Midnight at the end of the world
journal contributionposted on 30.07.2019, 00:00 by Dimitri Acosta
During the austral summer, Antarctica receives 4 months of continuous sunlight, comparable to radiation levels in the tropics. In Taylor Valley, Antarctica, microbes in ice covered lakes convert this energy to photosynthesize beneath 3-6 meters (10-20 feet) of ice. Their activity is of great interest for the search of life on other planets. To measure gross primary productivity, holes are drilled through the ice cover, a process that is energetically expensive, time consuming and disruptive to the ecosystem. My research examines the distribution of surface Photosynthetic Active Radiation (s-PAR). High resolution 3D models of the valley created using LiDAR, combined with solar geometry and meteorological point measurements, allow mapping of s-PAR, improving the accuracy of primary production estimates. The panorama shows a 360-degree view of the Lake Fryxell basin around 3 am. The low solar angle casts shadows over most of the valley, except for the highest south facing slopes. The image captures the 3 sources of illumination for any surface: incident, diffuse and reflected. The ATV and the light sensor (foreground, bottom right) provide a sense of scale while the reflected light on the surface of the lake hints at the complexity of mapping s-PAR.