Radiometer Response Time and Irradiance Measurement Accuracy

This study evaluates the response times of three types of ISO 9060 First Class pyrheliometers in the laboratory, and more generally, investigates the stabilization of their output signals in response to step changes in irradiance. Observations are similar to, but much more detailed than our previous testing of pyranometers. The link between response time and measurement accuracy in various situations is discussed, and a model of the time-dependent instrument response is developed which can be used to explore the achievable accuracy in specific measurement contexts.