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Field Report

Dry Snow Zone

Greenland

Seasons: 2014, 2015, 2017

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Objectives

The objective of the field work was to gather observations required for the development of a 3D finite element time-dependent model of the McMurdo Shear Zone (SZ) stress fields. To accomplish the objective, the science team needed to perform ground penetrating radar (GPR) surveys both within and outside the shear zone. This area is of high scientific interest in understanding glacial flow.

 

Background

Shear zones are caused by velocity gradients in glacier and ice sheet flow that result in high stresses and therefore a high concentration of crevasses. These areas are dangerous to study by traditional means due to the prevalence of crevasses. Skiing and snowmobiling in this area is out of the question due to the high risk of a snowbridge collapse. The state of the art method of crossing these zones is to attach a GPR unit on a boom in front of a tracked vehicle and monitor the real time output. This is highly dangerous, as operator error could result in loss of life and loss of the vehicle. It is also tedious and slow work, seeing as when a crevasse blocks the path, forward progress halts, and the operators must probe the extents of the crevasse to find a route past. Therefore, scientific studies of these areas are limited.

 

Solution

The solution was to use a lightweight robot to survey the area. The founders of Polar Research Equipment were included on the later seasons of this grant as robot specialists to operate the GPR rover. Over the course of three field seasons, the 70 kg robot collected hundreds of kilometers of GPR data in this dangerous shear zone. The robot has a low enough ground pressure that it can traverse over relatively thin snowbridges with low risk of breaking through. While this is the main safety advantage of the robot, the autonomous data collection proved to have a number of other benefits. For example, after about 15 km of data collection, the robot would return to camp, the data would be downloaded, and the robot would be sent out for another 15 km survey. While the robot is out collecting more data, the team could start analyzing the downloaded data to ensure that the system was set up properly. In one instance, the analyzed data revealed a potential marine ice intrusion that called for a more detailed survey. Therefore, the robot’s route was changed to a more detailed grid over this point of interest due to data collection and analysis happening in parallel.

 

Future Work

Due to the success of these field seasons, Polar Research Equipment has been contacted for further work in the McMurdo Shear Zone. The South Pole Traverse team has expressed interest in our services for performing a detailed GPR survey of the area in order to safely build a new road across this highly crevassed terrain.