대전, 부안, 정읍, 목포, 거창, 밀양, 포항, 제주, 서귀포 등 14개 지역이 식별되었다. 제안된 열대야 우심지역에는 특별한 열대야 대책이 수립될 필요가 있을 것이다.

주요도시의 폭염 및 열대야 가능성에 관한 정량적 검토

김금지(Kim Keum-Ji),여인애(Yeo In-Ae),윤성환(Yoon Seong Hwan) 한국건축친환경설비학회 2011 한국건축친환경설비학회 학술발표대회 논문집 Vol.2011 No.3

This study analysis the possilities of Extreme Heat and Tropical Night in Seoul, Daegu and Susan in August with Automatic Weather System from 2000 to 2008year, then evaluate thermal comfort. It shows that the range of thermal comfort is different according to district or the occurrence of the Extreme Heat and Tropical Night. In case of Daegu, It shows a more higher level of HI than Seoul and Busan. and In case of Busan, the range of DI also has a [high] level of Discomfort Index under no-extreme heat condition due to a high Relative Humidity in Busan.

하절기 단일건물 주변 외부공간의 장·단파 복사관측과 해석

최동호,백창현,이부용,이인규 한국태양에너지학회 2019 한국태양에너지학회 논문집 Vol.39 No.1

In this study, we analyzed the relationship between four elements: long-wave radiation, the direction of the building, BVR (Building View Ratio), and cloud amount. We examined how long-wave radiations surrounding a building influences the perception of heat in the summer. The results are as follows. ① Long-wave radiation and BVR are highly correlated regardless of geographical direction. ② Especially, during dawn in a clear day, areas with high BVR observed high levels of long-wave radiation. ③ This correlation suggests that higher BVR in urban areas will result in a greater number of tropical nights. 본 연구에서는 장파복사, 건물 방향, BVR (Building View Ratio), 운량 등 네 가지 요소를 분석하였으며,여름철 관측에 의한 장파복사와 건물 옥외의 열환경 관계를 분석하였습니다. 결과는 다음과 같습니다. ① 장파복사와 BVR은 지리적 방향에 관계없이 높은 상관성이 있습니다. ② 특히 맑은 날의 새벽 시간, BVR이 높을수록 많은 장파복사량을 관찰하였다. ③ 이 상관관계는 도시 지역의 BVR이 높을수록 열대야가 많아짐을 시사한다.

연구논문 : 대구와 제주의 폭염 및 열대야의 발생 특성

김진아 ( Jin Ah Kim ),김규랑 ( Kyu Rang Kim ),김백조 ( Baek Jo Kim ) 한국환경과학회 2015 한국환경과학회지 Vol.24 No.11

Observation data (1981-2014) and climate change scenario data (historical: 1981-2005; RCP 2.6 and 8.5: 2006-2100) were used to analyze occurrence and future outlook of the extreme heat days and tropical nights in Daegu and Jeju. Then we compared the mortality and observations data (1993-2013). During 1981-2014, the average of extreme heat days (tropical nights) was 24.41 days (12.47 days) in Daegu, and 6.5 days (22.14 days) in Jeju. Extreme heat days and tropical nights have been similarly increased in Daegu, but tropical nights increased more than extreme heat days in Jeju. Extreme heat days and tropical nights in both, Daegu and Jeju showed high correlation with daily mortality, specifically Daegu’s correlation was higher than that of jeju. The yearly increasing rate of extreme heat of the future (2076-2100) was 1.7-3.6 times and 7.8-37.7 times higher than the past (1981-2005) in Daegu and Jeju, respectively. The yearly increase rate of tropical nights of future was 2.6-5.0 times and 2.9-5.6 times higher in Daegu and Jeju, respectively. During 2006-2100 periods, the trend of extreme heat days was observed both in Daegu and Jeju. On the average, extreme heat days and tropical nights in Jeju increased more than that of Daegu. However, the trend of extreme heat days increase in Daegu was higher than that in Jeju, whereas, the trend of tropical nights in Jeju was higher than that in Daegu.

Analysis of Atmospheric Pattern Associated with the Extreme Hot Event using Self-organizing Map

Hyerin Kim,Myong-In Lee,Joonlee Lee 한국기상학회 2021 한국기상학회 학술대회 논문집 Vol.2021 No.10

Extreme hot events during East Asian summer season can be considered by two cases: heatwave with daytime and tropical night with nighttime. Those two events cause a lot of damages to modern society, such as heat illnesses and insomnia. In general, heatwaves develop in a dry and stable atmospheric condition with shortwave radiation and adiabatic warming. In contrast, tropical nights occur in a wet and warm atmospheric condition during nighttime with longwave radiation and warm advection. According to the previous studies, as the occurrence of heatwaves increases in recent years, tropical night events have increased due to surface heating in the daytime, indicating an increasing number of two events occurring simultaneously. Some studies show atmospheric circulation patterns associated with extreme heat events by statistical method or dynamical method. However, studies are still limited in explaining atmospheric circulation by classifying two extreme events through objective statistical methods. Therefore this study aims to analyze the large-scale atmospheric circulation pattern associated with heatwaves and tropical nights by objectively classifying based on the self-organizing method (SOM). As a result of SOM, the location of the anticyclonic circulation is different with respect to heatwaves and tropical nights, leading to different wind directions around the Korean Peninsula. In particular, pure tropical nights without heatwaves in the daytime show notable discrepancies with atmospheric conditions of tropical nights with heatwaves.