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© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Submitted as: research article 21 Oct 2019

Submitted as: research article | 21 Oct 2019

Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Atmospheric Chemistry and Physics (ACP).

Global Distribution and 14-Year Changes in Erythemal Irradiance, UV Atmospheric Transmission, and Total Column Ozone 2005–2018 Estimated from OMI and EPIC Observations

Jay Herman1, Alexander Cede2, Liang Huang3, Jerald Ziemke5, Matthew Kowalewski2, and Karin Blank4 Jay Herman et al.
  • 1University of Maryland Baltimore County JCET, Baltimore, Maryland, USA
  • 2SciGlob Instruments and Services, Ellicott City, Maryland, USA
  • 3Science Systems and Applications, Lanham, Maryland, USA
  • 4NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
  • 5Morgan State University, GESTAR, Baltimore, Maryland, USA

Abstract. Satellite data from the Ozone Measuring Instrument (OMI) and Earth Polychromatic Imaging Camera (EPIC) for ozone amount and scene reflectivity (mostly from clouds) are used to study changes and global distribution of UV erythemal irradiance in mW/m2 E(ζ,ϕ,z,t) and UV index (E/25 mWm2) over the Earth's surface as a function of latitude ζ, longitude ϕ, altitude z, and time t. OMI time series data starting in January 2005 to December 2018 are used to estimate 14-year changes in total column ozone TCO3 and scene reflectivity at 105 specific land plus 77 ocean locations in the Northern and Southern Hemispheres. Estimates of changes in atmospheric transmission T(ζ,ϕ,z,t) derived from cloud and haze reflectivity show almost no average 14-year change from 55° S to 35° N but show an increase from 40° N to 60° N. This implies increased solar insolation at high northern latitudes that suggests positive feedback for global warming. TCO3 has increased at a rate of 2 % per decade for the latitudes between 60° S to 10° N changing to a decrease of 1 % per decade between 40° N to 60° N. The result is an average decrease in E(ζ,ϕ,z,t) at a rate of 2 % per decade in the Southern Hemisphere and an increase between 40° N to 60° N. For some specific sites (latitudes from 55° S to 45° N) there has been little or no change in E(ζ,ϕ,z,t) for the period 2005–2018. Nearly half the sites show the effects of both short- and long-term cloud change as well as total column ozone change. Synoptic EPIC data from the sunlit Earth are used derive ozone and reflectivity needed for global images of the distribution of E(ζ,ϕ,z,t) from sunrise to sunset centered on the Americas, Europe-Africa, and Asia. EPIC data are used to show the latitudinal distribution of E(ζ,ϕ,z,t) from the equator to 75° for specific longitudes. Dangerously high amounts of erythemal irradiance (12 < UV index < 18) are found for many low latitude and high-altitude sites (e.g., San Pedro, Chile (2.45 km), La Paz, Bolivia (3.78 km). Lower UV indices at some equatorial or high-altitude sites (e.g., Quito, Ecuador) are moderated by the presence of persistent cloud effects. High UVI levels (UVI > 6) are also found at most mid-latitude sites during the summer months. High levels of UVI are known to lead to health problems (skin cancer and eye cataracts) with extended unprotected exposures as shown in the extensive health statistics maintained by Australian Institute of Health and Welfare and the United States National Institute of Health National Cancer Institute.

Jay Herman et al.
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Status: open (until 16 Dec 2019)
Status: open (until 16 Dec 2019)
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
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Jay Herman et al.
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Short summary
The amount of erythemal irradiance reaching the Earth's surface has been calculated from the ozone and reflectivity data obtained from the OMI and DSCOVR/EPIC instruments. Changes in erythemal irradiance have been estimated for 14 years 2005–2018 showing areas with dangerously high levels of solar UV radiation.
The amount of erythemal irradiance reaching the Earth's surface has been calculated from the...