Effects of ice on the hydraulics of Mackenzie River at the outlet of Great Slave Lake, N.W.T.: a case study

1995 ◽  
Vol 22 (1) ◽  
pp. 43-54 ◽  
Author(s):  
Faye Hicks ◽  
Xiaobing Chen ◽  
David Andres
Keyword(s):  
Water Surface ◽  
Open Water ◽  
Ice Cover ◽  
Late Winter ◽  
Ice Breakup ◽  
Great Slave Lake ◽  
Surface Profiles ◽  
Bed Roughness ◽  
Discharge Measurements ◽  
Mackenzie River

The effects of ice on the conveyance characteristics of the Mackenzie River at the outlet of Great Slave Lake are modeled on the basis of cross section surveys, discharge measurements, and water surface profiles taken during open water and ice covered conditions. The calibrated bed roughness values, expressed in terms of Mannings n, range from 0.020 to 0.030. Based on measured ice thicknesses ranging from 0.6 to 1.2 m in the study reach upstream of Providence Narrows, the calibrated roughness of the 1992 late winter ice cover is 0.015. Discharge estimates, based on this late winter ice cover calibration, measured water surface profiles, and documentation of major ice movements during April and May of 1992, show relatively good agreement with the discharge measurements taken at the same time. The analysis indicates that flow in the channel just downstream of Great Slave Lake is uniform under both open water and ice covered conditions. However, stage–discharge relationships at the Water Survey of Canada gauging station are affected by variable backwater conditions, particularly when an ice accumulation develops in Providence Rapids. Key words: ice, breakup, backwater curves, hydraulic resistance, river.

A conceptual model of river ice breakup

1984 ◽  
Vol 11 (3) ◽  
pp. 516-529 ◽  
Author(s):  
S. Beltaos
Keyword(s):  
Conceptual Model ◽  
Water Surface ◽  
Flow Characteristics ◽  
Ice Cover ◽  
River Ice ◽  
Meandering Channel ◽  
Transverse Cracking ◽  
Ice Breakup ◽  
Pertinent Data ◽  
Short Term Forecasting

A conceptual model of ice breakup is formulated and used to analyze and compare data from four river gauge sites. Emphasis is on the development of generalized short-term forecasting methods, which to date have been site specific. The features to be forecast are the onset and flooding potential of breakup. These are related to the water surface width available for passage of the large sheets of ice that form by transverse cracking of the ice cover. Thus it is possible to study the effects of parameters such as ice cover dimensions and channel geometry. Owing to a lack of pertinent data, other parameters such as ice mechanical properties and flow characteristics are only considered indirectly. The mechanism of transverse cracking is examined in the light of recent field observations. Bending on planes parallel to the water surface, caused by stream curvature, could account for the observed crack spacing but more data are needed for positive conclusions. The present model does not apply in cases of “overmature” breakup, proximity of stage controls, and river planforms different from the single meandering channel type. Key words: breakup, cracks, field data, forecasting, gauge records, ice, ice clearing, ice sheets, model, onset, river ice, rivers.

scholarly journals A Regional Seasonal Forecast Model of Arctic Minimum Sea Ice Extent: Reflected Solar Radiation vs. Late Winter Coastal Divergence

2021 ◽  
pp. 1
Author(s):  
Rachel Kim ◽  
Bruno Tremblay ◽  
Charles Brunette ◽  
Robert Newton
Keyword(s):  
Solar Radiation ◽  
Sea Ice ◽  
Open Water ◽  
Forecast Model ◽  
Ice Cover ◽  
The Arctic ◽  
Late Winter ◽  
Coupled Models ◽  
Sea Ice Extent ◽  
Predictive Skill

AbstractThinning sea ice cover in the Arctic is associated with larger interannual variability in the minimum Sea Ice Extent (SIE). The current generation of forced or fully coupled models, however, have difficulty predicting SIE anomalies from the long-term trend, highlighting the need to better identify the mechanisms involved in the seasonal evolution of sea ice cover. One such mechanism is Coastal Divergence (CD), a proxy for ice thickness anomalies based on late winter ice motion, quantified using Lagrangian ice tracking. CD gains predictive skill through the positive feedback of surface albedo anomalies, mirrored in Reflected Solar Radiation (RSR), during melt season. Exploring the dynamic and thermodynamic contributions to minimum SIE predictability, RSR, initial SIE (iSIE) and CD are compared as predictors using a regional seasonal sea ice forecast model for July 1, June 1 and May 1 forecast dates for all Arctic peripheral seas. The predictive skill of June RSR anomalies mainly originates from open water fraction at the surface, i.e. June iSIE and June RSR have equal predictive skill for most seas. The finding is supported by the surprising positive correlation found between June Melt Pond Fraction (MPF) and June RSR in all peripheral seas: MPF anomalies indicate presence of ice or open water that is key to creating minimum SIE anomalies. This contradicts models that show correlation between melt onset, MPF and the minimum SIE. A hindcast model shows that for a May 1 forecast, CD anomalies have better predictive skill than RSR anomalies for most peripheral seas.

Flow conveyance with ice cover for the Nashwaak River, N.B.

1982 ◽  
Vol 9 (4) ◽  
pp. 674-677
Author(s):  
B. Burrell ◽  
K. S. Davar
Keyword(s):  
Cross Sections ◽  
Water Surface ◽  
Open Water ◽  
Ice Cover ◽  
Cross Sectional Area ◽  
Water Levels ◽  
Flow Section ◽  
Sectional Area ◽  
Cross Sectional ◽  
Water Conditions

Measurements were undertaken along a 460-m long portion of the Nashwaak River, N.B., in order to study the flow conveyance characteristics of a regional watercourse during ice-cover and open-water conditions. Elevations of the water surface under both conditions were obtained at five cross sections for varying water levels and discharges. Various difficulties experienced in defining the cross-sectional area of the flow section, determining the influence of slush and anchor ice on the slope, and the roughness characteristics of the undersurface of the ice cover are described in order to provide a perspective on some commonly encountered problems.

scholarly journals Observations and Simulations of Meteorological Conditions over Arctic Thick Sea Ice in Late Winter during the Transarktika 2019 Expedition

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 174
Author(s):  
Günther Heinemann ◽  
Sascha Willmes ◽  
Lukas Schefczyk ◽  
Alexander Makshtas ◽  
Vasilii Kustov ◽  
...  
Keyword(s):  
Sea Ice ◽  
Climate Models ◽  
Climate Model ◽  
Regional Climate ◽  
Open Water ◽  
The Arctic ◽  
Late Winter ◽  
Good Representation ◽  
Hourly Temperature ◽  
Ice Model

The parameterization of ocean/sea-ice/atmosphere interaction processes is a challenge for regional climate models (RCMs) of the Arctic, particularly for wintertime conditions, when small fractions of thin ice or open water cause strong modifications of the boundary layer. Thus, the treatment of sea ice and sub-grid flux parameterizations in RCMs is of crucial importance. However, verification data sets over sea ice for wintertime conditions are rare. In the present paper, data of the ship-based experiment Transarktika 2019 during the end of the Arctic winter for thick one-year ice conditions are presented. The data are used for the verification of the regional climate model COSMO-CLM (CCLM). In addition, Moderate Resolution Imaging Spectroradiometer (MODIS) data are used for the comparison of ice surface temperature (IST) simulations of the CCLM sea ice model. CCLM is used in a forecast mode (nested in ERA5) for the Norwegian and Barents Seas with 5 km resolution and is run with different configurations of the sea ice model and sub-grid flux parameterizations. The use of a new set of parameterizations yields improved results for the comparisons with in-situ data. Comparisons with MODIS IST allow for a verification over large areas and show also a good performance of CCLM. The comparison with twice-daily radiosonde ascents during Transarktika 2019, hourly microwave water vapor measurements of first 5 km in the atmosphere and hourly temperature profiler data show a very good representation of the temperature, humidity and wind structure of the whole troposphere for CCLM.

Wintertime growth in Atlantic salmon under changing climate: the importance of ice cover for individual growth dynamics

2021 ◽  
Author(s):  
Laura Härkönen ◽  
Pauliina Louhi ◽  
Riina Huusko ◽  
Ari Huusko
Keyword(s):  
Climate Change ◽  
Atlantic Salmon ◽  
Growth Rates ◽  
Growth Dynamics ◽  
Ice Cover ◽  
Individual Growth ◽  
Late Winter ◽  
Dynamic Nature ◽  
Individual Level ◽  
Growth Variation

Understanding the dynamic nature of individual growth in stream-dwelling salmonids may help forecast consequences of climate change on northern fish populations. Here, we performed an experimental capture-mark-recapture study in Atlantic salmon to quantify factors influencing wintertime growth variation among juveniles under different scenarios for ice cover reduction. We applied multiple imputation to simulate missing size observations for unrecaptured fish, and to account for individual-level variation in growth rates. The salmon parr exhibited substantial body length shrinkage in early winter, suppressed growth through mid-winter, and increasing growth rates in late winter and particularly in spring. Unexpectedly, the presence of ice cover had no direct effects on wintertime growth. Instead, our results implied increasing energetic costs with reducing ice cover: individuals exposed to absent or shortened ice-covered period gained mass at a lowered rate in spring whereas the present, long ice-covered period was followed by rapid growth. This study emphasizes natural resilience of Atlantic salmon to wintertime environmental variation which may help the species to cope with the reductions in ice cover duration due to climate change.

Discussion of “Water Surface Profiles in Irregular Natural Streams”

1962 ◽  
Vol 88 (1) ◽  
pp. 113-117
Author(s):  
R. M. Advani ◽  
Cornelius C. S. Shih ◽  
J. Kerr
Keyword(s):  
Water Surface ◽  
Natural Streams ◽  
Surface Profiles

scholarly journals Theoretical study of ice cover phenology at large freshwater lakes based on SMOS MIRAS data

2018 ◽  
Vol 12 (8) ◽  
pp. 2727-2740 ◽  
Author(s):  
Vasiliy Tikhonov ◽  
Ilya Khvostov ◽  
Andrey Romanov ◽  
Evgeniy Sharkov
Keyword(s):  
Brightness Temperature ◽  
Open Water ◽  
Ice Cover ◽  
Freshwater Lakes ◽  
Ice Melt ◽  
Bear Lake ◽  
Ocean Salinity ◽  
Satellite Microwave ◽  
Transportation Routes ◽  
Temperature Time

Abstract. The paper presents a theoretical analysis of seasonal brightness temperature variations at a number of large freshwater lakes: Baikal, Ladoga, Great Bear Lake (GBL), Great Slave Lake (GSL), and Huron, retrieved from Microwave Imaging Radiometer with Aperture Synthesis (MIRAS) data (1.4 GHz) of the Soil Moisture and Ocean Salinity (SMOS) satellite. The analysis was performed using the model of microwave radiation of plane layered heterogeneous nonisothermal medium. The input parameters for the model were real regional climatological characteristics and glaciological parameters of ice cover of the study lakes. Three distinct seasonal brightness temperature time regions corresponding to different phenological phases of the lake surfaces: complete ice cover, ice melt and deterioration, and open water were revealed. The paper demonstrates the possibility to determine the beginning of ice cover deterioration from satellite microwave radiometry data. The obtained results can be useful for setting the operating terms of winter crossings and roads on ice, as with the beginning of ice deterioration, these transportation routes across water bodies (rivers, lakes, water reservoirs) become insecure and cannot be used any more.

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