Reconstruction of daily solar UV irradiation from

Authors: Jürgen Junk Uwe Feister Alfred Helbig

Publish Date: 2007/02/22

Volume: 51, Issue: 6, Pages: 505-512

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Abstract

Longterm records of solar UV radiation reaching the Earth’s surface are scarce Radiative transfer calculations and statistical models are two options used to reconstruct decadal changes in solar UV radiation from longterm records of measured atmospheric parameters that contain information on the effect of clouds atmospheric aerosols and ground albedo on UV radiation Based on earlier studies where the longterm variation of daily solar UV irradiation was derived from measured global and diffuse irradiation as well as atmospheric ozone by a nonlinear regression method Feister et al 2002 Photochem Photobiol 76281–293 we present another approach for the reconstruction of time series of solar UV radiation An artificial neural network ANN was trained with measurements of solar UV irradiation taken at the Meteorological Observatory in Potsdam Germany as well as measured parameters with longterm records such as global and diffuse radiation sunshine duration horizontal visibility and column ozone This study is focussed on the reconstruction of daily broadband UVB 280–315 nm UVA 315–400 nm and erythemal UV irradiation ER Due to the rapid changes in cloudiness at midlatitude sites solar UV irradiance exhibits appreciable shortterm variability One of the main advantages of the statistical method is that it uses doses of highly variable input parameters calculated from individual spot measurements taken at short time intervals which thus do represent the shortterm variability of solar irradianceWe gratefully acknowledge the support given by the European project “StratosphericClimate Links with Emphasis on the Upper Troposphere and Lower Stratosphere SCOUTO3 Activity 4 UV radiation” activity leaders A Bais and G Seckmeyer Further we would like to mention the support of the European COST726 action “Long term changes and climatology of UV radiation over Europe” to which results of our model calculations and input data have been submitted The contributions of M Woldt who derived daily totals of UV radiation from Brewer spectra and K Behrens who provided the global and diffuse irradiance values are also acknowledged

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