Penetration of ultraviolet B, blue and quanta irradiance into Svalbard waters

[摘要] Observations from August 1991 and 1993 of downward UV-B, blue and quanta irradiances, and of colour indices and Secchi disc depths in the Greenland Sea and the northern part of the Barents Sea, are presented. The UV-B irradiance (306 nm) is on average reduced to 10% of its surface value at 5 metres depth, and to 1% at 10 m. Blue irradiance (465 nm) is reduced to 10% at 21 m, and to 1% at 41 m. The integrated quanta irradiance obtains the same reductions at 16 m and 35 m, respectively. These penetration depths correspond to Ocean Water Type III in Jerlov's classification. They are about twice the values of May-June 1973 observed by Aas & Berge, but they are half the values observed in September 1979 by Højerslev. This variability may partly be seasonal, caused by the hydrological and light-climate cycles. The UV-B transparency of the Svalbard waters seems to be influenced by yellow substance from different freshwater run-offs, and there is probably no single relation between salinity and yellow substance c...

[学科分类] 自然科学（综合）