Snow Coupled Distributed Acoustic Sensing for Intrusion Detection of
Polar Bears in Arctic Camps
Abstract
Everchanging arctic climate conditions continue to negatively impact the
habitat of the polar bear. The changes cause them to search for food
outside of their traditional hunting grounds and potentially encounter
humans in locations where interactions weren’t previously documented.
One such occurrence in 2018 found a female polar bear at Summit Science
Station near the center of the Greenland Ice Sheet (GIS) which is over
300 km from the closest traditional food source. In an attempt to
mitigate the safety concern posed by potential interactions, the U. S.
National Science Foundation-Office of Polar Programs-Arctic
Sciences-Research Support and Logistics Program (NSF-OPP-ARC-RSL) has
sponsored an effort to evaluate new technologies for use as a perimeter
monitoring tool around remote arctic research camps. Distributed
acoustic sensing (DAS), a technology often used for perimeter detection
in high security areas, uses fiber optic technology to sense mechanical
vibrations due to seismic or acoustic sources, including foot-steps. The
systems are typically very sensitive and can not only be used to detect
an intrusion, but often characterize the type of intrusion. Sensor
ground coupling in soil is well understood for these systems; however,
use in arctic conditions with direct snow coupling is not. A range of
human foot pressures was used to simulate foot pressures of various
sized polar bears. The very large surface area of the polar bear foot
when considered over three points of contact for a walking quadruped,
results in a similar foot pressure when compared to the single point of
contact of a walking human. Using polar bear analogues, we demonstrate
DAS performance in direct snow coupling, evaluate the loss in system
sensitivity due to increasing snow pack and assess the effects of
extreme cold on fiber optic sensors down to -70 degrees Celsius.