A comprehensive public-domain river ice process model and its application to a complex natural river

Blackburn, Julia; She, Yuntong

doi:10.1016/j.coldregions.2019.04.010

Cited by 39 publications

(17 citation statements)

References 19 publications

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“…Secondly, the estimates of the anchor ice to water heat flux could be utilized to improve the method for computing it that would use the same equation used to predict the heat flux between the ice cover and the water. Finally, it is worth noting that recent progress improving and validating river ice process models by comparison to field data has been reported in the literature (Blackburn and She, 2019;Pan et al, 2020;Wazney et al, 2019).…”

Section: Discussionmentioning

confidence: 97%

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Continuous in situ measurements of anchor ice formation, growth, and release

Ghobrial

Loewen

2021

The Cryosphere

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Abstract. In northern rivers, turbulent water becomes supercooled (i.e. cooled to slightly below the freezing point) when exposed to freezing air temperatures. In supercooled turbulent water, frazil (small ice disks) crystals are generated in the water column, and anchor ice starts to form on the bed. Two anchor ice formation mechanisms have been reported in the literature: either by the accumulation of suspended frazil particles, which are adhesive (sticky) in nature, on the riverbed or by in situ growth of ice crystals on the bed material. Once anchor ice has formed on the bed, the accumulation typically continues to grow (due to either further frazil accumulation and/or crystal growth) until release occurs due to mechanical (shear force by the flow or buoyancy of the accumulation) or thermal (warming of the water column which weakens the ice-substrate bond) forcing or a combination of the two. There have been a number of detailed laboratory studies of anchor ice reported in the literature, but very few field measurements of anchor ice processes have been reported. These measurements have relied on either sampling anchor ice accumulations from the riverbed or qualitatively describing the observed formation and release. In this study, a custom-built imaging system (camera and lighting) was developed to capture high-resolution digital images of anchor ice formation and release on the riverbed. A total of six anchor ice events were successfully captured in the time-lapse images, and for the first time, the different initiation, growth, and release mechanisms were measured in the field. Four stages of the anchor ice cycle were identified: Stage 1: initiation by in situ crystal growth; Stage 2: transitional phase; Stage 3: linear growth; and Stage 4: release phase. Anchor ice initiation due to in situ growth was observed in three events, and in the remainder, the accumulation appeared to be initiated by frazil deposition. The Stage 1 growth rates ranged from 1.3 to 2.0 cm/h, and the Stage 2 and 3 growth rates varied from 0.3 to 0.9 cm/h. Anchor ice was observed releasing from the bed in three modes: lifting of the entire accumulation, shearing of layers of the accumulation, and rapid release of the entire accumulation.

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Section: Discussionmentioning

confidence: 97%

“…These models have mostly relied on empirical or semi-empirical relations (e.g. Shen, 2010;Lindenschmidt, 2017;Blackburn and She, 2019;Makkonen and Tikanmäki, 2018), but the development of physically based models has been challenging due to the lack of accurate field measurements of anchor ice formation, growth, and release.…”

Section: Introductionmentioning

confidence: 99%

Continuous in situ measurements of anchor ice formation, growth, and release

Ghobrial

Loewen

2021

The Cryosphere

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“…Secondly, the estimates of the anchor ice to water heat flux could be used to improve the method used to compute it that uses the same equation used to predict the heat flux between the ice cover and the water. Finally, it is worth noting that recent progress improving and validating river ice process models by comparison to field data has been reported in the literature (Blackburn and She, 2019;Pan et al, 2020;Wazney et al, 2019). https://doi.org/10.5194/tc-2020-161 Preprint.…”

Section: Discussionmentioning

confidence: 99%

Continuous in situ measurements of anchor ice formation, growth and release

Ghobrial¹,

Loewen²

2020

Preprint

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Abstract. In northern rivers, turbulent water becomes supercooled (i.e. cooled to slightly below 0 °C) when exposed to freezing air temperatures. In supercooled water, frazil (small ice disks) crystals are generated in the water column and anchor ice starts to form on the bed. Two anchor ice formation mechanisms have been reported in the literature: either by the accumulation of suspended frazil particles, which are adhesive (sticky) in nature, on the river bed; or by in situ growth of ice crystals on the bed material. Once anchor ice has formed on the bed, the accumulation typically continues to grow (either due to further frazil accumulation and/or crystal growth) until release occurs due to mechanical (shear force by the flow or buoyancy of the accumulation) or thermal (warming of the water column which weakens the ice-substrate bond) forcing or a combination of the two. Although detailed laboratory experiments have been reported to study anchor ice, but very few field measurements of anchor ice processes have been reported. These measurements have relied on either sampling anchor ice accumulations from the river bed, or qualitatively describing the observed formation and release. In this study, a custom-built imaging system (camera and lighting) was developed to capture high-resolution digital images of anchor ice formation and release on the river bed. A total of six anchor ice events were successfully captured in the time-lapse images and for the first time, the different initiation, growth and release mechanisms were measured in the field. Four stages of the anchor ice cycle were identified, namely: Stage 1: initiation by in situ crystal growth, Stage 2: transitional phase, Stage 3: linear growth, and Stage 4: release phase. Anchor ice initiation due to in situ growth was observed in three events and in the remainder the accumulation appeared to be initiated by frazil deposition. The Stage 1 growth rates ranged from 1.3 to 2.0 cm/hr and the Stage 2 and 3 growth rates varied from 0.3 to 0.9 cm/hr. Anchor ice was observed releasing from the bed in three modes referred to as lifting, shearing and rapid.

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Section: Introductionmentioning

confidence: 99%

“…A number of numerical river ice models currently exist (Blackburn & She, 2019; Lindenschmidt, 2017; Shen, 2005) and must predict when supercooling will occur as part of the river ice formation process. Often, the heat flux at the air–water interface is modelled using a linear heat transfer equation, wherein one or more site‐specific heat transfer coefficients are applied in a function of air and water temperatures, and sometimes net solar radiation (Andrishak & Hicks, 2008; Blackburn & She, 2019; Lindenschmidt, 2017). While equations of this form can be quite useful when properly calibrated, it is likely that greater accuracy can be obtained if more of the heat fluxes at the water surface are properly measured or otherwise approximated in order to calculate the full heat budget.…”

Section: Introductionmentioning

confidence: 99%

A detailed energy budget analysis of river supercooling and the importance of accurately quantifying net radiation to predict ice formation

McFarlane

Clark

2021

Hydrological Processes

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River supercooling and ice formation is a regular occurrence throughout the winter in northern countries. The resulting frazil ice production can obstruct the flow through intakes along the river, causing major problems for hydropower and water treatment facilities, among others. Therefore, river ice modellers attempt to calculate the river energy budget and predict when supercooling will occur in order to anticipate and mitigate the effects of potential intake blockages. Despite this, very few energy budget studies have taken place during freeze-up, and none have specifically analysed individual supercooling events. To improve our understanding of the freeze-up energy budget detailed measurements of air temperature, relative humidity, barometric pressure, wind speed and direction, short-and longwave radiation, and water temperature were made on the Dauphin River in Manitoba. During the river freeze-up period of late October to early November 2019, a total of six supercooling events were recorded. Analysis of the energy budget throughout the supercooling period revealed that the most significant heat source was net shortwave radiation, reaching up to 298 W/m 2 , while the most significant heat loss was net longwave radiation, accounting for losses of up to 135 W/m 2. Longwave radiation was also the most significant heat flux overall during the individual supercooling events, accounting for up to 84% of the total heat flux irrespective of flux direction, highlighting the importance of properly quantifying this flux during energy budget calculations. Five different sensible (Q h) and latent (Q e) heat flux calculations were also compared, using the bulk aerodynamic method as the baseline. It was found that the Priestley and Taylor method most-closely matched the bulk aerodynamic method on a daily timescale with an average offset of 8.5 W/m 2 for Q h and 10.1 W/m 2 for Q e , while a Daltontype equation provided by Webb and Zhang was the most similar on a sub-daily timescale with average offsets of 20.0 and 14.7 W/m 2 for Q h and Q e , respectively.

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A comprehensive public-domain river ice process model and its application to a complex natural river

Cited by 39 publications

References 19 publications

Continuous in situ measurements of anchor ice formation, growth, and release

Continuous in situ measurements of anchor ice formation, growth, and release

Continuous in situ measurements of anchor ice formation, growth and release

A detailed energy budget analysis of river supercooling and the importance of accurately quantifying net radiation to predict ice formation

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