Development and calibration of a high dynamic range and autonomous ocean-light instrument to measure sub-surface profiles in ice-covered waters

• Published in: Applied Optics
• Main Authors: Schartmuller, Bernhard, Anderson, Philip, Mckee, David, Connan-McGinty, Stacey, Kopec, Tomasz Piotr, Daase, Malin Hildegard Elisabeth, Johnsen, Geir, Berge, Jørgen
• Format: Article in Journal/Newspaper
• Language: English
• Published: Optica Publishing Group 2023
• Subjects: VDP::Matematikk og naturvitenskap: 400::Fysikk: 430::Elektromagnetisme; akustikk; optikk: 434; VDP::Mathematics and natural scienses: 400::Physics: 430::Electromagnetism; acoustics; optics: 434; VDP::Teknologi: 500::Maskinfag: 570::Maskinteknisk energi- og miljøteknologi: 573; VDP::Technology: 500::Mechanical engineering: 570::Machinery energy and environmental technology: 573; Arctic; Arctic Ocean; ice covered waters
• Online Access: https://hdl.handle.net/10037/32006; https://doi.org/10.1364/AO.502437

The optical chain and logger (OptiCAL) is an autonomous ice-tethered observatory equipped with multiple light sensors for mapping the variation of light with depth. We describe the instrument and present an ensemble calibration for downwelling irradiance E PAR in [µmolm −2 s −1 ]. Results from a long-term deployment in the Arctic Ocean demonstrate that the OptiCAL can cover the high dynamic range of under-ice light levels from July to November and produce realistic values in terms of magnitude when compared to modeled surface irradiance. Transient features of raised light levels at specific depths associated with nearby leads in the ice underline the importance of depth-resolved light measurements.