• 한국태양에너지학회:학술대회논문집
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• 2009.11a
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• pp.181-184
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• 2009

This study aimed at framing alternative urban planning scenarios reflecting urban planning factors, performing urban climate simulation and evaluating eco-friend and low energy characteristics of each scenario on the viewpoint of urban temperature and energy savings on the target of the costal city including Haeundae District in Busan The results are as follows. 1)The fact that urban higher temperature is approximately 2.5 times higher in the building constructed area than whole urban area was represented severe higher temperature phenomenon in the built-up area. Ground greening, water scenario and soil scenario could be expected peek air temperature alleviating effect in order. Especially water scenario had significant effect(maximum $2.5^{\circ}C$) on lowering of air temperature.

• Atmosphere
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• v.28 no.4
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• pp.427-441
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• 2018

This study examines the impact of the urban parameterization scheme and the land cover change on simulated near surface temperature using Unified Model (UM) over the Seoul metropolitan area. We perform four simulations by varying the land cover and the urban parameterization scheme, and then compare the model results with 46 AWS observation data from 2 to 9 August 2016. Four simulations were performed with different combination of two urban parameterization schemes and two land cover data. Two schemes are Best scheme and MORUSES (Met Office Reading Urban Surface Exchange Scheme) and two land cover data are IGBP (International Geosphere and Biosphere Programme) and EGIS (Environmental Geographic information service) land cover data. When land use data change from IGBP to EGIS, urban ratio over the study area increased by 15.9%. The results of the study showed that the higher change in urban fraction between IGBP and EGIS, the higher the improvement in temperature performance, and the higher the urban fraction, the higher the effect of improving temperature performance of the urban parameterization scheme. 1.5-m temperature increased rapidly during the early morning due to increase of sensible heat flux in EXP2 compared to CTL. The MORUSES with EGIS (EXP3) provided best agreement with observations and represents a reasonable option for simulating the near surface temperature of urban area.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.5 no.2
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• pp.47-52
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• 2002

In this study, in order to find out relationship of green space distribution and lower air temperature effect, observed air temperature distribution in and out green space in the cloudy. On basis of the result, we are analyzed relationship of air temperature distribution in and out green space, of green space distribution and air temperature of, lower air temperature effect and the urban in between the green space by using regression analysis. According to the result, the higher temperature zone formed around urban, and the lower temperature zone was similar to shape of green space. In case of the green space, higher temperature zone is formed around paved surface and barren ground, lower temperature zone is done forest and water area. To compare air temperature of windward and leeward around green space, the windward formed the lower temperature zone and although the wind direction is not the leeward to the green space, air temperature formed lower temperature zone to the urban in between the green space.

• 한국태양에너지학회:학술대회논문집
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• 2009.11a
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• pp.44-49
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• 2009

In this study, we performed urrban climate simulation how both the factor of environmental land and artificial factors influence on the formation of urban temperature. With deducing quantitative data, this study could get more accurate results of the urban temperature using urban climate simulation system. In the case of natural land cover, it appeared that there are effects on the lowering temperature and the lower temperature rate appeared in the water land cover on the whole. This is considered as temperature in water land was low because of the characteristics of water land having evaporation latent heat was high and convective sensible heat was low. In case of building which has building coverage ratio, 5% with 10 floors and building coverage ratio, 15 % with 6 floors, it appears that the temperature in the water land is $33.6^{\circ}C$. In case of building coverage ratio 5%, temperature dropped when buildings has more than 4 stories. This is regarded as the size of building is bigger, the temperature dropped in relatively because of the fluctuation of the rate of solar heat from the land. At the present time, the urban temperature are higher because of various artificial factors in the city. With these results, this study supposed to be a basies of the future studies for considering both the composition of building coverate ratio and floor plan.

• Journal of Environmental Science International
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• v.33 no.1
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• pp.75-85
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• 2024

An intensive observing period (IOP) of heatwaves in the urban region of Seoul in the summer of 2023 was carried out to understand the changes in air temperature and road temperature induced by environmental conditions. The temperature observed at eight points with different urban environmental conditions was compared with the temperature by the KMA/AWS to analyze the characteristics of change in air temperature by height and the change in road temperature according to environmental conditions and road sprinkler. The comparison of the average temperature observed in different urban environmental conditions with the temperature observed at KMA/AWS showed that the air temperature in asphalt and open space sites was 0.7 to 2.3℃ higher and that the one in bus stops was 0.9 to 2.3℃ higher. In terms of temperature deviations depending on residential type, the temperature in highly populated areas was about 0.1 to 0.8℃ higher than that of apartment complexes. In addition, regardless of the size of a park, the temperature in the park was lower than the temperature in dense housing areas and apartment complexes. In asphalt and residential areas, the road temperature was higher than the temperature at a height of 150 cm, Conversely, road temperature was lower than air temperature in a shaded shelter and large park. In addition, after spraying a surface road, the road temperature immediately dropped by about 3 to 4℃; however, after about 20 minutes, it rose again to the previous road temperature. This change in road temperature appeared only for the temperature of 30 cm height.

• 한국태양에너지학회:학술대회논문집
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• 2009.11a
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• pp.26-31
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• 2009

This study was analysed influence of urban higher temperature in Busan about time series analysis of AWS data. The results are as follows. (1) The temperature of Busan show min $13.2^{\circ}C$ ~max $15.8^{\circ}C$ by 50 years, it is on the rise. (2) The seasonal adjustment series, summer appeared min $17.5^{\circ}C$ ~max $28.9^{\circ}C$ with primitive series similarly. The winter was min $-11.4^{\circ}C$ ~max $17.9^{\circ}C$, the minimum temperature was more lowly than primitive series and maximum temperature was more higher than primitive series. The results, seasonal adjustment series is guessed with influence difference urban structural element beside seasonal factor. (3) Regional analytical result, January appeared with range of min 28% ~max 196% of the seasonal factor and August appeared min 90% ~ max 106%. One of the case which is of 100% or more of the seasonal factor January 12nd~17th, August appears at the 15~17th.

• Atmosphere
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• v.26 no.1
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• pp.141-158
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• 2016

The objective of this study is to examine the impact of urban canopy and the horizontal resolution on simulated meteorological variables such as 10-m wind speed, 2-m temperature and precipitation using WRF model for a local, convective rainfall case. We performed four sensitivity tests by varying the use of urban canopy model (UCM) and the horizontal resolution, then compared the model results with observations of AWS network. The focus of our study is over the Seoul metropolitan area for a convective rainfall that occurred on 16 August 16 2015. The analysis shows that mean diurnal variation of temperature is better simulated by the model runs with UCM before the convective rainfall. However, after rainfall, model shows significant difference in air temperature among sensitivity tests depending on the simulated rainfall amount. The rainfall amount is significantly underestimated in 0.5 km resolution model run compared to 1.5 km resolution, particularly over the urban areas. This is due to earlier occurrence of light rainfall in 0.5 km resolution model. Earlier light rainfall in the afternoon eliminates convective instability significantly, which prevents occurrence of rainfall later in the evening. The use of UCM results in a higher maximum rainfall in the domain, which is due to higher temperature in model runs with urban canopy. Earlier occurrence of rainfall in 0.5 km resolution model is related to rapid growth of PBL. Enhanced mixing and higher temperature result in rapid growth of PBL, which provides more favorable conditions for convection in the 0.5 km resolution run with urban canopy. All sensitivity tests show dry bias, which also contributes to the occurrence of light precipitation throughout the simulation period.

• Atmosphere
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• v.31 no.3
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• pp.295-309
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• 2021

Diurnal variations of air temperature and relative humidity in the Urban Canopy Layer (UCL) of the Seoul metropolitan area are examined using the Weather Research and Forecasting model coupled with the Seoul National University Urban Canopy Model. The canopy layer air temperature is higher than 2-m air temperature and exhibits a more rapid rise and an earlier peak in the daytime. These result from the multiple reflections of shortwave radiation and longwave radiation trapping due to the urban geometry. Because of the absence of vegetation in the UCL and the higher canopy layer air temperature, the canopy layer relative humidity is lower than 2-m relative humidity. Additional simulations with building height changes are conducted to examine the sensitivities of the canopy layer meteorological variables to the urban canyon aspect ratio. As the aspect ratio increases, net sensible heat flux entering the UCL increases (decreases) in the daytime (nighttime). However, the increase in the volume of the UCL reduces the magnitude of change rate of the canopy layer air temperature. As a result, the canopy layer air temperature generally decreases in the daytime and increases in the nighttime as the aspect ratio increases. The changes in the canopy layer relative humidity due to the aspect ratio change are largely determined by the canopy layer air temperature. As the aspect ratio increases, the canopy layer relative humidity is generally increased in the daytime and decreased in the nighttime, contrary to the canopy layer air temperature.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.23 no.5
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• pp.1-14
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• 2020

In order to improve the urban thermal environment, efforts are being made to increase green areas in cities that include park construction, planting, and green roofing. Among these efforts, urban parks play an important role not only in improving the urban thermal environment, but also in terms of ecosystem services (serving as resting places for citizens, providing cleaner air quality, reducing noise, etc.). Therefore, the purpose of this study is to suggest planning and management guidelines for urban parks that are effective in improving the thermal environment, by analyzing the urban surface temperature reduction performance of urban parks. To do this, first, land surface temperature was calculated by using Landsat 8 images. Second, the PCI (Park Cool Island) index was calculated to identify the temperature reduction performance of urban parks. Third, the characteristics of parks (area, shape, vegetation) and the surrounding spatial characteristics (land cover, building-related variables, etc.) were identified. Finally, the relationship between the PCI indices (PCI scale, PCI effect, PCI intensity) and the characteristics of the parks and their surroundings were analyzed. The results revealed that the parks consisting of a larger area, simple shape, and higher tree coverage ratio had increased PCI performance, and were advantageous for improving the urban thermal environment. Meanwhile, PCI performance was found to have decreased in areas with a higher impermeable area ratio and building coverage ratio. The outcomes of this study can be used to identify priority areas for planning and management of urban parks and can also be utilized as planning and management guidelines for improving urban thermal environment.

• Journal of Environmental Science International
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• v.28 no.10
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• pp.831-840
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• 2019

Recently, summer high temperature events caused by climate change and urban heat island phenomenon have become a serious social problem around the world. Urban areas have low albedo and huge heat storage, resulting in higher temperatures and longer lasting characteristics. To effectively consider the urban heat island measures, it is important to quantitatively grasp the impact of urban high temperatures on the society. Until now, the study of urban heat island phenomenon had been carried out focusing only on the effects of urban high temperature on human health (such as heat stroke and sleep disturbance). In this study, we focus on the effect of urban heat island phenomenon on air pollution. In particular, the relationship between high temperature phenomena in urban areas during summer and the concentration of photochemical oxidant is investigated. High concentrations of ozone during summer are confirmed to coincide with a day when the causative substances (NO2,VOCs) are high in urban areas during the early morning hours. Further, it is noted that the night urban heat island intensity is large.. Finally, although the concentration of other air pollutants has been decreasing in the long term, the concentration of photochemical oxidant gradually increases in Daegu.