14:00–14:15 | ABSTRACT 1282
HODR: DEVELOPMENT OF A HIGH DYNAMIC RANGE SPECTROMETER FOR SENSITIVE MEASUREMENT OF BIOLOGICALLY RELEVANT ARTIFICIAL LIGHT POLLUTION
Natural variability in light conditions govern the life cycles and behaviours of marine organisms even at extremely low intensities, and artificial light at night (ALAN) has been shown to have major impacts on this natural regulation, with effects propagating through the trophic web. Accurate measurement of these natural cycles and the disturbance caused by human activity is key to modelling these effects, biological responses, and possible mitigation strategies. Existing field instrumentation sacrifices either sensitivity or spectral resolution for this task. We have developed a high sensitivity irradiance spectrometer system for field deployment called HODR (High Optical Dynamic Range). With active cooling to -70°C, and integration times up to more than 15 minutes, HODR can characterise extremely low light with sub-nanometre spectral resolution. Using radiative transfer modelling, the surface light conditions could be extended into the water column to gain an unprecedented picture of the depth and magnitude of ALAN from various sources. The system has been deployed successfully several times, including on an urban rooftop, mounted on a small research vessel, and a three-month deployment in a light observatory in Svalbard. We present the process of developing and calibrating HODR, and the results of these deployments – dramatic irradiance changes over 6 orders of magnitude as the arctic transitions into polar night, varying reflectance of street lighting as atmospheric conditions change, and spectacular multicoloured Aurora Borealis. It is hoped that this advance in sensitivity and spectral resolution will enable further research on biological responses to artificial light pollution.
Ruairidh Wallace, University of Strathclyde, [email protected], https://orcid.org/0009-0000-9830-2178
David McKee, University of Strathclyde, [email protected], https://orcid.org/0000-0001-8023-5923
