ARCTIC The Radiation Budget of a Subarctic Woodland Canopy
ABSTRACT. Open woodland is a major sub-type of the circum global boreal forest zone. In Canada it dominates the basins of a number of large hydroelectric schemes in which snowmelt is a critical phase of the hydrologic ycle. The forest vegetation strongly influences the radiant energy flux to the sno...
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| Format: | Text |
| Language: | English |
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1985
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.544.2279 http://pubs.aina.ucalgary.ca/arctic/arctic39-2-172.pdf |
| Summary: | ABSTRACT. Open woodland is a major sub-type of the circum global boreal forest zone. In Canada it dominates the basins of a number of large hydroelectric schemes in which snowmelt is a critical phase of the hydrologic ycle. The forest vegetation strongly influences the radiant energy flux to the snow and is therefore important in the production of snowmelt runoff and its prediction. The radiation budget of a subarctic open woodland canopy in northern Quebec is computed from measurements of net allwave, solar and longwave radiation components over the snowpack at treeless and woodland sites. The canopy gains solar radiation both directly and from solar radiation reflected off the snowpack, the latter enhanced by the larger spacing between tree crowns. Canopy heating from absorbed solar radiation leads to a considerable longwave flux being emitted by the tree crowns. Overall, the radiant energy exchange in the open woodland behaves differently than for a closed crown forest. This is believed to be a function of a variety of canopy characteristics, not solely of tree crown density. Key words: snowmelt, open woodland, radiation budget, northern Quebec & S u d. La forêt claire forme autour du monde un des sous-types importants de la zone de forêt borbale. Elle domine au Canada les bassins de quelques grands projets hyddlectriques dans lesquels la fonte des neiges comporte un des stades critiques du cycle hydrologique. La vbgetation forestibre influence de façon importante le flux d’bnergie de la neige et joue donc un rôle capital dans I’bcoulement de l’eau de fonte et dans sa prédiction. Le taux de rayonnement du couvert forestier subarctique dans le nord du Qubbec est calcul6 d’aprks des mesures des composantes du rayonnement total, solaire et de grande longueur d’onde de la neige à des sites boisbs et non boisbs. Les cimes reçoivent un rayonnement solaire en direct et aussi par dilection du manteau nival, augment6 par un plus grand espacement entre les couronnnes des arbres. Le réchauffement du couvert par ... |
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