sfccldgrid > Surface Cloud GridVAP Type(s) > Baseline

The estimated clear-sky fit total SW down.

The Surface Cloud Grid VAP uses as input the 15-minute output from the Shortwave Flux Analysis VAP (Long 2001, Long and Ackerman 2000, Long et al. 1999) from the Southern Great Plains (SGP) Central and Extended Facilities. It applies a multi-pass weighted sum analytic approximation technique (Caracena 1987), which uses Gaussian weighting and an imposed scale length, to interpolate to a 0.25 degree by 0.25 degree lat/long grid over the SGP domain. The output, like the input, includes only solar elevation angles of 10 degrees or greater.

The Surface Cloud Grid VAP produces gridded output for cloud fraction, the ratio of measured over clear-sky short wave total (both unshaded pyranometer and sum of direct + diffuse) and direct irradiance, the estimated clear-sky fit total shortwave irradiance, and the estimated clear-sky fit direct shortwave irradiance. The ratio measured over clear-sky direct shortwave, in conjunction with the total shortwave ratio and clear-sky total and direct irradiance, allows for component evaluation of the irradiance and cloud effects. These output variables were chosen because the intent is to use the Surface Cloud Grid VAP output for model comparisons, as well as climatological and statistical research.

For more details, see Surface Cloud Grid Version 2 (SFCCLDGRID2)
Value-Added Product: Description of Updates to Algorithm Operational Details in Version 2
technical report.


  • Fixed
  • AMF1
  • AMF2
  • AMF3


Reda I, J Zeng, J Scheuch, L Hanssen, B Wilthan, D Myers, and T Stoffel. 2012. "An absolute cavity pyrgeometer to measure the absolute outdoor longwave irradiance with traceability to international system of units, SI." Journal of Atmospheric and Solar-Terrestrial Physics, 77(March 2012), 10.1016/j.jastp.2011.12.011.

Sivaraman C. 2012. ARM Climate Research Facility Quarterly Value-Added Product Report Fourth Quarter: July 1–September 30, 2012. U.S. Department of Energy. DOE/SC-ARM-12-022.

Sivaraman C. 2012. ARM Climate Research Facility Quarterly Value-Added Product Report First Quarter: October 01-December 31, 2011. U.S. Department of Energy. DOE/SC-ARM-12-002.


Wu X, XZ Liang, and S Park. 2007. "Cloud-Resolving Model Simulations over the ARM SGP." Monthly Weather Review, 135(8), 10.1175/mwr3438.1.

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Damao Zhang
Pacific Northwest National Laboratory

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