During the two-year project period, the fellow (T. Shaw) has conducted several field campaigns in the Swiss Alps using low-cost, yet robust meteorological instrumentation in order to explore ongoing questions regarding the role of the glacier boundary layer in determining near-surface air temperatures. The high-resolution data from several on-glacier weather stations yielded interesting findings related to inter-glacier differences exposed to the same regional conditions but also complimented the wealth of data available to a previously instrumented glacier (Haut Glacier d’Arolla). Regarding the latter, these more recent observations provide new evidence as to the decay of the boundary layer for a small glacier, highlighting the complex and non-linear response of a glacier to current and future climate. These results, published in the open-access journal Geophysical Research Letters (Figure 1), demonstrate that, due to the presence and eventual decay of the glacier boundary layer cooling effect, static parameterizations of air temperature biases over glaciers will over-simplify the future of glacier melt and retreat.
Further work related to three glaciers in the Pennine Alps of Switzerland have highlighted how strong the inter-glacier differences of near-surface cooling can be, especially in the context of the extreme summer heat under which the measurements in 2022 were made. This work, recently submitted to the open-access Journal of Geophysical Research: Atmospheres, demonstrates the strong control of glacier exposure to synoptic and valley winds in determining the near-surface cooling and resultant sensible heat transfer to melt ice (Figure 2). This segment of the project makes steps toward a generalizable parameterization of air temperature on glaciers in that it shows that glacier size alone is not enough to explain the inter-glacier differences in sensitivity to atmospheric temperature changes. The extreme 2022 summer provides an indication of likely future climate and further highlights the issues related to stationarity and appropriateness of single parameters used to model regional and global melt and retreat of glaciers.
These new findings work to support the development of a generalizable parameterization of on-glacier air temperature for melt modelling that is ongoing. During the TEMPEST project the fellow has made progress in compiling a new, global dataset of available on-glacier weather station data into a standardized and quality-controlled format. To date, data from ~190 case studies (>90 individual glaciers for multiple summers) have been processed (> 1.5 million hourly data points) in order to explore some of the previously identified controls for on-glacier temperature variability (Figure 3). First-order controls have been established and ongoing international collaborations are helping to further develop the robustness of work that is planned for publication in a high-impact journal.
Data gathered as part of the TEMPEST project has been made publicly available through open-access repositories on Zenodo and the fellow has additionally made efforts to compile and curate past datasets that he has gathered in order to enhance open data science. The datasets are also described and provided freely on the public webpage for the TEMPEST project (tempestglacier.com).
The fellow has presented work related to global analyses (Figure 3) and temporal changes for glacier boundary layers (Figure 1) at large international conferences specific to mountain environments (IMC, September 2022) and geosciences (EGU, April 2023) and interacted with scientific audiences within both glaciological and atmospheric sub-disciplines. Networking at these events led to the fellow’s contribution in the ongoing boundary layer experiments on the Austrian glacier, Hintereisferner (HEFEX II).
