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Photosynthetically available radiation at high latitudes
Author(s) -
Campbell Janet W.,
Aarup Thorkild
Publication year - 1989
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.1989.34.8.1490
Subject(s) - photosynthetically active radiation , albedo (alchemy) , irradiance , atmospheric sciences , environmental science , latitude , radiation , sunlight , flux (metallurgy) , solar irradiance , cloud albedo , climatology , cloud cover , geology , optics , physics , materials science , chemistry , photosynthesis , cloud computing , art , biochemistry , operating system , geodesy , performance art , computer science , metallurgy , art history
Low solar elevations at high latitudes result in two phenomena that affect the quantity and quality of light entering the sea. High surface reflectances significantly reduce the direct solar irradiance and, to a lesser extent, the global irradiance. Furthermore, there is an apparent spectral shift such that proportionately more blue (diffuse) light is transmitted and more red (direct) light is reflected by the sea surface. A model of photosynthetically available radiation (PAR) has been used to quantify these effects. The model was developed to predict daily broadband (400–700 nm) photon flux as a function of latitude and time of year for varying cloud‐free atmospheric conditions. Seasonal and spectral variability of the surface albedo is described at latitudes between 40° and 70°N. Ranges are established for surface albedo which encompass variability due to atmospheric turbidity and wind‐induced surface waves.