A003-0007
Preliminary results of UV index and other biological indices in Asia for the Geostationary Environmental Monitoring Spectrometer (GEMS)

Monday, 7 December 2020
Poster
Hana Lee1, Jhoon Kim2, Ukkyo Jeong3, Won-Jin Lee4, Jongmin Yoon4 and Dongwon Lee4, (1)Yonsei University, Seoul, Korea, Republic of (South), (2)Yonsei University, Department of Atmospheric Sciences, Seoul, Korea, Republic of (South), (3)University of Maryland College Park, College Park, MD, United States, (4)National Institute of Environmental Research, Environmental Satellite Center, Incheon, South Korea
Abstract:
Solar ultraviolet (UV) radiation has a broad range of effects concerning life on Earth, which influences human health and ecosystems in various ways. UV index (UVI) is one of a simple parameter to show the strength of surface UV irradiance. Therefore, UVI has been widely utilized for surface UV monitoring using ground-based and satellite instruments.

Geostationary Environment Monitoring Spectrometer (GEMS) instrument onboard the GEO-KOMPSAT-2 satellite was launched in February 2020. GEMS measures the UV-visible radiance spectrum from 300 nm to 500 nm at a resolution of 0.6 nm over Asia (5°S to 45°N, 75°E to 145°E) and with a high temporal resolution of 1 hour. GEMS UVI product includes four variables to different health and plant effects in East Asia within the GEMS field of regard, namely: (i) UV index, (ii) DNA damage index, (iii) plant response index, and (iv) vitamin D synthesis index.

The UVI algorithm is based on look-up tables using cloud optical depth estimated from the reflectance at 354 nm, total ozone column and surface albedo from the GEMS Level 2 (L2) product. The attenuation caused by absorbing aerosols and clouds is corrected in a post-processing step. GEMS UVI products help analyze the spatial distribution and diurnal variability of surface UV radiation in Asia.

The results of the GEMS UVI were compared with the Brewer spectrophotometer at Seoul, where both GEMS and OMI UVI show overestimation when using monthly climatological absorbing aerosol optical depth (AOD) data. In urban and high polluted areas, the algorithm requires an additional method to correct for absorbing AOD. In the operational GEMS UVI product, we will use the absorbing AOD at 310 nm from the GEMS L2 AOD product.

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