Solar ultraviolet radiation in Croatia

Abstract:

From 1978 to 1998, the total ozone over Croatia decreased by 8%. Consequently, erythemally effective ultraviolet (UV) radiation has increased by 12%. According to the measurements conducted at the Geophysical Institute, Horvatovac, Zagreb, the highest typical UV index (UVI) for continental lowlands in Croatia is <7, while the radiation doze between 11 a.m. and 1 p.m. amounts to 4 minimal erythemal doses (MED). It is a sufficient dose to cause serious skin damage in case of excessive sun exposure without any sun protection. The 10 degrees difference in geographic latitude introduces a change of 1,3 UVI, whereas the erythemally effective radiation is amplified by 5% per kilometre of height. Ozone holes, i.e., stable areas with ozone concentration of less than 220 Dobson units (DU), have not been observed above Croatia. However, the so-called miniholes have been noticed. Miniholes are small unstable regions with decreased total ozone often lasting less than half a day. Because the average annual value of the total ozone of approximately 325 DU has been stable over the last five years, it may be concluded that the further deterioration of the ozone layer has stopped

Key words:
atmosphere; erythema; ozone; ultraviolet rays