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SeaWiFS Surface Solar Irradiance (1994)

Surface solar irradiance and related products were obtained through the implementation of three generations of an algorithm in "Spatial and temporal variability of global surface solar irradiance" by Bishop and Rossow (1991) (see references below). The information was produced for the SeaWiFS project. The second generation (version 2) datasets (spanning eight years) are now archived at NCAR, and a year of the third generation (version 3) datasets from July 1983 to June 1984 is presently available (see below). Applications of the Bishop and Rossow datasets are found in papers by Mitchell et al. (1991), Liu et al. (1994), and Seager and Blumenthal (1994). The algorithm uses C1 data from the International Satellite Cloud Climatology Project (ISCCP), which combines data from multiple geostationary and polar orbiting meteorological satellites to provide a global view of the occurrence and optical properties of clouds. A high resolution (30-km) dataset obtained from ISCCP DX data is in production and five test days of data are currently available.

Atmospheric, cloud, and surface data from ISCCP are used as input with a fast scheme for computing clear-sky irradiance from the solar zenith angle, air properties, and surface reflectance. The scheme then uses simple cloud properties (cloud fraction, cloud optical thickness, and diffuse albedo) to produce total and photosynthetically active solar irradiance fields (Bishop and Rossow 1991; ISCCP Documentation of Cloud Data; Frouin et al. 1989). Input and output data fields are given in a 2.5° latitude and longitude grid.

The input data fields are ISCCP data:

  • Solar zenith angle (every 3hr)
  • Ozone, total precipitable water, surface pressure (daily)
  • Surface reflectance (every 3hr)
  • Cloud cover and optical thickness (every 3hr)
  • Land-water fraction
  • Snow and ice cover (every 5 days)

The output data fields are:

  • Clear sky irradiance
  • Total irradiance including clouds
  • Photosynthetically active solar irradiance fields

The output fields are available every three hours, and as daily and monthly averages. Daily and monthly averages of the input fields are also produced when adequate.

Available Data and Documentation

Version 2 and 3 documentation:
Draft dated Oct. 30, 1994, in a 1.6 MB PDF.
Version 2, monthly datasets:
Monthly averaged solar irradiance datasets are available for download as a single 3.9 MB netCDF file.
Version 2, complete production:
The complete production at daily and monthly resolution (July 1983 to June 1991) may be obtained from the NCAR Research Data Archive, dataset "DS741.0: Bishop's Surface Solar Irradiance derived from ISCCP" (link accessed 2018-08-30).
Version 3:
One year of data (July 83-Jun 84) is available in two formats. The data in SDS format, together with a FORTRAN program to read it, may be obtained here (213 MB TGZ). The monthly fields as unformatted real data are located in subdirectory c1real (23 MB TGZ). Warning: The real data were written as a sequential FORTRAN file in Unix. If the data are read in other system or language, the user may need to skip 4 bytes at the beginning and at the end of each record.
High-resolution (DX) data:
Five test days of photosynthetically active solar irradiance, including clouds, at 0.5° latitude and longitude resolution are available. Data in SDS format may be obtained here, (7 MB TGZ) and unformatted real data are located in subdirectory dxreal (4 MB TGZ). A short description of differences between the high resolution scheme and versions 2 and 3 is also available. The SDS format data are displayed with the North Pole at the top of the image for DX data (the South Pole is at the top for C1 data).
High-resolution (DX) movie:
A 550 kB MPEG movie of the five test days of DX data is available, showing one frame per day.


This project was led by Dr. James K.B. Bishop, now at the University of California, Berkeley.

Other scientists who participated in this project were Dr. William B. Rossow, Dr. Zulema Garraffo and Dr. Jamie McLaren.


Bishop, J.K.B., and W.B. Rossow 1991. Spatial and temporal variability of global surface solar irradiance. J. Geophys. Res. 96, 16839-16858.

Frouin, R., D.W. Lingner, C. Gautier, K.S. Baker, and R.C. Smith 1989. A simple analytical formula to compute clear sky total and photosynthetically available solar irradiance at the ocean surface. J. Geophys. Res. 94, 9731-9742.

Liu, W.T., A. Zhang, and J.K. Bishop 1994. Evaporation and solar irradiance as regulators of sea surface temperature in annual and interannual changes. J. Geophys. Res. 99, 12623-12637.

Mitchell, B.G., E. Brody, O. Holm-Hansen, C. McClain, and J.K. Bishop 1991. Light limitation of phytoplankton biomass and macronutrient utilization in the Southern Ocean. Linmol. Ocean. 36, 1662-1667.

Seager, R., and M.B. Blumenthal 1994. Modeling tropical Pacific Sea surface temperature with satellite-derived solar radiative forcing. J. Climate 7, 1943-1957.

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