Influence of cloud fraction and snow cover to the variation of surface UV radiation at King Sejong station, Antarctica

Yun Gon Lee, Ja Ho Koo, Jhoon Kim

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

This study investigated how cloud fraction and snow cover affect the variation of surface ultraviolet (UV) radiation by using surface Erythemal UV (EUV) and Near UV (NUV) observed at the King Sejong Station, Antarctica. First the Radiative Amplification Factor (RAF), the relative change of surface EUV according to the total-column ozone amount, is compared for different cloud fractions and solar zenith angles (SZAs). Generally, all cloudy conditions show that the increase of RAF as SZA becomes larger, showing the larger effects of vertical columnar ozone. For given SZA cases, the EUV transmission through mean cloud layer gradually decreases as cloud fraction increases, but sometimes the maximum of surface EUV appears under partly cloudy conditions. The high surface EUV transmittance under broken cloud conditions seems due to the re-radiation of scattered EUV by cloud particles. NUV transmission through mean cloud layer also decreases as cloud amount increases but the sensitivity to the cloud fraction is larger than EUV. Both EUV and NUV radiations at the surface are also enhanced by the snow cover, and their enhancement becomes higher as SZA increases implying the diurnal variation of surface albedo. This effect of snow cover seems large under the overcast sky because of the stronger interaction between snow surface and cloudy sky.

Original languageEnglish
Pages (from-to)99-109
Number of pages11
JournalAtmospheric Research
Volume164-165
DOIs
Publication statusPublished - 2015 Oct 1

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ultraviolet radiation
cloud cover
snow cover
zenith angle
amplification
ozone
station
Antarctica
transmittance
diurnal variation
albedo
snow

All Science Journal Classification (ASJC) codes

  • Atmospheric Science

Cite this

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abstract = "This study investigated how cloud fraction and snow cover affect the variation of surface ultraviolet (UV) radiation by using surface Erythemal UV (EUV) and Near UV (NUV) observed at the King Sejong Station, Antarctica. First the Radiative Amplification Factor (RAF), the relative change of surface EUV according to the total-column ozone amount, is compared for different cloud fractions and solar zenith angles (SZAs). Generally, all cloudy conditions show that the increase of RAF as SZA becomes larger, showing the larger effects of vertical columnar ozone. For given SZA cases, the EUV transmission through mean cloud layer gradually decreases as cloud fraction increases, but sometimes the maximum of surface EUV appears under partly cloudy conditions. The high surface EUV transmittance under broken cloud conditions seems due to the re-radiation of scattered EUV by cloud particles. NUV transmission through mean cloud layer also decreases as cloud amount increases but the sensitivity to the cloud fraction is larger than EUV. Both EUV and NUV radiations at the surface are also enhanced by the snow cover, and their enhancement becomes higher as SZA increases implying the diurnal variation of surface albedo. This effect of snow cover seems large under the overcast sky because of the stronger interaction between snow surface and cloudy sky.",
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Influence of cloud fraction and snow cover to the variation of surface UV radiation at King Sejong station, Antarctica. / Lee, Yun Gon; Koo, Ja Ho; Kim, Jhoon.

In: Atmospheric Research, Vol. 164-165, 01.10.2015, p. 99-109.

Research output: Contribution to journalArticle

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