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Calibration of the Odyssey Photosynthetic Irradiance Recorder for Absolute Irradiance Measures
Citation:
Shaffer, J. M. AND J. J. BEAULIEU. Calibration of the Odyssey Photosynthetic Irradiance Recorder for Absolute Irradiance Measures. JOURNAL OF FRESHWATER ECOLOGY. Taylor & Francis Group, London, Uk, 27(4):599-605, (2012).
Impact/Purpose:
To inform the public.
Description:
Researchers are increasingly interested in measuring hotosynthetically active radiation (PAR) because of its importance in determining the structure and function of lotic ecosystems. The Odyssey Photosynthetic Irradiance Recorder is an affordable PAR meter gaining popularity among aquatic ecologists. Unlike more expensive PAR meters, the Odyssey Recorder must be user calibrated. We found the suggested calibration procedure can produce inaccuracies of <1% - >300%. We recommend a revised calibration procedure utilizing measurements taken across a range of PAR irradiance intensities with a 1 second scanning interval. This procedure is unaffected by short-term fluctuations in solar intensity which can be an issue when longer scanning intervals are used. Furthermore, this procedure produces a multi-point calibration curve that can be fit with linear regression yielding a calibration factor and standard error. Accuracy may not important for studies which use individual sensors to assess relative PAR availability across space or time; however, accuracy is critical for investigations which seek to compare PAR measurements made with multiple sensors or to build quantitative relationships between process and PAR
