• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 1999년도 Proceedings of International Symposium on Remote Sensing
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• pp.231-236
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• 1999

Accurate ocean surface fluxes with high resolution are critical for understanding a mechanism of global climate. However, it is difficult to derive those fluxes by using ocean observation data because the number of ocean observation data is extremely small and the distribution is inhomogeneous. On the other hand. satellite data are characterized by the high density, the high resolution and the homogeneity. Therefore, it can be considered that we obtain accurate ocean surface by using satellite data. Recently we constructed ocean surface data sets mainly using satellite data. The data set is named by Japanese Ocean Flux data sets with Use of Remote sensing Observations (J-OFURO). Here, we introduce J-OFURO. The data set includes shortwave radiation, longwave radiation, latent heat flux, sensible heat flux, and momentum flux etc. Moreover, sea surface dynamic topography data are included in the data set. Radiation data sets covers western Pacific and eastern Indian Ocean because we use a Japanese geostationally satellite (GMS) to estimate radiation fluxes. On the other hand, turbulent heat fluxes are globally estimated. The constructed data sets are used and shows the effectiveness for many scientific studies.

• 대기
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• 제16권2호
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• pp.111-124
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• 2006

This study examines seasonal variability of the surface energy balance at the King Sejong Station, Antarctica, using measurements and estimates of the components related to the balance for the period of 1996 to 2004. Annual average of downward shortwave radiation at the surface is 81 $Wm^{-2}$ which is 37% of the extraterrestrial value, with the monthly maximum of 188 $Wm^{-2}$ in December and the minimum of 8 $Wm^{-2}$ in June. These values are relatively smaller than those at other stations in Antarctica, which can be attributed to higher cloudy weather conditions in Antarctic front zone. Surface albedo varies between ~0.3 in the austral summer season and ~0.6 in the winter season. As a result, the net shortwave radiation ranges from 117 $Wm^{-2}$ down to 3 $Wm^{-2}$ with annual averages of 43 $Wm^{-2}$. Annual average of the downward longwave radiation shows 278 $Wm^{-2}$, ranging from 263 $Wm^{-2}$ in August to 298 $Wm^{-2}$ in January. The downward longwave radiation is verified to be dependent strongly on the air temperature and specific humidity, accounting for 74% and 79% of the total variance in the longwave radiation, respectively. The net longwave radiation varies between 25 $Wm^{-2}$ and 40 $Wm^{-2}$ with the annual averages of 30 $Wm^{-2}$. Accordingly, the annual average energy balance is dominated by radiative warming of a positive net all-wave radiation from September to next March and radiative cooling of a negative net all-wave radiation from April to August. The net all-wave radiative energy gain and loss at the surface is mostly balanced by turbulent flux of sensible and latent heat. The soil heat flux is of negligible importance in the surface energy balance.

• 한국수자원학회논문집
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• 제46권5호
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• pp.465-476
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• 2013

방출장파복사량은 수치예보모형, 수문모형, 증발산 등에 사용되는 인자로 지구의 에너지 균형을 이해하는데 필수적이다. 현재 국내외에서는 이를 정확하게 관측하기가 어려우며, 또한 공간적인 제약이 따른다. 따라서, 본 연구에서는 원격탐사 기술을 적용함으로써 지상관측의 단점을 보완하기 위해 정지궤도 위성인 Communication, Ocean and Meteorological Satellite (COMS)를 사용하여 방출장파복사량(Outgoing Longwave Radiation, $R_{lu}$ )를 계산하였다. 이 자료의 검증을 위해 유량조사사업단에서운영 관리하는 청미천/설마천 Flux Tower의 자료를 사용하여 계산된 $R_{lu}$ 와 MODIS 위성자료를 사용하여 계산된 $R_{lu}$ 를 비교 및 검증하였다. 전반적으로 COMS의 자료가 높은 상관계수를 나타내어 COMS의 사용가능성을 보여주었다. 이러한 결과를 바탕으로 향후 COMS를 이용한 증발산 산정 연구를 할 계획이다.

• 대기
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• 제23권1호
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• pp.39-45
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• 2013

A parameterization for the scattering of longwave radiation by ice clouds has been developed based on spectral scattering property calculations with shapes and sizes of ice crystals. For this parameterization, the size distribution data by Fu (1996) and by Michell and Arnott (1994) are used. The shapes of ice crystal considered in this study are plate, solid column, hollow column, bullet-rosette, droxtal, aggregate, and spheroid. The properties of longwave scattering by ice crystals are presented as a function of the extinction coefficient, single-scattering albedo, and asymmetry factor. The heating rate and flux by the radiative parameterization model are calculated for wide range of ice crystal sizes, shapes, and optical thickness. The results are compared with the calculated results using a six-stream discrete ordinate scattering algorithm and Chou's method. The new method (with various habits and size distributions) provides a good simulation of the scattering properties and cooling rate in optically thin clouds (optical thickness < 5). Depending on the inclusion of scattering by ice clouds, the errors in the calculation of the cooling rates are significantly different.

• 대한원격탐사학회지
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• 제35권1호
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• pp.195-201
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• 2019

The Outgoing Longwave Radiation (OLR) is an important satellite-driven variable for understanding the Earth's energy budget balance. The geostationary OLR retrievals require angular and spectral integration using an empirical equation for irradiance flux-to-OLR from a regression analysis, which determines the accuracy of the narrowband satellite-based OLR. We selected homogeneous pixels which is satisfied less temporal-spatial variability of cloud, on three infrared channels (6.7, 10.8, $12.0{\mu}m$) of the first multipurpose geostationary satellite in Korea, namely the Communication, Ocean and Meteorological Satellite/Meteorological Imager (COMS/MI). Multiple regression analysis was performed to retrieve OLR with improved accuracy using selected parameters based on theoretical and physical significance. This algorithm yielded retrieval with higher accuracy than broadband-based OLR retrieval: RMSE of 10.54 to $3.81W\;m^{-2}$, and bias of -8.49 to $-0.07W\;m^{-2}$.

• 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.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 1992년도 한국우주과학회보 제1권1호
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• pp.12-12
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• 1992

Results from the Earth Radiation Budget Experiment (ERBE) will help interpret the data from the operational satellite system. However, a major problem exists because a follow-on experiment to ERBE is not planned until the late 1990`s. Meanwhile, it will be necessary to provide OLR estimates from the operational satellite system. Since 1973the outgoing long wave radiation(OLR) data have been obtained by the 10#m window radiance(AVHRR) estimation technique from he observation NOAA operational satellites. However, those data have not been universall if accepted because they are estimated from the radiance in but one narrow spectral regiou. However , this type of technique has not been exploited for use with data from the ]fIRS multispectral radiometer. Since the radiance data measured by HIRS contains more: information on atmospheric variables than the AVHRR, it is a potentially better instrument for operational estimates of the OLR In this study, results from model are better flux estimates than the AVHRR, The technique is then tested by comparing simultalleous AVHRR and HIRS OLR estimations with a radiation model flux calculation froml homogeneous atmospheric scenes at the regions of desert and subtropic ocean.

• 한국대기환경학회지
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• 제19권3호
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• pp.285-296
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• 2003

The measurement of the radiation energy, trunk temperature, leaf area index (LAI), air temperature, vapor pres-sure, and precipitation has been conducted under a mixed forest at Kwangneung Arboretum during the period of 2001. Characteristics of the diurnal and seasonal variation of the radiative energy were investigated. The aerodynamic roughness length was determined as about 1.6 m and the mean albedo was about 0.1 The downward short-wave radiation was linearly correlated with the net radiation and its correlation coefficient was about 0.96. From this linear relation, the heating coefficient was calculated and its annual mean value was about 0.21 The albedo and heating coefficient was varied with season, surface characteristics, and meteorological conditions. The diurnal and seasonal variations of radiation energy were discussed in terms of the surface characteristics and meteorological conditions. In the daytime, during clear skies, net radiation was dominated by the shortwave radiation. In presence of clouds and fog, the radiation energy was diminished. At night, the net radiation was entirely dominated due to the net longwave radiation. There was no distinct diurnal variation in net radiation flux during the overcast or rainy days. The net radiation was strongest in spring and weakest in winter. The seasonal development in leaf area was also reflected in a strong seasonal pattern of the radiation energy balance. The timing, duration, and maximum leaf area and trunk temperature were found to be an important control on radiation energy budget. The trunk temperature was either equal or warmer than air temperature during most of the growing season because the canopy could absorb a substantial amount of sunlight. After autumn (after the middle of October), the trunk temperature was consistently cooler than air temperature.

• 대한원격탐사학회지
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• 제6권2호
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• pp.75-88
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• 1990

NOAA 위성의 narrow-band AVHRR(Advanced Very. High Resolution Radiometer) 적 외선 채널과 broad-band 0.2 - 50$\mu\textrm{m}$ 영역의 ERBE(Earth Radiation Budget Experiment) scanning instrument에 의하여 관측된 radiance로부터 추정된 지구의 대기 외장파복사량 (Outgoing Longwave Radiation:OLR) 이 비교조사되었다. 이를 위하여 1985년 4월, 7월, 10월과 1986년 1월에 위성에서 관측된 radiance를 각각 이용하였고 비교된 OLR은 위도와 경도가 각각 2.5$^{\circ}$ 간격으로 구분된 grid내에서 일치(collocate)시켜 지역별(zonal), 그리고 전지구(global)규모 로 비교되었다. ERBE와 AVHRR에 의하여 각각 추정된 OLR값의 차(ERBE minus AVHRR)에 의한 분석 결과는 주간의 경우 -1~2 W/m$^2$의 값과 야간의 경우 4~7 W/m$^2$의 값으로 비교적 좋은 일치를 보였지만 이들의 RMS는 하절(6월)에 12 W/m$^2$와 동절(12월)에 5 W/m$^2$의 값으로 다소 높은 차이를 보였다. 한편, 이들 OLR값을 관측지역에 따라 큰 차 이를 나타내어 사막지역과 아열대고기압(subtropical ocean)대에서는 상반된 결과를 보였다. 이들 지역에 대한 차이는 지역적 기온구조와 지표온도의 영향을 다 고려하지 못하고 OLR 측정치를 도 출하는 대기복사모델(radiation model)의 regional systematic bias에서 기인된 것으로 해석된다. 즉 사막의 지표역전층에 대한 AVHRR과 해면의 대기구조에 대한 ERBE의 OLR은 상반된 영향을 보였다.

• 한국해양학회지
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• 제30권2호
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• pp.91-115
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• 1995

동해에서의 해양-대기 열교환량을 1961년부터 1990년까지의 선상관측자료와 1976 년부터 1985년까지의 일본기상처 부표자료를 이용하여 구하였다. 그리고 이 결과와 해 양상층부 200m 내의 열용량의 계절변화로부터 해양내부의 열유동량을 계산하였다. 겨 울에는 유입되는 단과복사량과 방출되는 장파오복사량의 크기가 비슷해 복사에 의한 열방출량은 적지만 열속과 자멸속이 강하여 전 해역에서 대기로 많은 열량을 방출한 다. 유효열방출량의 공간적인 변화폭은 100 Wm/SUP -2/이상이며, 최대의 열방출량은 쓰가루해협 부근에서 일어나고 대한해협과 울릉분지역등 남부역이 높은 방출량이 나타 난다. 특히 남서 해역의 강한 열방출이 겨울에 동해 중층균실수의 형성에 영향을 주는 것으로 보인다. 여름에는 강한 태양복사와 낮은 난류속의 영향으로 전해역에서 120~ 140 Wm/SUP -2/의 비슷한 크기로 해양이 가열된다. 해양내부의 열유동은 일본연안에서 양의 값을 나타내 여름의 강한 대마난류에 의한 열량의 유입을 보이며, 그 크기는 해 면을 통해 흡수한 열량보다 커서 여름에는 대마난류에 의한 열유입이 중요함을 보여준 다. 한국연안에서는 음의 값으로 수온이 낮은 북한 한류계수의 남하를 나타낸다. 봄과 가을은 3월과 100월에 각각 최소, 최대를 나타낸다. 유효열교환량의 연변화폭은 남서 해역의 경우 약 580 Wm/SUP -2/이다. 해표면을 통한 연평균 유효열교환량은 모든 해역 에서 음의 값으로 대기중으로 열량을 방출하며, 그 크기는 쓰가루해협부근에서 -130 Wm/SUP -2/로 강하고 대한해협과 울릉분지역에서도 이웃하는 해역보다 많은 열량을 방 출한다. 위도 35$^{\circ}$~39$^{\circ}$N 사이에서의 공간적인 연평균값의 크기는 단파복사량, 자멸 속, 장파복사, 열속의 크기로 각각 129, -90, -58, -32Wm/SUP -2/으로 유효열교환량은 -51W/SUP -2이다.