Preprints
https://doi.org/10.5194/tc-2023-41
https://doi.org/10.5194/tc-2023-41
20 Mar 2023
 | 20 Mar 2023
Status: this preprint is currently under review for the journal TC.

A low-cost and open-source approach for supraglacial debris thickness mapping using UAV-based infrared thermography

Jérôme Messmer and Alexander R. Groos

Abstract. Debris-covered glaciers exist in many mountain ranges and play an important role in the regional water cycle. However, modelling the surface mass balance, runoff contribution and future evolution of debris-covered glaciers is fraught with uncertainty as accurate information on small-scale variations in debris thickness and sub-debris ice melt rates is only available for a few locations worldwide. Here we present a customised low-cost UAV for high-resolution thermal imaging of mountain glaciers and a complete open-source pipeline that facilitates the generation of accurate surface temperature and debris thickness maps from radiometric images. First, a thermal orthophoto is computed from individual radiometric UAV images using structure-from-motion and multi-view-stereo techniques. User-specific calibration and correction procedures can then be applied to the raw thermal orthophoto to account for atmospheric and environmental influences that affect the radiometric measurement. The corrected thermal orhthophoto reflects spatial variations in surface temperature across the surveyed debris-covered area. Finally, a high-resolution debris thickness map is derived from the corrected thermal orthophoto using in-situ measurements in conjuction with an empirical or inverse surface energy balance model that relates surface temperature to debris thickness. Our results from a small-scale experiment on the Kanderfirn in the Swiss Alps show that the surface temperature and thickness of a relatively thin debris layer (ca. 0–15 cm) can be mapped with high accuracy. On snow and ice surfaces, the mean deviation of the mapped surface temperature from the melting point (∼0 °C) was 0.4 ±1.0 °C. The root-mean-square error of the modelled debris thickness was 1.2 cm. Through the detailed mapping, typical small-scale debris features and debris thickness patterns become visible, which are not spatially resolved by the thermal infrared sensors of current-generation satellites. The presented approach paves the way for glacier-wide high-resolution debris thickness mapping and opens up new opportunities for more accurate monitoring and modelling of debris-covered glaciers.

Jérôme Messmer and Alexander R. Groos

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on tc-2023-41', Sam Herreid, 22 May 2023
  • RC2: 'Comment on tc-2023-41', Anonymous Referee #2, 10 Jun 2023

Jérôme Messmer and Alexander R. Groos

Data sets

A low-cost and open-source approach for supraglacial debris thickness mapping using UAV-based infrared thermography (v1.0.0) [Data set] Jérôme Messmer and Alexander R. Grooos https://doi.org/10.5281/zenodo.7692542

Jérôme Messmer and Alexander R. Groos

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Short summary
The lower part of mountain glaciers is often covered with debris. Knowing the thickness of the debris is important as it influences the melting and future evolution of the affected glaciers. We have developed an open-source approach to map variations in debris thickness on glaciers using a low-cost drone equipped with a thermal infrared camera. The resulting high-resolution maps of debris surface temperature and thickness enable more accurate monitoring and modelling of debris-covered glaciers.