New Article – John Pomeroy’s love of place fuels world-leading scientific work

Bryn Levy
Star Phoenix, November 19, 2020

“Maybe it sounds silly, but I really have to love a place to understand it scientifically as well.”

Growing up downwind of Lake Erie may have helped steer John Pomeroy toward a career in water science.
“I was always taught ‘never touch lake water,’ ” he says of his childhood in northern Ohio.

“The area I lived in was very polluted. The river nearby would catch fire because of the heavy oil slicks on it. Lake Erie was dying at the time and the stench of dead fish off it was awful,” Pomeroy, now 60, says from his home just outside Saskatoon.

Pomeroy currently serves as Canada research chair in water resources and climate change at the University of Saskatchewan, as well as director of the school’s Global Water Futures Programme and the University of Saskatchewan Centre for Hydrology.

Read the full article here.

New Article – Global Water Futures projects

USask-led Global Water Futures announces 12 new projects to advance water security across Canada

Mark Ferguson, and USask Research Profile and Impact
USask News

Oct 28, 2020

After four years of transformative research, the University of Saskatchewan (USask)–led Global Water Futures (GWF) program—the world’s largest university-led freshwater research program —is launching the second phase of its seven-year mission with a $2.5-million investment in 12 new critically important water security projects.

Read the article here.

Global Water Futures featured in Water News Magazine article

Global Water Futures: Solutions to Water Threats in an Era of Global Change
by Stacey Dumanski, Stephanie Merrill, Chris DeBeer, John Pomeroy

Water News
Volume 39, number 3 – Fall/Winter 2020

Canada is losing its cool.  The climate in Canada is warming twice as fast as the global average, with some areas in the north tripling that pace. Precipitation is changing too, with increases in many parts of the country and greater concentrations in floods and droughts. Climate and water are fundamentally linked in the earth system – water governs the climate and in turn climate affects water availability and timing. Together they support diverse ecosystems and aspects of water for human use: food production, manufacturing and recreation. This rapid climate warming, coupled with land use changes, has already resulted in destructive changes to the Canadian hydrology and that of cold regions around the world. Snowpacks are declining, glaciers are retreating with accelerated melt, precipitation patterns are changing, all while floods are intensifying and risk of drought and wildfires are increasing. All of these changes pose great challenges to the security of our critical infrastructure, ecosystems, and human health.



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New Article – Freeze-Thaw Changes on the Tibetan Plateau

Freeze–Thaw Changes of Seasonally Frozen Ground on the Tibetan Plateau from 1960 to 2014

Siqiong Luo; Jingyuan Wang; John W. Pomeroy; Shihua Lyu

American Meteorological Society Journal of Climate,
Volume 33, Issue 2, pages 9427–9446.
October 2, 2020

The freeze–thaw changes of seasonally frozen ground (SFG) are an important indicator of climate change. Based on observed daily freeze depth of SFG from meteorological stations on the Tibetan Plateau (TP) from 1960 to 2014, the spatial–temporal characteristics and trends in SFG were analyzed, and the relationships between them and climatic and geographical factors were explored. Freeze–thaw changes of SFG on a regional scale were assessed by multiple regression functions. Results showed multiyear mean maximum freeze depth, freeze–thaw duration, freeze start date, and thaw end date that demonstrate obvious distribution characteristics of climatic zones. A decreasing trend in maximum freeze depth and freeze–thaw duration occurred on the TP from 1960 to 2014. The freeze start date has been later, and the thaw end date has been significantly earlier. The freeze–thaw changes of SFG significantly affected by soil hydrothermal conditions on the TP could be assessed by elevation and latitude or by air temperature and precipitation, due to their high correlations. The regional average of maximum freeze depth and freeze–thaw duration caused by climatic and geographical factors were larger than those averaged using meteorological station data because most stations are located at lower altitudes. Maximum freeze depth and freeze–thaw duration have decreased sharply since 2000 on the entire TP. Warming and wetting conditions of the soil resulted in a significant decrease in maximum freeze depth and freeze–thaw duration in the most area of the TP, while drying soil results in a slight increase of them in the southeast of the TP.

Read the full article here.

New Article – Canada Water Agency

Canada Water Agency will help protect and sustain Canada’s water resources, say USask water scientists

USask News
September 29, 2020

The new Canada Water Agency—announced in the recent federal Throne Speech—is the first critical step toward transforming how water is managed across the country, said John Pomeroy, director of the University of Saskatchewan (USask)-led Global Water Futures (GWF) program.

Read the article here.

New Article- Snow Modelling Issues

Scientific and human errors in a snow model intercomparison

Cecile B. Menard; Richard Essery; Gerhard Krinner; Gabriele Arduini; Paul Bartlett; Aaron Boone; Claire Brutel-Vuilmet; Eleanor Burke; Matthias Cuntz; Yongjiu Dai Bertrand Decharme; Emanuel Dutra; Xing Fang; Charles Fierz; Yeugeniy Gusev; Stefan Hagemann; Vanessa Haverd; Hyungjun Kim; Matthieu Lafaysse; Thomas Marke; Olga Nasonova; Tomoko Nitta; Masashi Niwano; John Pomeroy; Gerd Schädler; Vladimir Semenov; Tatiana Smirnova; Ulrich Strasser; Sean Swenson; Dmitry Turkov; Nander Wever; Hua Yuan

Bulletin of the American Meteorological Society 1-46
September 9, 2020

Twenty-seven models participated in the Earth System Model – Snow Model Intercomparison Project (ESM-SnowMIP), the most data-rich MIP dedicated to snow modelling. Our findings do not support the hypothesis advanced by previous snow MIPs: evaluating models against more variables, and providing evaluation datasets extended temporally and spatially does not facilitate identification of key new processes requiring improvement to model snow mass and energy budgets, even at point scales. In fact, the same modelling issues identified by previous snow MIPs arose: albedo is a major source of uncertainty, surface exchange parametrizations are problematic and individual model performance is inconsistent. This lack of progress is attributed partly to the large number of human errors that led to anomalous model behaviour and to numerous resubmissions. It is unclear how widespread such errors are in our field and others; dedicated time and resources will be needed to tackle this issue to prevent highly sophisticated models and their research outputs from being vulnerable because of avoidable human mistakes. The design of and the data available to successive snow MIPs were also questioned. Evaluation of models against bulk snow properties was found to be sufficient for some but inappropriate for more complex snow models whose skills at simulating internal snow properties remained untested. Discussions between the authors of this paper on the purpose of MIPs revealed varied, and sometimes contradictory, motivations behind their participation. These findings started a collaborative effort to adapt future snow MIPs to respond to the diverse needs of the community.

Read the full article here.



New Article- Water flow through snow water resources research

Simulation of Preferential Flow in Snow With a 2‐D Non‐Equilibrium Richards Model and Evaluation Against Laboratory Data

Nicolas R. Leroux, Christopher B. Marsh, John W. Pomeroy
Published August 10, 2020
Water Resources Research, Volume 56. Issue 9, Pages 1-11


Recent studies of water flow through dry porous media have shown progress in simulating preferential flow propagation. However, current methods applied to snowpacks have neglected the dynamic nature of the capillary pressure, such as conditions for capillary pressure overshoot, resulting in a rather limited representation of the water flow patterns through snowpacks observed in laboratory and field experiments. Indeed, previous snowmelt models using a water entry pressure to simulate preferential flow paths do not work for natural snowpack conditions where snow densities are less than 380 kg m−3. Because preferential flow in snowpacks greatly alters the flow velocity and the timing of delivery of meltwater to the base of a snowpack early in the melt season, a better understanding of this process would aid hydrological predictions. This study presents a 2‐D water flow through snow model that solves the non‐equilibrium Richards equation. This model, coupled with random perturbations of snow properties, can represent realistic preferential flow patterns. Using 1‐D laboratory data, two model parameters were linked to snow properties and model boundary conditions. Parameterizations of these model parameters were evaluated against 2‐D snowpack observations from a laboratory experiment, and the resulting model sensitivity to varying inputs and boundary conditions was calculated. The model advances both the physical understanding of and ability to simulate water flow through snowpacks and can be used in the future to parameterize 1‐D snowmelt models to incorporate flow variations due to preferential flow path formation.

Read the full article here.


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.

New Article – Heat Pulse Probes

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

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.

John Pomeroy discusses the Saskatchewan irrigation plan in CBC article

Sask.’s $4B irrigation plan must address changing climate, Indigenous rights: professor

CBC News, July 5th, 2020

“The Saskatchewan government has announced a $4-billion plan to expand irrigation out of the Lake Diefenbaker reservoir. Work is set to begin immediately, and will be completed in three phases over the next decade.

CBC reporter Jason Warick spoke Friday with John Pomeroy, a Canada Research chair and director of the University of Saskatchewan’s Global Water Futures program.”

Click here to read the full article.