Diffuse Shortwave IOP

24 September 2001 - 22 October 2001

Lead Scientist: Joseph Michalsky

Observatory: sgp, sgp

Scientific hypothesis: There is no absolute standard for diffuse horizontal irradiance measurements as there is for the direct beam irradiance. In lieu of an absolute standard, we were interested in the level of agreement that one could achieve by comparing a wide assortment of current instrumentation measuring skylight simultaneously for both clear and overcast situations. The main motivation for this need to improve the diffuse measurement is the persistent overestimation of clear-sky models relative to measurements.

Approach to test hypothesis: We sought voluteers to take part from the ARM, BSRN, and manufacturing communities. We chose early fall conditions because that time of year has been dependable with regard to having both clear and cloudy conditions needed for these comparisons. The pyranometers were mounted on five Sci-Tec trackers providing space for up to 14 instruments. The instruments were pre- and/or post-calibrated by their providers. Any corrections suggested by the providers were implemented before comparing data.

Activity Summary

Almost 4 weeks of data were acquired under mostly sunny skies. Ninety-two percent of the daylight hours had measureable direct beam radiation. Much of the sunny data included completely cloud free conditions. The trackers functioned perfectly. Clear-sky data included low to moderate aerosol cases with no high aerosol conditions sampled. Data recovery from the pyranometers was near 100%. Absolute cavity data were acquired on the first 7 days of the IOP. Some completely overcast data were available on a few days to test the instruments behavior relative to those conditions as well as the clear sky conditions. Data are still being analyzed.

Timeline

2012

Gueymard CA. 2012. "Clear-sky irradiance predictions for solar resource mapping and large-scale applications: Improved validation methodology and detailed performance analysis of 18 broadband radiative models." Solar Energy, 86(8), 10.1016/j.solener.2011.11.011.

2008

Reda I, D Myers, and T Stoffel. 2008. "Uncertainty Estimate for the Outdoor Calibration of Solar Pyranometers: A Metrologist Perspective." NCSLI Measure, 3(4), 10.1080/19315775.2008.11721448.

2005

Marsden DC, F Valero, and BC Bush. 2005. "Continental aerosol properties inferred from measurements of direct and diffuse solar irradiance." Journal of Geophysical Research – Atmospheres, 110(D20), D20204, 10.1029/2004jd005660.

2003

Michalsky JJ, R Dolce, EG Dutton, EG Dutton, M Haeffelin, G Major, JA Schlemmer, DW Slater, JR Hickey, WQ Jeffries, A Los, D Mathias, LJ McArthur, R Philipona, I Reda, and T Stoffel. 2003. "Results from the first ARM diffuse horizontal shortwave irradiance comparison." Journal of Geophysical Research: Atmospheres, 108(D3), 4108, 10.1029/2002jd002825.

Michalsky J, P Kiedron, Q Min, and L Harrison. 2003. Shortwave, clear-sky diffuse irradiance in the 350-1050 nm range: comparison of models with RSS measurements at the SGP ARM site in September/October 2001. In Proceedings of the Thirteenth Atmospheric Radiation Measurement (ARM) SCience Team Meeting, Ed. by D. Carrothers, Richland, WA: Department of Energy.

Michalsky JJ, P Kiedron, Q Min, and L Harrison. 2003. Shortwave, Clear-Sky Diffuse Irradiance in the 350-1050 nm Range: Comparison of Models with RSS Measurements at the Southern Great Plains ARM Site in September/October 2001. In Thirteenth Atmospheric Radiation Measurement (ARM) Program Science Team Meeting, Ed. by D. Carrothers, Richland, WA: U.S. Department of Energy.

2002

Powell D, S Kato, M Haeffelin, and O Dubovik. 2002. Clear-Sky Model and Measurement Comparisons from the First Diffuse Irradiance IOP - Fall 2001. In Proceedings of the Twelfth ARM Science Team Meeting, Ed. by D. Carrothers, Richland, WA: U.S. Department of Energy.


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Campaign Data Sets

IOP Participant Data Source Name Final Data
Robert Dolce Kipp & Zonen CM11 Order Data
Ellsworth Dutton EKO MS-801 Order Data
Martial Haeffelin CIMEL Order Data
Martial Haeffelin PSP Radiometer Order Data
John Hickey Eppley New B&W Order Data
William Jeffries Yankee Isothermal Pyranometer Order Data
Gyorgy Major Budapest University Order Data
David Mathias Carter-Scott design EQ08-A Order Data
Bruce McArthur Kipp & Zonen CM21 Order Data
Bruce McArthur Schenk Star Order Data
Rolf Philipona CM22 Order Data
Tom Stoffel Eppley 8-48 Order Data
Tom Stoffel NREL Eppley PSP Order Data
Francisco Valero RAMS Order Data