Multidisciplinary
study on the role of glacier crevasses in context of rising air temperatures
Richard Hann (1,2), Marius O. Jonassen (2), Andrew
Hodson (2)
(1) Norwegian University of Science and Technology
(2) University
Centre in Svalbard
Poster Contact
Richard Hann, PhD
Richard.Hann@ntnu.no
Postdoc researcher
Norwegian University of Science and Technology
––––
Poster References
[1]: Arthur Garreau, Validation
and Application of Novel Wind Estimation Methods with Quadcopter UAVs in the
Arctic, master thesis, 2020, NTNU / UNIS / École nationale de la
météorologie (ENM).
[2]: Armin Dachauer, Aerodynamic Roughness Length of Crevassed Tidewater Glaciers from UAV Mapping, master thesis, 2020, NTNU / UNIS / ETH Zürich.
[3]:
Max Nüßle, Heat
Transfer Simulations of Crevassed Glaciers, master thesis, 2021, Uni
Stuttgart / UNIS / NTNU.
––––
Further Links
––––
Abstract
Crevasses are altering the
surface roughness of glaciers. A crevassed glacier surface has a larger surface
area and offers more obstacles for the wind compared to a smooth surface. These
two effects can increase the rate at which the glacier body is exchanging heat
with the atmosphere. In other words, crevasses increase the aerodynamic surface
roughness lengths and thus increase turbulent heat fluxes. In the context of
rapidly rising air temperatures in the Arctic, this is may be a potent
mechanism to increase glacier melt rates.
In our research, we are following
a multidisciplinary approach to investigate the role of crevasses on
aerodynamic roughness lengths. We are following three, that will be presented.
The first approach uses drone-based mapping techniques to generate
high-resolution digital elevation models (DEMs) of crevassed glaciers in
Svalbard. These DEMs are then used to calculate aerodynamic roughness lengths
using several different semi-empirical models that have been developed
previously in the literature.
The second approach uses the
same DEMs to conduct computational fluid dynamic (CFD) simulations to directly
simulate the atmospheric boundary layer near the glacier surface. These
simulations show how katabatic winds interact with the crevasses surface and
how the increased turbulence influences heat transfer rates with the
atmosphere.
The third approach uses a
novel method to use a multirotor drone for wind measurements based on its
inertial measurement unit (IMU) data. Pitch angle, yaw angle, and thrust
variables can be used to estimate wind speed and wind direction while the drone
is holding its position. Wind profile measurements above crevassed glacier
surfaces can be used to estimate the aerodynamic roughness lengths from their
logarithmic form.
In summary, we will present
three novel methods from the fields of glaciology, meteorology, computational
fluid dynamics, and drone technology for the application of crevassed glaciers.