Item: Are hand-held infrared thermometers and cameras useful for avalanche forecasting? For avalanche education?
-
-
Title: Are hand-held infrared thermometers and cameras useful for avalanche forecasting? For avalanche education?
Proceedings: International Snow Science Workshop Proceedings 2018, Innsbruck, Austria
Authors:
- Bruce Jamieson [ Snowline Associates Ltd., Calgary, Alberta, Canada ]
- Michael Smith [ Northwind Avalanche and Weather Services, Whitehorse, Yukon Territories, Canada ]
Date: 2018-10-07
Abstract: This paper presents new results for measuring the temperature of the snow surface (Tss) with hand-held infrared (IR) thermometers and of the pit wall with IR cameras, and identifies limitations including adjustment of IR thermometers to ambient temperature, as well as radiative and turbulent heat transfers during the exposure time of the pit wall. Avalanche forecasting operations have three objectives for Tss measurements: 1) an indication of near surface faceting, 2) day-to-day change in Tss, and 3) the current temperature difference from the melting point. We identify constraints that limit the value of IR or contact thermometers for these objectives. However, we propose that IR measurements of Tss over terrain variations in aspect, slope angle, windy vs sheltered, and sunny vs shady surfaces are valuable for teaching - and for developing an intuitive sense of - surface heat transfer over terrain. Avalanche forecasting operations are interested in the vertical temperature profile in the snowpack and especially in gradients adjacent to crusts. We took horizontal averages of IR pixels of a shaded pit wall and measured temperature changes of 1°C within a minute after exposing the pit wall. Temperature gradients also changed substantially within minutes. In contrast to the limitations of IR images of pit walls for avalanche forecasting, such images have considerable value for avalanche education. We show images that illustrate stronger temperature gradients in shallow areas and normal to the slope, heat flow along depth hoar chains, and the dependence of near surface temperature gradients on heat transfers at the surface.
Object ID: ISSW2018_P16.22.pdf
Language of Article: English
Presenter(s):
Keywords: infrared thermometer, infrared camera, snow surface temperature, snow temperature profile
Page Number(s): 1477-1481
-