Variations of erythemal ultraviolet irradiance and dose at Tartu/Tõravere, Estonia

Climate Research

K. Eerme¹  R. Koppel¹  U. Veismann¹ 

关键词: Erythemal ultraviolet radiation;    UV dose;    UV index;    Atmospheric turbidity;    Total ozone;    Cloud factor;    Relative sunshine duration;   

DOI  :  10.3354/cr022245

来源: Inter-Research Science Publishing

【 摘 要 】

ABSTRACT: The variations of erythemally weighted ultraviolet (UV) irradiance and its relationships with atmospheric characteristics during 3 annual cycles (1998-2000) at 1 site (Tõravere, Estonia; 58.3°N, 26.5°E; 70 m above sea level) were studied, withthe further aim to estimate the erythemal doses for past years. In clear sky conditions the daily erythemal dose and noon irradiance exhibit total-ozone-related asymmetry in the annual cycle, with 27% lower values at spring equinox than at autumnalequinox. The clear sky ratio of erythemally weighted to broadband (300 to 3000 nm) irradiance increases from (0.5 ± 0.25) × 10^-4 to (2 ± 0.1) × 10^-4 with an increase in solarelevation from 10° to 55°. In overcast low cloudiness conditions this ratio is higher. A simple empirical method to estimate the summer half-year erythemal dose for past years is proposed, and the doses were calculated for 1967-2000. A sharp drop insummer half-year sunshine duration and erythemal dose was found around 1975, with a following quasi-linear recovery to the values met in 1967-1975. A comparison with the measured and Total Ozone Mapping Spectrometer (TOMS)-derived data is provided for1998-2000. In the fine summer of 1999 and the Œnormal¹ one of 2000, the measured, estimated and TOMS-derived half-year doses agreed to within 0.7%. In the extremely cloudy summer of 1998, the difference between the measured and estimated values was 1.7%and between the measured and TOMS-derived values 6%.

【 授权许可】

Unknown