IN ASSESSING BIOLOGICAL UV-B EFFECTS, NATURAL FLUCTUATIONS OF SOLAR-RADIATION SHOULD BE TAKEN INTO ACCOUNT

Daily and weekly fluctuations of PAR, UV-A, and UV-B have been continu ously monitored for 5 months in Ancient Korinthos, Greece (37 degrees 58' N, 23 degrees 0' E) using a calibrated instrument based on 3 sharp band sensors. Daily dose ranged between 521-12 006 kJ m(-2) for PAR; 52-1, 239 kJ m(-2) for W-A; and 0.66-22.5 kJ m(2) for UV-B. Weekly dos e ranged between 16 778-81 788 kJ m(-2) for PAR; 1 406-8 517 kJ m(-2) for W-A; and 18-151 kJ m(-2) for UV-B. UV-B/PAR and UV-A/PAR ratio dis tribution, however, does not follow closely PAR fluctuations. Generall y, the UV-B/PAR and UV-A/PAR ratios were high in bright light conditio ns (2.1x10(-3), 118x10(-3)) and low in darker weeks (0.9x10(-3), 63x10 (-3)). The UV-B/UV-A ratio exhibits smaller fluctuations with season ( 20x1x10(-3), 12x10(-3)). Attention is drawn to the effects of sudden c hanges in ambient radiation and to the ratios of UV-B, UV-A, and PAR.