• Korean Journal of Agricultural and Forest Meteorology
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• v.23 no.4
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• pp.283-294
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• 2021

Solar radiation is an important meteorological factor in the agricultural sector. The ground exposed to sunlight is highly influenced by the surrounding terrains especially in South Korea where the topology is complex. The solar radiation on an inclined surface is estimated using a solar irradiance correction factor for the slope of the terrain along with the solar radiation on a horizontal surface. However, such an estimation method assumes that there is no barrier in surroundings, which blocks sunlight from the sky. This would result in errors in estimation of solar radiation because the effect of shading caused by the surrounding terrain has not been taken into account sufficiently. In this study, the shading effect was simulated to obtain the brightness value (BV), which was used as a correction factor. The shaded relief images, which were generated using a 30m-resolution digital elevation model (DEM), were used to derive the BVs. These images were also prepared using the position of the sun and the relief of the terrain as inputs. The gridded data where the variation of direct solar radiation was quantified as brightness were obtained. The value of cells in the gridded data ranged from 0 (the darkest value) to 255 (the brightest value). The BV analysis was performed using meteorological observation data at 22 stations installed in study area. The observed insolation was compared with the BV of each point under clear and cloudless condition. It was found that brightness values were significantly correlated with the solar radiation, which confirmed that shading due to terrain could explain the variation in direct solar radiation. Further studies are needed to accurately estimate detailed solar radiation using shaded relief images and brightness values.

• Korean Journal of Agricultural and Forest Meteorology
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• v.13 no.1
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• pp.41-46
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• 2011

Reliable information on the surface solar radiation is indispensable for rebuilding food production system in the famine plagued North Korea. However, transfer of the related modeling technology of South Korea is not possible simply because raw data such as solar radiation or sunshine duration are not available. The objective of this study is restoring solar radiation data at 27 synoptic stations in North Korea by using satellite remote sensing data. We derived relationships between MODIS radiation estimates and the observed solar radiation at 18 locations in South Korea. The relationships were used to adjust the MODIS based radiation data and to restore solar radiation data at those pixels corresponding to the 27 North Korean synoptic stations. Inverse distance weighted averaging of the restored solar radiation data resulted in gridded surfaces of monthly solar radiation for 4 decadal periods (1983-1990, 1991-2000 and 2001-2010), respectively. For a direct application of these products, we produced solar irradiance estimates for each sub-grid cell with a 30 m spacing based on a sun-slope geometry. These products are expected to assist planning of the North Korean agriculture and, if combined with the already prepared South Korean data, can be used for climate change impact assessment across the whole Peninsula.

• Korean Journal of Agricultural and Forest Meteorology
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• v.17 no.4
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• pp.281-289
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• 2015

Information on sunshine duration and solar radiation are indispensable to the understanding of crop growth and development. Yet, relevant variables are not available in the Korea Meteorological Administration's (KMA) digital forecast. We proposed the methods of estimating sunshine duration and solar radiation based on the 'sky condition' of digital forecast products and validated using the observed data. The sky condition values (1 for clear, 2 for partly cloudy, 3 for cloudy, and 4 for overcast) were collected from 22 weather stations at 3-hourly intervals from August 2013 to July 2015. According to the observed relationship, these data were converted to the corresponding amount of clouds on the 0 to 10 scale (0 for clear, 4 for partly cloudy, 7 for cloudy, and 10 for overcast). An equation for the cloud amount-sunshine duration conversion was derived from the 3-year observation data at three weather stations with the highest clear day sunshine ratio (i.e., Daegwallyeong, Bukgangneung, and Busan). Then, the estimated sunshine hour data were used to run the Angstrom-Prescott model which was parameterized with the long-term KMA observations, resulting in daily solar radiation for the three weather stations. Comparison of the estimated sunshine duration and solar radiation with the observed at those three stations showed that the root mean square error ranged from 1.5 to 1.7 hours for sunshine duration and from 2.5 to $3.0MJ\;m^{-2}\;day^{-1}$ for solar radiation, respectively.

• 한국태양에너지학회:학술대회논문집
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• 2008.11a
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• pp.208-213
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• 2008

Since The measured solar radiation incident on tilted surfaces by all directions has been widely used as important solar radiation data in installing solar flat-plate collectors. To maximize the incident beam radiation, the slope, which is the angle between the plane of the surface in question and the horizontal, and the solar azimuth angles are needed for these solar thermal systems. This is because the performance of the solar thermal system is much affected by angle and direction of incident rays. Recognizing those factors mentioned above are of importance, actual experiment has been performed in this research to obtain the angle of inclination with which the maximum incident rays can be absorbed. The results obtained in this research could be used in installing optimal solar flat-plate collectors.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 2000.10b
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• pp.94-97
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• 2000

온실의 환경설계 중에서 가장 기본이 되는 냉ㆍ난방 설비용량의 결정을 위하여는 설계외기온(냉ㆍ난방설계), 외기의 습구온도 및 수평면 일사량(냉방설계)과 같은 기상자료가 필요하다. 시설재배에 있어서 환경설비의 용량 부족은 혹한기 또는 혹서기에 작물의 생육에 치명적인 영향을 미칠 수 있다. 또한 설비용량의 과대설계는 설치비 면에서 비경제적일 뿐만 아니라 에너지의 효율적 이용 측면에서도 불리하므로 적정 설비용량의 결정은 매우 중요하고, 따라서 설계용 기상자료의 선택은 매우 신중을 기하여야 한다. (중략)

• 한국태양에너지학회:학술대회논문집
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• 2008.04a
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• pp.142-147
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• 2008

Limited fossil fuels and unstable energy supply are considered as one of the critical problems in architecture requiring large amounts of energy. In order to this challenge, environment-friendly architecture design is required. Especially, Application of solar energy as a clean energy source and one kind of renewable energy. Many sites however are mainly concentrated in the developed countries, and are scarcer within the developing world. Simple radiation estimation models using meteorologically observed input parameters are often used in the applications requiring rough estimations of solar radiation. In this paper, measurements of global solar radiation and cloud data hours in climatological locations in South Korea are used to develop an estimation in solar radiation. The results of measured data are compared with the results obtained from equations, internationally accepted correlations.

• Journal of the Korean earth science society
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• v.40 no.2
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• pp.119-134
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• 2019

In order to analyze the observational environment of solar radiation stations operated by the Korea Meteorological Administration (KMA), we used the digital elevation model (DEM) and the solar radiation model to calculate a topographical shading, sky view factor (SVF) and solar radiation by surrounding terrain. The sky line and SVF were calculated using high resolution DEM around 25 km of the solar stations. We analyzed the topographic effect by analyzing overlapped solar map with sky line. Particularly, Incheon station has low SVF whereas Cheongsong and Chupungryong station have high SVF. In order to validation the contribution of topographic effect, the solar radiation calculated using GWNU solar radiation model according to the sky line and SVF under the same meteorological conditions. As a result, direct, diffuse and global solar radiation were decreased by 12.0, 5.6, and 4.7% compared to plane surface on Cheongsong station. The 6 stations were decreased amount of mean daily solar radiation to the annual solar radiation. Among 42 stations, eight stations were analyzed as the urgent transfer stations or moving equipment quickly and more than half of stations (24) were required to review the observational environment. Since the DEM data do not include artifacts and vegetation around the station, the stations need a detail survey of observational environment.

• Journal of the Korean Solar Energy Society
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• v.39 no.3
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• pp.81-89
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• 2019

Long-term solar irradiance data are required for reliable performance evaluation and feasibility analysis of solar photovoltaic systems. However, measurement data of the global horizontal irradiance (GHI) are only available for major cities in Korea. Neither the direct normal irradiance (DNI) nor the diffuse horizontal irradiance (DHI) are available, which are also needed to calculate the irradiance on the tilted surface of PV array. It is a simple approach to take advantage of the decomposition model that extracts DNI and DHI from GHI. In this study, we investigate variations of solar PV power estimation due to the choice of decomposition model. The GHI data from Korea Meteorological Administration (KMA) were used and different sets of typical meteorological year (TMY) data using some well-known decomposition models were generated. Then, power outputs with the different TMY data were calculated, and a variation of 3.7% was estimated due to the choice of decomposition model.

• Journal of the Korean Solar Energy Society
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• v.32 no.3
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• pp.77-87
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• 2012

Images taken by geostationary satellite may be used to estimate solar irradiance fluxes at earth's surface. It is based on the empirical correlation between a satellite derived cloud index and the irradiance at the ground. For the validation, estimated direct normal Insolation is compared with observed direct normal Insolation at 16 sites over the Korean peninsular from January 1982 to December 2010. Estimated direct normal Insolation shows reliable results with average deviation of -5.4 to +5.9% from the measured values and the yearly averaged direct normal Insolation of Korean peninsula was turned out to be 2.93 $kW/m^2/day$.

• Solar Energy
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• v.16 no.2
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• pp.49-63
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• 1996

Site elavation is one of the major factors which is influencing the incoming insolation. Because nonpermanent gases like ozone, water vapor are unmixed components of the atmosphere and their concentrations are function of height, the site elevation effects the relative proportion of the atmospheric constituents. We have measured solar radiation on Sobaek(1,350m) and in Poonggi area(280m). These values were compared to investigate the their charateristics and the potential for the solar utilization as an alternative energy for both high altitude area and low altitude area. From the results, we conclude that 1) Yearly mean 4,093 $kcal/m^2$. day of the horizontal global radiation in Mt. Sobaek was evaluated for clear day. 2) Insolation on Mt. Sobaek is $6{\sim}7%$ higher than Poonggi area during summer and winter seasons. 3) A significant difference of atomospheric clearness index is observed between Mt. Sobaek and Poonggi area at the same latitude.