Summary
The net radiation flux is a large component of the snowpack energy balance and as such is an important consideration in snowmelt studies. Physical features of a forest canopy greatly affect the supply of radiant energy to the snowpack. While a number of studies of the snowpack radiation balance in closed crown boreal forests are available, little attention has been paid to the unique subarctic open woodlands. In this study components of the radiation budget were measured over melting snowpacks at treeless and woodland sites in the Canadian subarctic. It was found that the woodland canopy reduces incoming solar flux by about 22% but increases the downward long wave flux by approximately 37%. Daytime radiation budgets are presented for sunny and cloudy days. In general the results represents a contrast to previous forest snow radiation balance studies.
Zusammenfassung
Die Strahlungsbilanz ist ein bedeutender Anteil der Wärmebilanz der Schneedecke und muß daher bei Untersuchungen der Schneeschmelze berücksichtigt werden. Der Aufbau eines Waldbestandes beeinflußt den Strahlungsfluß zur Schneedecke stark. Während eine Reihe von Untersuchungen über die Strahlungsbilanz der Schneedecke in geschlossenen borealen Wäldern zur Verfügung stehen, blieben die einmaligen, offenen subarktischen Kriechholzzonen wenig beachtet.
In dieser Untersuchung wurden die Komponenten der Strahlungsbilanz über schmelzenden Schneedecken sowohl an offenen wie an Kriechholzstandorten der kanadischen Subarktis gemessen. Es stellte sich heraus, daß der Kriechholzbestand die einfallende Sonnenstrahlung um etwa 22% reduziert, den nach unten gerichteten langwelligen Strahlungsfluß jedoch ungefähr um 37% erhöht. Es werden Strahlungsbilanzen für die Tages-stunden unter klaren und bewölkten Verhältnissen vorgestellt. Die Ergebnisse stellen einen Gegensatz zu früheren Untersuchungen der Strahlungsbilanz der Schneedecke in Wäldern dar.
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Lafleur, P., Adams, P. The effect of subarctic woodland vegetation on the radiation balance of a melting snow cover. Arch. Met. Geoph. Biocl. A. 34, 297–310 (1986). https://doi.org/10.1007/BF02257764
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DOI: https://doi.org/10.1007/BF02257764