Photosynthetically available radiation: a practical approach for global applications
An accurate and complete description of the light field at the ocean surface in the spectral domain 350-700 nm is useful information for ocean heat budgets and biological and optical studies. Modelling of the atmospheric radiative transfer needs to represent a complex set of phenomena, and sound simplifications are necessary to obtain multi-year global time series. This report presents an approach combining a minimum representation of the light characteristics and a relative numerical simplicity. The result is the light field in the visible domain (photosynthetically available radiation, PAR), including a spectral resolution for both direct and diffuse components. Model inputs are all available as satellite or meteorological products. The model is first described for situations of clear sky. Then, the modelling of the clud effects on both the intensity and shape of the irradiance spectrum is presented. As the equations are defined, the geophysical products required to force the model are identified. The results of the comparison with independent products as well as with surface measurements give confidence in the outputs.
Bibliographic Reference: EUR 21016 EN (2003), 58 pp. Free of charge
Availability: Available from European Commission, JRC Knowledge Management Unit, Ispra (IT) Tel: +39 033278 9843 or +39-033278-9864 Fax: +39-033278-9623 E-mail: firstname.lastname@example.org
Record Number: 200417434 / Last updated on: 2004-03-09
Original language: en
Available languages: en