POSTER SESSION 3
15:30–17:30, Wednesday, September 16
Poster Session | 1 | 2 | 3 | 4 | Schedule at a Glance
ABSTRACT 1337 | POSTER 123
LIGHT AVAILABILITY DURING POLAR NIGHT
Primary production at high latitudes critically depends on light availability. Recent studies have demonstrated that only minimal light levels are required to sustain photosynthesis in Arctic microalgae. Most global models estimating light availability in the upper ocean assume that incoming irradiance originates primarily from sunlight reaching the surface during daytime. However, this assumption provides a simplified representation of light conditions during the polar night.
In this study, we assess whether light from sources other than daytime sunlight, namely twilight, moonlight, and night-sky background illumination, can provide sufficient irradiance to support primary production during the polar night. Subsurface light levels were estimated using a coupled atmosphere-ice-ocean pseudo-spherical radiative transfer model. Simulations were conducted from October to April over three consecutive winters across the pan-Arctic region. The model accounts for variability in cloud fraction and optical thickness, as well as snow depth and sea-ice thickness.
Preliminary results suggest that twilight may provide sufficient light to potentially exceed reported irradiance thresholds required to support photosynthetic growth during portions of the polar night. In contrast, moonlight and night-sky background illumination appear to provide negligible contributions, both in sea ice covered regions and in open ocean conditions.
Julien Laliberté, Fisheries and Oceans Canada, [email protected]
Marcel Babin, Université Laval, [email protected]
Poster Session | 1 | 2 | 3 | 4 | Schedule at a Glance
