Application of distributed temperature sensing for mountain permafrost mapping

Abstract

Permafrost distribution in mountains is typically more heterogeneous relative to low‐relief environments due to greater variability in the factors controlling the ground thermal regime, such as topography, snow depth, and sediment grain size (e.g., coarse blocks). Measuring and understanding the geothermal variability in high mountains remains challenging due to logistical constraints. This study presents one of the first applications of distributed temperature sensing (DTS) in periglacial environments to measure ground surface temperatures in a mountain permafrost area at much higher spatial resolution than possible with conventional methods using discrete temperature sensors. DTS measures temperature along a fibre‐optic cable at high spatial resolution (i.e., ≤ 1 m). Its use can be limited by power supply and calibration requirements, although recent methodological developments have relaxed some of these restrictions. Spatially continuous DTS measurements at a studied rock glacier provided greater resolution of geothermal variability and facilitated the interpretation of bottom temperature of snowpack data to map patchy permafrost distribution. This research highlights the potential for DTS to be a useful tool for permafrost mapping, ground thermal regime interpretation, conceptual geothermal model development, and numerical model evaluation in areas of heterogeneous mountain permafrost.

Air Convection in the Active Layer of Rock Glaciers

“…Furthermore, active layer convection has also an influence on the assumed distribution of permafrost. Discontinuous permafrost is known to have heterogeneous distribution patterns, highly influenced by the ground cover (Harris and Pedersen, 1998;Gubler et al, 2011;Schneider et al, 2012;Harrington and Hayashi, 2019) and the results from this study underline the importance of this influence. Care has therefore to be taken in generalizing measured temperatures in the context of permafrost mapping, as ground temperatures are highly dependent on the ground cover and the corresponding active layer permeability.…”

Best Practice for Measuring Permafrost Temperature in Boreholes Based on the Experience in the Swiss Alps

“…Strings of digital sensors, however, are typically on one single cable, meaning that the entire chain fails in case of shearing. Distributed temperature sensing (DTS) using fiber optic cables have also been applied (Luethi and Phillips, 2016;Harrington and Hayashi, 2019), which would allow to measure temperatures over the whole length of the borehole. However, the high energy consumption and calibration requirements reported do not yet allow an implementation for continuous monitoring.…”

A Comparative Study of Active Rock Glaciers Mapped from Geomorphic- and Kinematic-Based Approaches in Daxue Shan, Southeast Tibetan Plateau

“…This is probably due to the lack of accurate constraints (i.e., air temperature and precipitation) on the permafrost estimation model. Furthermore, given that solar radiation, topography, and snow depth all have influences on the ground thermal regime [58], which control the occurrence of permafrost, using relatively simple empirical models to estimate large-scale permafrost distribution may somewhat be biased. In addition, ARGs move downslope and may reach the permafrostfree region.…”

“…In addition, ARGs move downslope and may reach the permafrostfree region. Due to the cooling effect of rock glaciers through their high porosity and storage of ice, rock glaciers can lead to a more favorable environment for permafrost occurrence than the surrounding terrain [58,59].…”