• 한국환경과학회지
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• 제23권11호
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• pp.1807-1820
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• 2014

The spatial and temporal changes of the annual mean urban heat island(UHI) intensity were investigated using near surface temperature data measured at 16 automatic weather systems(AWS) in Busan metropolitan area(BMA) during the 11-yr period, from 2000 to 2010. For nighttime, the annual mean UHI intensity at Dongnae(U1) in 2000 was weaker than it in 2010. However the change of the annual mean UHI intensity at Daeyeon(U2) during 11 years was different from it at U1. The annual frequency of the UHI intensity over $5^{\circ}C$ considerably increased at U2 and decreased at U1 during 11 years. The center of the UHI also spatially shifted southward with Daeyeon and Haeundae in BMA. It would be caused by the increase of urban area, population-density and transportation near U2 and by the decrease of them near U1. We found that the spatial and temporal differences of the UHI intensity have coincided with changes of land-use, population density and transportation in BMA.

• 환경영향평가
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• 제21권5호
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• pp.665-681
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• 2012

This study investigates the influence of anthropogenic heat (AH) release on urban boundary layer in the Gyeong-In region using the Weather Research and Forecasting model that includes the Seoul National University Urban Canopy Model (SNUUCM). The gridded AH emission data, which is estimated in the Gyeong-In region in 2002 based on the energy consumption statistics data, are implemented into the SNUUCM. The simulated air temperature and wind speed show good agreement with the observed ones particularly in terms of phase for 11 urban sites, but they are overestimated in the nighttime. It is found that the influence of AH release on air temperature is larger in the nighttime than in the daytime even though the AH intensity is larger in the daytime. As compared with the results with AH release and without AH release, the contribution of AH release on urban heat island intensity is large in the nighttime and in the morning. As the AH intensity increases, the water vapor mixing ratio decreases in the daytime but increases in the nighttime. The atmospheric boundary layer height increases greatly in the morning (0800 - 1100 LST) and midnight (0000 LST). These results indicate that AH release can have an impact on weather and air quality in urban areas.

• 한국대기환경학회지
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• 제28권2호
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• pp.119-130
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• 2012

Heat island phenomena in Chuncheon (Korea) were investigated using air temperature measured by automatic weather stations and temperature dataloggers located at rural and urban sites. Numerical simulation of the phenomena was performed using Weather Research and Forecasting Urban Canopy Model (WRF-UCM) and results were compared with the observation. The model was initialized with NCEP/FNL data. The horizontal resolution of the fine domain is 0.33 km. The results of observational analyses show that the intensity of heat island was significantly higher during the nighttime than during the daytime. The highest measured temperature difference between rural and urban site is $3.49^{\circ}C$ and average temperature difference varies between 1.4 and $1.9^{\circ}C$. Good agreement was found between the simulated and observed temperatures. However, significantly overestimated wind speed was found at the urban sites. The linear regression analysis between observed and simulated temperature shows high correlation coefficient 0.96 for urban and 0.94 for rural sites while for wind speed, a very low correlation coefficient was found, 0.30 and 0.55 respectively.

• 한국대기환경학회지
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• 제9권4호
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• pp.303-309
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• 1993

An observational study of urban heat island was carried out using field data obatined during 6 days in May and August 1992 in Chunchon(population size 180.000). Air temperature was measured at 64 points along two sampling ruoutes by themisters attached to cars. Both routes cover urban and rural area and across the cneter of urban area. Continuous observation of air sonde was perfomed to clarify heights of nocturnal boundary layer(NBL) at the center of urban area. Surface meteorological observations were performed at both urban and rural sites. This study showed that heat island phenomena was obviously observed at the urbanized area during the night time with low wind speed. The average NBL heights exteded to about 10 meters, but varied with meteorological conditions. After sunset, the air temperature decreased with time at both sites and cooling rate at the urban site was greater than the rural site. The maximum heat island intensity was 7.5$^{\circ}$C at 21 LST, May 4. Usingthe two meteorological data sets obtained from urban and rural sites, the air pollutant concentration was calculated by Gaussian plume model which can obtain not only horizontal distribution of concentration but also vertical distribution. The result indicated that the concentration resulted from urban meteorological data set was lower than that from rural meteorological data set. It was also calculated that the air pollutant extended to higher level in urban meteorological data set than that in rural meteorological data set.

• 한국수산과학회지
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• 제27권3호
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• pp.314-325
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• 1994

Characteristics of climate in the eastern coastal regions of Korean Peninsula were studied using the meteorological and coastal sea surface temperature (SST) data which were compiled from 1961 to 1990. In the winter half year (from October to March), air temperature (AT) and precipitation of the eastern coastal regions were considerably higher than those of the western and inland regions, but relative humidity was $8{\sim}15\%$ lower. AT of coastal regions was closely related to the variation of coastal SST. These characteristics were more noticeable in the eastern coastal areas and in lower latitude regions. Quantitatively, the $1.0^{\circ}C$ variation of coastal SST may have resulted in the $1.0^{\circ}C{\sim}1.5^{\circ}C$ variation for AT in coastal regions. In the same way as temperature, vapor pressure in coastal regions was also influenced by coastal SST. Relative humidity change corresponding to the $1.0^{\circ}C$ variation of coastal SST was $3.7\%{\sim}6.5\%$. Net heat exchange amounts were positive (sea surface gaining energy) in all coastal regions. Sea surface gained net heat from March to September, and lost it from October to February. Variation of AT in coastal regions was also related to the sensible and latent heat exchanges. Sensible and latent heat amount corresponding to the $1.0^{\circ}C$ variation of AT were $10Wm^{-2}$ at Kangnung, and $8Wm^{-2}$ at Pohang and $13Wm^{-2}$ at Pusan.

• 한국지구과학회지
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• 제25권7호
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• pp.629-636
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• 2004

구름이 유입하는 경우 해양대기경계층의 발달을 분석하기 위하여, 울릉도에서 관측한 레윈존데 자료와 AWS 자료, 위성사진, 동해에 설치된 부이 자료를 이용하였다. 이 자료를 이용하여 열의 이류와 표층 열속, 구름 유입에 따른 복사에너지를 추정하였다. 혼합층 내의 열 변화 및 혼합층의 발달을 표층 열속과 구름에 의한 장파복사속으로 설명하였다. 열속의 변화를 알아보기 위해 벌크법을 이용하였다. 울릉도, 동해상의 부이, 포항에서 관측한 자료를 이용한 열수지 방정식으로 대기경계층의 열보존 관계를 분석하였다. 구름의 유입으로 인해 일몰 후 지면의 복사냉각이 방해되고, 구름에서 장파복사가 방출된다. 그로 인해 야간에 오히려 기온이 증가하였다. 또 남서쪽으로부터 따뜻한 공기가 이류되어, 하층 대기의 온도를 증가시켰다. 이러한 이유로 혼합층이 파괴되지 않고, 잔류층을 형성하며 남아있었다.

• 한국환경과학회지
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• 제28권7호
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• pp.617-627
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• 2019

This study investigated the relationship between heat-related illnesses obtained from healthcare big data and daily maximum temperature observed in seven metropolitan cities in summer during 2013~2015. We found a statistically significant positive correlation (r = 0.4~0.6) between daily maximum temperature and number of the heat-related patients from Pearson's correlation analyses. A time lag effect was not observed. Relative Risk (RR) analysis using the Generalized Additive Model (GAM) showed that the RR of heat-related illness increased with increasing threshold temperature (maximum RR = 1.21). A comparison of the RRs of the seven cities, showed that the values were significantly different by geographical location of the city and had different variations for different threshold temperatures. The RRs for elderly people were clearly higher than those for the all-age group. Especially, a maximum value of 1.83 was calculated at the threshold temperature of $35^{\circ}C$ in Seoul. In addition, relatively higher RRs were found for inland cities (Seoul, Gwangju, Daegu, and Daejeon), which had a high frequency of heat waves. These results demonstrate the significant risk of heat-related illness associated with increasing daily maximum temperature and the difference in adaptation ability to heat wave for each city, which could help improve the heat wave advisory and warning system.

• 한국농림기상학회지
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• 제5권2호
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• pp.138-149
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• 2003

KoFlux는 생태계와 대기 사이에 교환되는 이산화탄소, 수증기 및 에너지에 대한 우리의 이해를 높이고, FLUXNET과 CEOP등의 지역, 대륙 및 전구 규모의 관측망에 기여하기 위해서 시작되었다. 그거나 한반도의 지형적 특성 때문에 KoFlux의 대부분의 플럭스 타워는 관측에 이상적이지 못한 장소에 위치하고 있다. 탄소 및 에너지 교환의 정량화를 위해서 뿐만 아니라 군락 규모에서 지역 규모로 확장하기 위해서는 관측과 모델링을 병용한 다양한 접근 방법의 적용이 필요하다. 본 연구에서는 지역 규모의 현열 플럭스를 추정하기 위해 타워 플럭스 관측, 대류 경계층(CBL) 수지 방법, MM5 중규모 모형, 그리고 NCAR/NCEP 재분석 자료의 네 가지의 방법을 사용하여 다양한 면적을 대표하는 현열 플럭스를 산출하여 비교하였다. 비록 제한된 짧은 기간의 자료를 사용하였으나, 예비 분석을 통하여 (1) 해남 농경지 플럭스 타워에서 관측된 현열 플럭스가 지표의 불균질성을 보였고, (2) CBL 수지 방법으로 얻어진 지역 규모의 현열 플럭스는 수평 이류 효과의 계산 방법에 따라 다른 결과를 보였으며, (3) MM5 중규모 모형은 타워 플럭스 관측 값과 아주 유사한 현열 값을 수치 모사하였다. 그러나 관측지의 불균질성과 두 방법이 대표하는 면적의 근본적인 차이를 고려할 때, 플럭스 발자국 분석, 지리정보 시스템 및 관측지의 위성 영상 분석에 근거한 타워 플럭스의 공간 대표성을 정량화하는 것이 시급한 것으로 나타났다.

• Nuclear Engineering and Technology
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• 제34권2호
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• pp.165-175
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• 2002

Effects of gap sizes (3.9-44.3 mm) of vertical annuli on nucleate pool boiling heat transfer of water at atmospheric pressure have been obtained experimentally. Through the study, tubes of the closed bottom have been investigated and results are compared with those of a single unconfined tube. According to the results, the annular condition gives much increase in heat transfer coefficient at moderate heat fluxes. The increase is much enhanced 3s the gap size decreases. At the same tube wall superheat (about 3.1 K) the heat transfer coefficient for the least gap size (i.e., 3.9 mm) is more than three times greater than that of the unconfined tube. However, deterioration of heat transfer occurs at high heat flux for confined boiling.

• 대기
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• 제23권1호
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• pp.13-21
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• 2013

In this study, the effects of atmospheric stability and surface temperature on the microscale local airflow are investigated in a hydrological suburban area using a computational fluid dynamics (CFD) model. The model domain includes the river and industrial complex for analyzing the effect of water system and topography on local airflow. The surface boundary condition is constructed using a geographic information system (GIS) data in order to more accurately build topography and buildings. In the control experiment, it is shown that the topography and buildings mainly determine the microscale airflow (wind speed and wind direction). The sensitivity experiments of atmospheric stability (neutral, stable, and unstable conditions) represent the slight changes in wind speed with the increase in vertical temperature gradient. The differential heating of ground and water surfaces influences on the local meteorological factors such as air temperature, heat flow, and airflow. These results consequentially suggest that the meteorological impact assessment is accompanied by the changes of background land and atmospheric conditions. It is also demonstrated that the numerical experiments with very high spatial resolution can be useful for understanding microscale local meteorology.