Author Archives: Jin

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

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Nikolas O. Aksamit and John W. Pomeroy
Published: September 1, 2020
The Cryosphere, volume14, issue 9, pages 2795–2807
DOI: https://doi.org/10.5194/tc-14-2795-2020

Abstract:

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

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

Excerpt:
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…

Dr. John Pomeroy to offer webinar on Mountain Snow Hydrology, September 3, 2020

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September, 3, 2020
6am -7:30am, CST

This presentation will review advances in understanding the snow processes that control the hydrology of high mountain areas: snow accumulation, redistribution by wind and gravity, interception by forest canopies, sublimation, snowmelt and runoff generation. It will discuss how these processes operate in various high mountain environments, how they can be measured and show through computer simulations how they work together at the headwater catchment scale to generate downstream water resources. Snow processes are particularly sensitive to climate warming and so their role in controlling the vulnerability of water resources to climate change will be highlighted.

Register here.

Dr. Corinne Schuster-Wallace to take part in national sepsis study

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USask water and health researcher part of new national network studying sepsis

July 24, 2020
Chris Putnam, College of Arts & Science News

A researcher in the University of Saskatchewan’s (USask) College of Arts and Science is one of the collaborators on a new national network to study deadly blood infections.

On July 23, the Canadian Institutes of Health Research (CIHR) announced the creation of Sepsis Canada, a new research network that will improve the treatment of sepsis, a life-threatening condition that can result from infection.

Dr. Corinne Schuster-Wallace (PhD), a faculty member in the College of Arts and Science’s Department of Geography and Planning, is a co-investigator on the project. Dr. Joann Kawchuk (MD) of the USask College of Medicine is another co-investigator.

Read the full article here.

John Pomeroy discusses the suspension of Alberta water monitoring on CBC radio

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Trailbreaker with Loren McGinnis

Aired on CBCListen, July 21, 2020

“Last week, leaked emails revealed that Alberta suspended its water monitoring without notifying the NWT. That’s in violation of a bilateral water agreement signed by the Government of the Northwest Territories and the government of Alberta in 2015. Monitoring have been paused due to public-health concerns raised by the COVID-19 pandemic.”

Hear the discussion between John Pomeroy and former NWT environment minister Michael Miltenberger here.

Read the related article, “Suspending water quality monitoring during pandemic a ‘serious oversight,’ says expert” from CBC News here.

Greta Thunburg speaks of her visit to the Athabasca Glacier with John Pomeroy

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Released On: 10 Jul 2020

Greta Thunberg describes the remarkable and tumultuous past year of her life on a BBC podcast. Hear her description of her visit to the Athabasca Glacier and discussions with John Pomeroy on chapter 6 (30:06).

Read the Time Magazine article: Six Months on a Planet in Crisis: Greta Thunberg’s Travel Diary from the U.S. to Davos, for a full transcription of the podcast here.

USask ranked No. 1 in Canada for water resources research and among top 100 globally in four subject areas

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Jul 14, 2020
By USask Research Profile and Impact and Mark Ferguson

USask also placed in the top 100 universities in the world in three other research areas: environmental science/engineering (51-75th place), veterinary sciences (51-75th), and agricultural sciences (76-100th), according to the 2020 Shanghai Ranking Consultancy’s ARWU, an influential ranking of 1,800 universities around the world based on research performance indicators such as publications, citation impact, and international collaboration.

“These results are a reflection of the outstanding research that takes place at the University of Saskatchewan as we strive to be the university the world needs,” said USask Vice-President Karen Chad.

“Particularly notable is the fact we are among global leaders in our signature areas of water and food security, as well as in fields such as environmental sciences and new materials research that involve synchrotron-based studies at our Canadian Light Source, Canada’s only synchrotron.”

Read the full article here.

New Article – Heat Pulse Probes

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Signal processing for in situ detection of effective heat pulse probe spacing radius as the basis of a self-calibrating heat pulse probe

Nicholas Kinar, John Pomeroy and Bing Si
Published July 16, 2020
Geoscientific Instrumentation, Methods and Data Systems
volume 9, issue 2, pages 293–315
DOI: https://doi.org/10.5194/gi-9-293-2020

Abstract
A sensor comprised of an electronic circuit and a hybrid single and dual heat pulse probe was constructed and tested along with a novel signal processing procedure to determine changes in the effective dual-probe spacing radius over the time of measurement. The circuit utilized a proportional–integral–derivative (PID) controller to control heat inputs into the soil medium in lieu of a variable resistor. The system was designed for onboard signal processing and implemented USB, RS-232, and SDI-12 interfaces for machine-to-machine (M2M) exchange of data, thereby enabling heat inputs to be adjusted to soil conditions and data availability shortly after the time of experiment. Signal processing was introduced to provide a simplified single-probe model to determine thermal conductivity instead of reliance on late-time logarithmic curve fitting. Homomorphic and derivative filters were used with a dual-probe model to detect changes in the effective probe spacing radius over the time of experiment to compensate for physical changes in radius as well as model and experimental error. Theoretical constraints were developed for an efficient inverse of the exponential integral on an embedded system. Application of the signal processing to experiments on sand and peat improved the estimates of soil water content and bulk density compared to methods of curve fitting nominally used for heat pulse probe experiments. Applications of the technology may be especially useful for soil and environmental conditions under which effective changes in probe spacing radius need to be detected and compensated for over the time of experiment.

Read the full article here.