Photosynthetically Active Radiation (PAR)
as Observed from Satellites

Department of Atmospheric and Oceanic Science
University of Maryland, College Park

Department of Meterology



Satellite Data

Available PAR Parameters


Data Distribution

Data Access





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Satellite Data Used

To derive PAR on global scale at a temporal resolution that resolves the diurnal cycle, global satellite data as available under the International Cloud Climatology Project (ISCCP ) (Schiffer and Rossow, 1985) were used. These were coupled with inference methods based on radiative transfer models, that infer PAR and related parameters, e. g., the conversion factor (CF), which represents the fraction of PAR in the total shortwave (SW) rad iation. The ISCCP satellite data include information on the state of the atmosphere and the surface, and as such, are currently considered as most appropriate for developing global scale inference algorithms, to derive surface parameters that are affected by clouds.

Satellite estimates of PAR provided at this Web site, are based on the following data sets:

  1. ISCCP C1, for period starting July 1983 to December 1988

  2. ISCCP D1, for period starting July 1983 to December 1994

  3. ISCCP DX, for period starting January 1990 to December 1992

Maintained by Banglin Zhang and Chuan Li