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

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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.

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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.