Long-term evaluation of the calibration of YES UVB-1 broadband radiometers of the Central UV Calibration Facility (1994-2005) and the suite of UV radiometers in the USDA UV Monitoring Network

The U.S. Central UV Calibration Facility at the National Oceanic and Atmospheric Administration of the Earth Systems Laboratory calibrates Yankee Environmental System (YES) UVB-1 broadband radiometers for the USDA UV Monitoring and Research Program. The Central UV Calibration Facility has three reference YES UVB-1 broadband radiometers that operate in the field at the Table Mountain Test Facility (TMTF). These three reference broadband radiometers are run simultaneously against a reference spectroradiometer developed by Atmospheric Science Research Center at the State University of New York, Albany. The temporal stability will be shown of the erythema calibration factors of the reference YES UVB-1 radiometers under clear skies from 1994 until 2005. The USDA UV Monitoring and Research Program has 51 UV broadband radiometers that are characterized for spectral response and cosine response, and calibrated approximately once every 1-2 years by the CUCF starting in 1997. The average annual changes in the calibration are given for the 51 USDA YES UVB broadband radiometers.