The 1997 North American Interagency Intercomparison of Ultraviolet Spectroradiometers Including Narrowband Filter...

Area of Science:

• Atmospheric Science
• Radiometry
• Environmental Monitoring

Background:

• Stratospheric ozone depletion necessitates accurate monitoring of solar ultraviolet (UV) irradiance.
• Government agencies established UV monitoring networks across North America.
• The North American Intercomparison of Ultraviolet Monitoring Spectroradiometers (NAIUVMS) addresses data comparability.

Purpose of the Study:

• To assess the accuracy of spectroradiometers in measuring solar UV irradiance.
• To compare measurements from different UV monitoring networks.
• To evaluate instrument performance and identify areas for improvement.

Main Methods:

• Instruments underwent characterization for wavelength accuracy, bandwidth, stray-light rejection, and spectral irradiance responsivity.
• Outdoor spectral irradiance responsivity was determined multiple times to assess temporal stability.
• Synchronized solar irradiance spectral scans were conducted over several days.

Main Results:

• Spectroradiometers (excluding filter radiometers) showed a relative standard deviation of ±4% for wavelengths > 305 nm.
• Including filter radiometers, the relative standard deviation remained ±4% for filter functions > 300 nm.
• Measurements were processed using NIST-traceable standards and a convolution technique for bandwidth correction.

Conclusions:

• The intercomparison confirmed good agreement among spectroradiometers for solar UV irradiance measurements.
• The results support the reliability of current UV monitoring networks.
• Further intercomparisons are valuable for maintaining data quality and consistency.