Properties of Solar Radiation Components Reflected by the Sea Surface: - A Case of Jeju Island, South Korea -
Title & Authors
Properties of Solar Radiation Components Reflected by the Sea Surface: - A Case of Jeju Island, South Korea -
Fumichika, Uno; Hayashi, Yousay; Hwang, Soo-Jin; Kim, Hae-Dong;

Abstract
Solar radiation components reflected by the sea surface ($\small{R_{ss}\uparrow}$) are additional energy sources comprising the solar radiation regime. Previous studies, based on observational approaches, indicated that $\small{R_{ss}\uparrow}$ is an available climatological resource. However, an estimation process for $\small{R_{ss}\uparrow}$ has not been established. In this case study over Jeju Island in South Korea, we applied a new estimation process to solar radiation modeling and discussed the spatial distribution of $\small{R_{ss}\uparrow}$ and its seasonal variation. Our results showed that the illuminated area and the intensity of $\small{R_{ss}\uparrow}$ became greatest at the winter solstice and least at the summer solstice. We estimated the illuminated area of $\small{R_{ss}\uparrow}$ as it expanded over the southern slope of Jeju Island. At the winter solstice, on a daily basis, the area and intensity of illumination by $\small{R_{ss}\uparrow}$ were $\small{182.3km^2}$ and $\small{0.41\;MJ\;m^{-2}\;day\;{-1}}$, respectively. Comparing the daily accumulative and instantaneous values of $\small{R_{ss}\uparrow}$ intensity, the difference was about 20 times greater in daily cases than in instantaneous cases. On the other hand, for instantaneous values, the $\small{R_{ss}\uparrow}$ intensity accounted for up to 33% of the three components, i.e., direct, diffuse and reflected radiation in winter solstice. In addition, it was estimated that the sea surface reflectance depended on the wind speed. Therefore, in a practical use of this revised model, wind conditions should be considered as a critical factor in estimating $\small{R_{ss}\uparrow}$.
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