UV Sensitivity to Changes in Ozone, Aerosols, and Clouds in Seoul, South Korea

Woogyung Kim,Jhoon Kim,Hi-Ku Cho,Sang Seo Park

doi:10.1175/jamc-d-13-052.1

Woogyung Kim, Jhoon Kim + Show 2 more

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https://doi.org/10.1175/jamc-d-13-052.1

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Abstract

AbstractThe total ozone (O3) and aerosol optical depth (AOD) at 320 nm have been observed from the ultraviolet (UV) measurements made at Yonsei University in Seoul, South Korea, with Dobson and Brewer spectrophotometers, respectively, during 2004–10. The daily datasets are analyzed to show the sensitivities of UV radiation to changes in O3, AOD, and cloud cover (CC) together with global solar radiation (GS), including the long-term characteristics of surface UV irradiance in Seoul. The UV sensitivities show that 1% increases of O3 and AOD relative to their reference values under all- and clear-sky conditions similarly manifest as 1–1.2% and 0.2% decreases of both daily erythemal UV (EUV) and total UV (TUV) irradiance at the ground level except for TUV sensitivity to O3 (~0.3%). Those UV sensitivities to CC and GS changes are associated with a 0.12% decrease and 0.7% increase, respectively, in fractional UV changes. The trends show that the positive trends of O3 (+7.2% decade−1), AOD (+22.4% decade−1), and CC (+52.4% decade−1) induce negative trends in EUV (−8.4% decade−1) and TUV (−2.5% decade−1), in both UV (−4.7% decade−1), and in EUV (−6.3% decade−1) and TUV (−6.8% decade−1), respectively. On the basis of the multiple linear regression analyses, it is found that UV sensitivity to O3 is relatively high in the forcing factors, but the contributions of the UV forcing factors to the daily variability and the range of UV disturbances due to the variability of the forcing factors are affected more by AOD than by O3 and CC in both UV fractional changes.

Highlights

It is well known that the UV radiation reaching the earth’s surface is damaging to the human body and the ecosystem, and that the ozone layer in the lower stratosphere absorbs a substantial fraction of the harmful UV-B radiation (280–320 nm) from the sun
The inverse effects of surface UV irradiance on ozone, aerosols, and clouds in short-term and long-term changes are demonstrated by measurements and the theory for their absorption and scattering processes (e.g., Herman 2010; Kyle 1991; Liou 1992; Madronich 1993; Madronich et al 1998; McKenzie et al 1991)
Spectral measurements of solar ultraviolet (UV) radiations by Brewer spectrophotometer were used in conjunction with total ozone measurements by Dobson spectrophotometer in Seoul during 2004–10 to investigate the relative influences and trends of the UV forcing factors of O3, aerosol optical depth (AOD) and cloud cover (CC), and global solar radiation (GS), together with their climatological features

Summary

Introduction

It is well known that the UV radiation reaching the earth’s surface is damaging to the human body and the ecosystem, and that the ozone layer in the lower stratosphere absorbs a substantial fraction of the harmful UV-B radiation (280–320 nm) from the sun. On the way through the atmosphere, solar radiation is absorbed and scattered by molecules, aerosols, and clouds. In the UV-B range, ozone is the most effective molecule for absorption. Many studies have investigated the effect of ozone on surface UV radiation (Cho et al 1998; Madronich 1992; McKenzie et al 1991; Stolarski et al 1992), but relatively few studies have considered the effects of aerosols and clouds.

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