Posters

Poster Session 2, Tuesday,  October  4, 10:40–12:40

Poster 66

Midnight Sun to Polar Night: Modelling seasonal light in the Barents Sea

Polar regions are defined by the extreme seasonality of their light fields. Animals and plants in polar regions respond to light driven stimuli throughout the year, even in the apparent darkness of the polar night. Standard light field models tend to be restricted to scenarios where the solar elevation is at or above the horizon. However, there is growing evidence of important biological responses to light when the sun is below the horizon, including diffuse solar sky glow, moonlight and background irradiance from stars and the aurorae. We have developed a fast, computationally inexpensive model of hyperspectral irradiance (HEIMDALL) that includes solar (above and below horizon), lunar, and cosmic contributions (not including the aurora) and has capacity to deal with cloud cover. This model has been validated against surface irradiance data collected at the Arclight Observatory outside Ny Ålesund, Svalbard. Using a bio-optical model developed for the Barents Sea, we are able to accurately predict underwater hyperspectral downwards irradiance as a function of depth for both homogeneous and inhomogeneous water columns. This has been validated against Hydrolight radiative transfer simulations and corresponding estimates of PAR have been validated against data collected on a long term glider transect. HEIMDALL extends the range of light field conditions that can be simulated into night time scenarios that are important for polar night and artificial light at night (ALAN) studies, and provides hyperspectral information for light levels far below what can be measured with conventional instrumentation.

David McKee, University of Strathclyde, [email protected], 0000-0001-8023-5923 

Stacey Connan-McGinty, University of Strathclyde, [email protected] 

Neil Banas, University of Strathclyde, [email protected] 

Jorgen Berge, UiT The Arctic University of Norway, [email protected]

Finlo Cottier, Scottish Association for Marine Science, [email protected] 

Stephen Grant, Norwegian University of Science and Technology (NTNU), [email protected] 

Geir Johnsen, Norwegian University of Science and Technology (NTNU), [email protected] 

Tomasz Kopec, UiT The Arctic University of Norway, [email protected] 

Marie Porter, Scottish Association for Marine Science, [email protected]