Correcting PAR Data from Photovoltaic Quantum Sensors on Remote Weather Stations on the Great Barrier Reef

Abstract

The study addresses a network of remote weather stations on the Great Barrier Reef (GBR) that house Licor192 quantum sensors measuring photosynthetically active radiation (PAR) above water. There is evidence of significant degradation in the signal from the sensors after a 2-yr deployment. Main sources of uncertainty in the calibration are outlined, which include degradation of the photodiode, soiling of the sensors by dust and salt spray, cosine responses, and sensitivity to air temperature. Raw PAR data are improved using correction factors based on a cloudless PAR model. Uncertainties in cosine responses of the instrument are low but significant errors may occur if the supporting platform is misaligned and not horizontal. A set of recommendations are provided to improve the quality of the PAR data.