Energy Exchange During River Icing Formation in a Subarctic Environment, Yukon Territory
Icings are common hydrologic phenomena in cold subarctic environments. They are formed by the accumulation of repeated overflow layers during winter. The size and thickness of the icing layers, however, are determined by the interaction of surface water hydrologic and microclimatologic systems. This...
| Published in: | Géographie physique et Quaternaire |
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| Main Authors: | , , |
| Format: | Text |
| Language: | French |
| Published: |
Les Presses de l'Université de Montréal
1999
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| Subjects: | |
| Online Access: | http://id.erudit.org/iderudit/004880ar https://doi.org/10.7202/004880ar |
| Summary: | Icings are common hydrologic phenomena in cold subarctic environments. They are formed by the accumulation of repeated overflow layers during winter. The size and thickness of the icing layers, however, are determined by the interaction of surface water hydrologic and microclimatologic systems. This paper examines the energy exchanges associated with icing layers with different thicknesses. In the case of thick layers of overflow, ice layers require a longer time to freeze completely due to greater latent heat stored in larger water volumes. Milder air temperatures will slow growth even further. Under such conditions, flowing water between the top ice cover and the underlying ice body provides significant amounts of energy. As much as 60-87 % of the energy may be supplied by running water. Under progressively colder temperature conditions, faster growth rates reduce the time of water flow and, therefore, reducing the relative amount of energy supplied by flowing water. In this case energy is provided mainly by the latent heat released by the freezing of water contained in the overflow layer. Under certain conditions, the absorption of solar radiation also generates a considerable amount of energy input to the regime. This energy is released mostly through sensible and radiative heat losses. During icing layer formation, latent heat is the least important, accounting for only 6-17 % of the total heat loss. La formation de nappes de glace stratifiée est un phénomène hydrologique cou- rant en milieu subarctique. Il résulte de l'accumulation d'écoulements successifs pendant l'hiver. La taille et l'épaisseur des couches de glace sont déterminées par l'interaction entre les systèmes microclimatologique et hydrologique de l'eau de surface. On étudie ici les échanges d'énergie suivant différentes épaisseurs de nappes de glace. Dans le cas d'épaisses nappes d'écoulement, les couches de glace prennent plus de temps à geler entièrement en raison de la plus grande quantité de chaleur latente emmagasinée dans les volumes ... |
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