• 대기
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• 제22권4호
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• pp.429-436
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• 2012

The performances of the Seoul National University Urban Canopy Model (SNUUCM) under different meteorological conditions (clear, cloudy, and rainy conditions) in summertime are compared using observation dataset obtained at an urban site. The daily-averaged net radiation, sensible heat flux, and storage heat flux are largest in clear days and smallest in rainy days, but the daily-averaged latent heat flux is similar among clear, cloudy, and rainy days. That is, the ratio of latent heat flux to net radiation increases in order of clear, cloudy, and rainy conditions. In general, the performance of the SNUUCM is better in clear days than in cloudy or rainy days. However, the performance in simulating sensible heat flux in clear days is as poor as that in rainy days. For all the meteorological conditions, the performance in simulating latent heat flux is worst among the performances in simulating net radiation, sensible heat flux, and latent heat flux. The normalized mean error for latent heat flux is largest in rainy days in which the relative importance of latent heat flux in the surface energy balance becomes greatest among the three conditions. This study suggests that improvements to the parameterization of processes that are related to latent heat flux are particularly needed.

• 수산해양교육연구
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• 제17권2호
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• pp.209-217
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• 2005

The energy balance of the surface layer of the water (the Yellow Sea, the East China Sea and the East Sea) was examined using satellite data. Variations of the net heat flux were similar to those of the latent heat flux which was more intensive than the sensible heat flux. The sensible heat flux was affected the difference between the sea surface temperature and the air temperature and was less important over the Yellow Sea. The maximum of the latent heat flux occurred in autumn when the air is drier and the wind is stronger. The shortwave radiation flux decreased with the latitude and depended on the cloudiness as the longwave radiation flux does. Annual variations of heat fluxes show that the latent heat flux was more intensive over the East China Sea than the East Sea and the Yellow Sea, while the spatial differences of the other heat fluxes were weak.

• 지구물리
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• 제8권3호
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• pp.159-167
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• 2005

Turbulent fluxes of sensible heat and latent heat were analyzed at King Sejong station in the austral summer of 2002 (December) and 2003 (January and February). Monthly mean air temperatures of January and February (2.2oC) were similar to those averaged over 1988 to 2001. Precipitation was less in January and greater in February than those averaged over last 14 years. In December of 2002 and January, there was precipitation primarily when easterly wind blew usually. The frequency of snowfall was equal to or larger than that of rainfall. In the mean while, precipitation primarily in forms of rainfall occurred with westerly wind in February. In addition, while for easterly wind, temperature and humidity was low, temperature and humidity were high in case of westerly wind. Based on flux footprint, measured flux mainly came from within 300 m with maximum of 40 m upwind, indicating the insignificant role of the sea around the study site. Half-hourly downward short wave radiation amounted up to ∼ 1000 Wm-2 and net radiation ranged from -50 to 600 Wm-2. Half-hourly sensible heat flux was positive at daytime with maximum of ∼ 400 Wm-2, except the 27th and 28th in February of 2003 when it was negative all day despite of positive net radiation at short daytime. Latent heat flux was positive with maximum of ∼ 130 Wm-2. Depending on wind direction, the partitioning of net radiation into the sum of sensible heat flux and latent heat flux was larger than 0.8, indicating the strong source of the land surface for the atmospheric heating. The daytime averaged Bowen ratio (=sensible heat flux /latent heat flux) was significantly greater than 1, indicating that sensible heat flux was the main source to heat the atmosphere over the site.

• 수산해양교육연구
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• 제17권3호
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• pp.404-412
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• 2005

The surface energy budget depends on many factors, such as the type of surface, the soil moisture and the vegetation canopy, the geographical location, daily, monthly and seasonal variations, and weather conditions. In the coastal region, the surface is not homogeneous at various scales for instance water, sand, mud, tall grass, and crops. The energy balance over the vegetation canopy was analyzed with the optical energy balance measuring system. The latent heat flux was more intensive than the sensible heat flux. The sensible heat flux was very small in summer due to the canopy effect and higher in spring and autumn. In summer the development of the atmospheric boundary depended on rather the vertical shear of wind than the sensible heat flux.

• 한국환경과학회지
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• 제4권3호
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• pp.197-206
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• 1995

Surface heat balance of the northern sea of Cheju Island for summer in 1993 and 1994 is analyzed using the observation data obtained by Marine Research Institute, Cheju National University. Each flux elements at the sea surface is derived from the marine meteorological reports with application of an aerodynamical bulk method for the turbulent heat fluxes, and empirical formulae for the long-wave radiation heat fluxes. The flux divergence of oceanic heat transport and the rate of heat storage in the ocean are estimated as residual. The features of the surface heat balance are mainly decided by the solar radiation flux and the latent heat flux for 199B. But the Bowen Ratios were large for 1993. This means that the sensible heat fluxes were nearly equal to the latent heat fluxes for 1993. In this period, mean flux divergence of oceanic heat transport is about 130 W/$m^2$.

• Ocean and Polar Research
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• 제27권3호
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• pp.237-250
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• 2005

To investigate the air mass modification related with Yeongdong Heavy snowfall events, we examined sensible and latent heat fluxes on the East Sea, the energy exchange between atmosphere and ocean in this study. Sensible and latent heats were calculated by a bulk aerodynamic method, in which NCEP/NCAR reanalysis data and NOAA/AVHRR weekly SST data with high resolution were used. Among winter precipitation events in the Yeongdong region, 19 heavy precipitation events $(1995{\sim}2001)$ were selected and classified into three types (mountain, cold-coastal, and warm types). Mountain-type precipitation shows highly positive anomalies of sensible and latent heats over the southwestern part of the East Set When separating them into the two components due to variability of wind and temperature/ specific Humidity, it is shown that the wind components are dominant. Cold-coastal-type precipitation also shows strong positive anomalies of sensible and latent heats over the northern part and over the central-northern part of the East Sea, respectively. It is shown that the sensible heat anomalies are caused mostly by the decrease of surface air temperature. So it can be explained that cold-coastal-type precipitation is closely related with the air mass modification due to cold air advection over warm ocean surface. But in warm-type precipitation, negative anomalies are found in the sensible and latent heat distributions. From this result, it may be postulated that warm-type precipitation is affected by the internal process of the atmosphere rather than the atmosphere-ocean interaction.

• 한국지구과학회지
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• 제22권1호
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• pp.40-46
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• 2001

기상청에서 덕적도와 칠발도에 설치한 해양기상 관측부이 자료를 이용하여 해양 및 대기 특성과 해양-대기간의 열교환을 살펴보았다. 각 관측지점에서의 일평균 현열속 및 잠열속은 벌크공기역학법을 적용하여 계산하였다. 표층수온은 기온과 같이 뚜렷한 연주기를 보이지만, 1달 정도 시간지연을 가진다. 해면기압은 7월에 가장 낮았고 겨울에 가장 높았으며, 습도는 5-8월 사이 비교적 높았다. 풍속은 가을과 겨울에 평균 5m/s 이상으로 강한 편이었다. 현열속 분석결과 가을부터 겨울에 걸처 해양의 열손실이 두드러졌으며, 봄과 여름에는 반대로 대기에서 해양으로의 약한 열전달이 이루어져 연중 순현열속은 해양에서 대기로의 열전달을 보여주었다. 잠열속 분석결과 봄에서 여름까지 대기의 열손실이 나타나지만, 그 외 기간에는 해양의 열손실이 월등히 크게 나타났다. 현열속과 잠열속의 크기를 비교해 볼 때,1-2월을 제외하고는 전반적으로 현열속보다 잠열속에 의한 해양의 열손실이 우세함을 알 수 있었다. 관측지점별로 분석한 열속의 크기와 변동폭은 대체적으로 덕적도에서 더 크게 나타났다. 일정 기간을 선정한 사례연구에서, 1998년 5월사례의 경우 현열속과 잠열속 모두 칠발도에서 더 크고, 1996년 11월 사례의 경우에는 덕적도에서 훨씬 크게 나타났다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume II
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• pp.752-755
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• 2006

Evaportranspiration is an important factor in hydrology cycle. Traditionally, it is measured by using basin or empirical formula with meteorology data, while it does not represent the evaportranspiration over a regional area. With the advent of improved remote sensing technology, it becomes a surface parameter of research interest in the field of remote sensing. Airborne and satellite imagery are utilized in this study. The high resolution airborne images include visible, near infrared, and thermal infrared bands and the satellite images are acquired by MODIS. Surface heat fluxes such as latent heat flux and sensible heat flux are estimate by using airborne and satellite images with surface meteorological measurements. We develop a new method to estimate the evaportranspiration over the rice paddy. The surface heat fluxes are initialized with a surface energy balance concept and iterated for convergent solution with atmospheric correct functions associated with aerodynamic resistance of heat transport. Furthermore, we redistribute the total net energy into sensible heat and latent heat fluxes. The result reveals that radiation and evaporation controlled extremes can be properly decided with both airborne and satellite images. The correlation coefficient of latent heat flux and sensible heat flux with corresponding in situ observations are 0.66 and 0.76, respectively. The relative root mean squared errors (RMSEs) for latent heat flux and sensible heat flux are 97.81 $(W/m^2)$ and 124.33 $(W/m^2)$, respectively. It is also shown that the newly developed retrieval scheme performs well when it is tested by using MODIS date.

• 한국환경과학회지
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• 제24권6호
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• pp.721-729
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• 2015

Surface heat balance of the Gangjeong-Goryung Reservoir is analyzed for 12-17 August 2013. Each flux elements at the water surface is derived from the special field observations with application of an aerodynamical bulk method for the turbulent heat fluxes and empirical formulae for the radiation heat fluxes. The rate of heat storage in the reservoir is estimated by using estimated by surface heating rate and the vertical water temperature data. The flux divergence of heat transport is estimated as a residual. The features of the surface heat balance are almost decided by the latent heat flux and the solar radiation flux. On average for 12-17 August 2014 in the Gangjeong- Goryung Reservoir, if one defines the insolation at the water surface as 100 %, 94 % is absorbed in the reservoir; thereafter the reservoir loses about 30~50% by sensible heat, latent heat and net long-wave radiation. The residue of 50~80 % raises the water temperature in the reservoir or transported away by the river flow during the daytime.

• 한국환경과학회지
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• 제11권4호
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• pp.281-288
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• 2002

This study was carried out for reading the change of local meteorological environment according to dam construction of Nakdong-river using numerical model. The study used PSU/NCAR Mesoscale Model version5(MM5) for inquiring effect of formation of artificial lake after dam construction. The colleague simulated temperature mixing ratio, latent heat flux and sensible heat flux in two cause of existing lake and not. Temperature and mixing ratio in southwest of Andong lake increased because of the air that was warm and moist above the lake moved to southwest due to the northeasterly wind. In the case of existing lake around Andong, latent heat flux increased much in the daytime after sunrise. However, sensible heat flux decreased but it didn't change distinctly in southwest of Andong like the other values.