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