Relation between photosynthetically available radiation and total insolation at the ocean surface under clear skies1

• DOI: 10.4319/lo.1987.32.6.1370
• Publication Date: 2010-04-07T05:55:02Z
• Authors: Karen S. Baker; Robert Frouin
• Keywords: 0106 biological sciences; 13. Climate action; 11. Sustainability; 01 natural sciences

A radiative transfer model is used to investigate the relationship between photosynthetically available radiation, Epar(0+) and total incoming solar radiation, Etot(0+) at the ocean surface. The ratio of Epar(0+) to Etot(0+) lies between 0.42 and 0.50 for most clear sky conditions. The simulations indicate that the parameters governing the variability of Epar(0+): Etot(0+) are the solar zenith angle, the amount of water vapor in the atmosphere, and the aerosol optical thickness. The influence of ozone and other gaseous constituents is insignificant. Comparisons between model results and field data show close agreement. Given the solar zenith angle and an estimate of both the total water vapor amount and the aerosol optical thickness, Epar(0+) can be accurately predicted from Etot(0+) for studies of aquatic photosynthesis.