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All About the Pyrheliometers: 12th Annual IPC Conference

 
Published: 18 January 2016

Editor’s Note: Craig Webb, calibration technician at the Southern Great Plains site, sent this update.

Data quality of the measurements from radiometers requires accurate and regular recalibration traceable to the World Radiometric Reference, the international standard of solar radiation measurement.
Data quality of the measurements from radiometers requires accurate and regular recalibration traceable to the World Radiometric Reference, the international standard of solar radiation measurement.

Every 5 years the World Radiation Center/Physikalisch-Meteorologisches Observatorium Davos in Davos, Switzerland, hosts the International Pyrheliometer Comparison (IPC). Participants bring their instruments to the IPC and receive the transferred World Radiometric Reference (WRR) standard.

This year was the 12th annual conference, and my fourth time attending. The purpose of this conference is to provide participants with the WRR reduction factors for their absolute cavity radiometers, and other reference pyrheliometers, used throughout the world. People attend from all over the world, close to 90 people from around 40 countries.

We gather and set up our radiometers in hopes of receiving plenty of sunshine throughout the day so we can get a good calibration reference. The minimum number of reference points is around 300+ data points for a good calibration.

Pyrheliometers, also known as NIPs, are used to measure direct (beam) solar irradiance.
Pyrheliometers, also known as normal incidence pyrheliometers or NIPs, are used to measure direct (beam) solar irradiance.
I had the privilege to work with Eppley Laboratory, Inc., in assisting with three other participants’ Eppley AHF cavity radiometers and controllers when they began to have trouble. We worked to get them up and working and let one use the other side of our tracker so their radiometers could keep running after their tracker quit.

As usual, I had another great experience at the IPC conference.