Data from the National Science Foundation-sponsored monitoring sites of ultraviolet and visible radiation in Antarctica and Barrow, Alaska will be used to determine the relationship between biologically effective ultraviolet radiation, ozone abundance and cloud effects. Satellite data on ozone abundance and cloud properties will be used in a radiative transfer model to compute the ultraviolet radiation budget at these sites. Comparison with the ground-based measurements will be made to determine the feasiblity of assessing the biospheric ultraviolet radiation environment in the polar regions from space. Climatological estimates of the surface albedo will then be used to assess how the ultraviolet and visible radiation budget varies with season throughout the Antarctic and Arctic regions. The relative magnitudes of UVB (280-320 nm), UVA (320-400 nm), and photosynthetically active radiation (PAR, 400-700 nm) will be assessed as a function of latitude and season and climatological parameters (turbidity, cloud cover, etc.). Finally, a coupled atmosphere/ocean radiation model will be used to estimate the amount of ultraviolet and visible radiation penetrating to various levels in the polar ocean as a function of ocean productivity.