(Abstract)
This study aims to design the Urban Environment Climate Map based on the research of urban climate and atmosphere actual conditions, and to present the atmospheric environment evaluation and the controlling methods by exploring environment...
(Abstract)
This study aims to design the Urban Environment Climate Map based on the research of urban climate and atmosphere actual conditions, and to present the atmospheric environment evaluation and the controlling methods by exploring environment-oriented urban planning based on the research mentioned above.
Characteristics of urban warming phenomenon were studied using degree days for three big cities(Seoul, Busan, Daegu) adjacent to airport. Time variation of the cooling and heating degree days was analyzed using the daily mean air temperature data measured at the six meteorological observatory for long-term periods(25~43years).
The results for the big cities are as followings: It was found that the heating degree days trended to decrease from year to year. The cooling degree days were nearly unchanged during the same analysis periods. The number of days calling for air-heating also tended to decrease as time passes. Those of air-cooling were nearly unchanged during the same time. It suggests that the change of air-heating condition owing to urbanization came in evidence in the winter season, but that of air-cooling condition was slight in the summer season.
On the other hand, the long-term trends of degree days were very small in airport areas except for Kimhae airport. Hence, the gaps of degree days between big cities and rural airport areas are increasing.
It is well known that urban relative humidity has continuous decreasing trend owing to the influence of urbanization. The change of relative humidity is directly influenced by two factors, namely, temperature effect and water vapor effect in various urban effects.
In this study, the temperature and the water vapor effects on the relative humidity change were analyzed by using monthly mean relative humidities for a long period(1961~2005) in Daegu and Chupungnung.
The major results obtained in this study can be summarized as follows. Firstly, the urban dryness was caused mainly by water vapor effect in summer. But, for the other seasons, the urban dryness is mainly due to the temperature effect. Secondly, the relative humidity in Daegu is on the decrease until now. This phenomenon is similar to another Korean huge cities such as Seoul, Daejeon and Incheon. But, it is different compared with Japanese huge cities such as Tokyo, Osaka and Nagoya, indicating a standstill in relative humidity change after 1980s.
In this study, we analyzed the relationship between the time-variation trend of air pollution concentration index and the meteorological conditions with CO(carbon monoxide) concentration and meteorological observation data in high-CO episode days. CO is a representative automobile air pollutant. The results are as follows;
Most of the high-CO episode days within 30 classes appeared in winter season. Most of them appeared under the surface weather conditions with east-west high-pressure system. The surface winds in this high-pressure area were very light. The high-CO episode days were due to unusual accumulation within urban atmosphere in the morning.
In this study, we investigated the difference of air pollutants dispersion phenomenon using U.S EPA ISCLT3 model according to applying the different meteorological data observed at two points for Seongseo industrial complex of Daegu. Two points are the spot site of Seongseo industrial complex and Daegu meteorological observatory.
The winds speed of the spot site were smaller than those of Daegu meteorological observatory. In the winter season, the differences came to about 50% for the period(1 February 2001~31 January 2002). Wind directions were also fairly different at two points. The air pollutants dispersion phenomenon estimated from our numerical experiments were also fairly different owing to the meteorological conditions at two points.
This study, taking advantage of the micro-scale model, conducted a Atmospheric Numerical Simulation considering the building plans in order to interpret the effects on the Heat Island Effect within the complex and spread of air pollutants among the Seongseo industrial complex and a large-scale apartment complex beside the road. As a result of the Numerical Simulation to the existing Dream City, without considering 'wind corridor,' as for the distribution of the wind field, plasma vortex phenomenon was shown at the wall surface of the tall building, re-inflow of wind into the complex by Wake Capture of the wind at the apartment front side, and stagnation of wind by weak wind velocity.
The result of the Numerical Simulation rearranging Dream City considering 'wind corridor' shows that as for the distribution of the wind field, the wind velocity within the complex was more than 3㎧ faster than the other area, and there was smooth flow with stagnation.
On the other hand, the result of the Numerical Simulation of existing Dream City without considering the wind corridor of the city shows that as for the distribution of temperature, the interfering with the flow due to the apartment structures, and the decreased speed of heat diffusion resulting from holding radiant energy within the complex due to the concrete and asphalt caused heat stagnation within the complex even during the night, which resulted in Heat Island Effect.
The result of the Numerical Simulation rearranging Dream City considering 'wind corridor' shows that as for the temperature distribution within the complex, the temperature within the complex fell by more than 0.3℃ due to the active air inflow.
In this study, we made a urban climate map for Daegu metropolitan area. Air pollution, climate, land-use and anthropogenic heat emission data were analyzed. And a regional atmospheric circulation model was run to understand the characteristics of local atmospheric circulation. It is necessary to evaluate quantitatively the wind ventilation land in Daegu. Field observation were also performed to certify the effect of local circulation wind to serve improving urban thermal environment.
As a results, we could classify Daegu region as five categories. The urban climatological characteristics are as follows:
Downtown area is the poorest in air pollution and climatological conditions since the emissions of air pollutants and anthropogenic heat are much but the function to mitigate these phenomenon are small. Hence it is necessary to reduce the emissions to improve atmospheric environment. It is regarded as very useful to take advantage of the concept of urban ventilation lane as one of its policy options to improve atmospheric environment around Mt. Palgong, Mt. Apsan and Suseong-Gu. In the north-western regions, it is required to careful concern in block planning since a clean and cool air and a polluted air are flowing into this area through two rivers-Ion and Kumho. The clean and cool air comes into this area through Ion River which flows from north(rural area) to south. The polluted air comes from downtown through Kumho River which flows from east to west.