New Article- Warm-air entrainment and advection during alpine blowing snow events

Nikolas O. Aksamit and John W. Pomeroy
Published: September 1, 2020
The Cryosphere, volume14, issue 9, pages 2795–2807


Blowing snow transport has considerable impact on the hydrological cycle in alpine regions both through the redistribution of the seasonal snowpack and through sublimation back into the atmosphere. Alpine energy and mass balances are typically modeled with time-averaged approximations of sensible and latent heat fluxes. This oversimplifies nonstationary turbulent mixing in complex terrain and may overlook important exchange processes for hydrometeorological prediction. To determine if specific turbulent motions are responsible for warm- and dry-air advection during blowing snow events, quadrant analysis and variable interval time averaging was used to investigate turbulent time series from the Fortress Mountain Snow Laboratory alpine study site in the Canadian Rockies, Alberta, Canada, during the winter of 2015–2016. By analyzing wind velocity and sonic temperature time series with concurrent blowing snow, such turbulent motions were found to supply substantial sensible heat to near-surface wind flows. These motions were responsible for temperature fluctuations of up to 1 ∘C, a considerable change for energy balance estimation. A simple scaling relationship was derived that related the frequency of dominant downdraft and updraft events to their duration and local variance. This allows for the first parameterization of entrained or advected energy for time-averaged representations of blowing snow sublimation and suggests that advection can strongly reduce thermodynamic feedbacks between blowing snow sublimation and the near-surface atmosphere. The downdraft and updraft scaling relationship described herein provides a significant step towards a more physically based blowing snow sublimation model with more realistic mixing of atmospheric heat. Additionally, calculations of return frequencies and event durations provide a field-measurement context for recent findings of nonstationarity impacts on sublimation rates.

Read the full article here.

John Pomeroy consultant on award-winning Canadian author’s newest book

Author Leona Theis discusses Dr. Pomeroy’s contribution in this interview.

A&S: What is the research process like for your books? For example, you collaborated with USask scientist and alumnus Dr. John Pomeroy (BSC’83, PHD’88) for part of your new book. 
LT: For each of Sylvie’s lives, I wanted to connect with the spirit of the year it was set in—1974, 1979, 1984, etc. To do this I watched news clips, movie clips, and music videos. For example, the OJ Simpson chase plays a role, real and metaphorical, in one chapter. I watched and rewatched videos of the chase to remind me of the public mood that day and the way people were so caught up in the chase itself, in a bizarre, voyeuristic way. Another form of “research” consisted of sifting in a concentrated way through my own memories associated with specific years.
In some of her lives, Sylvie seems slow to grow into the responsibilities of adulthood. I wanted her, in later chapters, to take a more mature approach and to make connections between her own choices and the larger world. When we encounter her in the final chapter, she’s a grandparent concerned about environmental degradation and, wanting to play some part for the better, she returns to school as a grad student. She earns a place working on a research project modelled on Dr. Pomeroy’s work at Fisera Ridge in Kananaskis Country…