Atmospheric Radiation Measurement Climate Research Facility US Department of Energy

swfluxanal > Shortwave Flux AnalysisVAP Type(s) > Baseline • Guest

swfluxThe SW (shortwave) Flux Analysis VAP applies a clear-sky detection and fitting technique (Long and Ackerman 2000) to data from broadband SW radiometers located at the Southern Great Plains observatory. This technique uses hemispheric, broadband total- and diffuse-shortwave irradiance measurements to identify clear-sky periods using the known characteristics of typical clear-sky irradiance time series. These clear-sky estimates are then used to infer the effect of cloudiness on the measured downwelling SW at 1-minute resolution for daylight hours. The 1-minute resolution analysis also includes data quality assessment that goes beyond standard min/max/delta and component comparison testing. The SW Flux Analysis VAP also uses a technique (Long et al. 1999) to infer average fractional sky cover at 15-minute resolution for solar elevation angles 10° or greater.

For more details, see The Shortwave (SW) Clear-Sky Detection and Fitting Algorithm: Algorithm Operational Details and Explanations technical report.


  • Fixed
  • AMF1
  • AMF2
  • AMF3


brs: Broadband Radiometer Station

sirs: Solar and Infrared Radiation Station for Downwelling and Upwelling Radiation

skyrad: Sky Radiometers on Stand for Downwelling Radiation


Xie Y, M Sengupta, Y Liu, H Long, Q Min, W Liu, and A Habte. 2020. "A Physics-Based DNI Model Assessing All-Sky Circumsolar Radiation." iScience, 23(3), 10.1016/j.isci.2020.100893.


Burleyson CD, CN Long, and JM Comstock. 2015. "Quantifying Diurnal Cloud Radiative Effects by Cloud Type in the Tropical Western Pacific." Journal of Applied Meteorology and Climatology, 54(6), 10.1175/jamc-d-14-0288.1.
Research Highlight


Xie Y, Y Liu, CN Long, and Q Min. 2014. "Retrievals of cloud fraction and cloud albedo from surface-based shortwave radiation measurements: A comparison of 16 year measurements." Journal of Geophysical Research: Atmospheres, 119(14), 10.1002/2014jd021705.

Wu W, Y Liu, MP Jensen, T Toto, MJ Foster, and CN Long. 2014. "A comparison of multiscale variations of decade-long cloud fractions from six different platforms over the Southern Great Plains in the United States." Journal of Geophysical Research: Atmospheres, 119(6), 10.1002/2013jd019813.
Research Highlight


Long CN, LD Riihimaki, and LK Berg. 2012. Near-term Forecasting of Solar Total and Direct Irradiance for Solar Energy Applications. Presented at Fall American Geophysical Union Meeting. San Francisco, CA.

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Damao Zhang
Pacific Northwest National Laboratory

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