Mapping Surface Temperatures on a Debris-Covered Glacier With an Unmanned Aerial Vehicle

Frontiers in Earth Science

Désirée Treichler²  Jakob F. Steiner³  Walter W. Immerzeel³  Philip D. A. Kraaijenbrink³  Joseph M. Shea⁴  Inka Koch⁵  Maxime Litt⁵ 

[1] Centre for Hydrology, University of Saskatchewan, Saskatoon, SK, Canada;Department of Geosciences, University of Oslo, Oslo, Norway;Department of Physical Geography, Faculty of Geosciences, Utrecht University, Utrecht, Netherlands;Geography Program, University of Northern British Columbia, Prince George, BC, Canada;International Centre for Integrated Mountain Development, Kathmandu, Nepal;

关键词: UAVs;    debris-covered glaciers;    surface temperature;    thermal infrared imaging;    Himalaya;   

DOI  :  10.3389/feart.2018.00064

来源: DOAJ

【 摘 要 】

A layer of debris cover often accumulates across the surface of glaciers in active mountain ranges with exceptionally steep terrain, such as the Andes, Himalaya, and New Zealand Alps. Such a supraglacial debris layer has a major influence on a glacier's surface energy budget, enhancing radiation absorption, and melt when the layer is thin, but insulating the ice when thicker than a few cm. Information on spatially distributed debris surface temperature has the potential to provide insight into the properties of the debris, its effects on the ice below and its influence on the near-surface boundary layer. Here, we deploy an unmanned aerial vehicle (UAV) equipped with a thermal infrared sensor on three separate missions over one day to map changing surface temperatures across the debris-covered Lirung Glacier in the Central Himalaya. We present a methodology to georeference and process the acquired thermal imagery, and correct for emissivity and sensor bias. Derived UAV surface temperatures are compared with distributed simultaneous in situ temperature measurements as well as with Landsat 8 thermal satellite imagery. Results show that the UAV-derived surface temperatures vary greatly both spatially and temporally, with −1.4 ± 1.8, 11.0 ± 5.2, and 15.3 ± 4.7℃ for the three flights (mean ± sd), respectively. The range in surface temperatures over the glacier during the morning is very large with almost 50 °C. Ground-based measurements are generally in agreement with the UAV imagery, but considerable deviations are present that are likely due to differences in measurement technique and approach, and validation is difficult as a result. The difference in spatial and temporal variability captured by the UAV as compared with much coarser satellite imagery is striking and it shows that satellite derived temperature maps should be interpreted with care. We conclude that UAVs provide a suitable means to acquire surface temperature maps of debris-covered glacier surfaces at high spatial and temporal resolution, but that there are caveats with regard to absolute temperature measurement.

【 授权许可】

Unknown