Accelerated Springtime Melt of Snow on Tundra Downwind from Northern Alaska River Systems Resulting from Niveo-aeolian Deposition Events

• Published in: ARCTIC
• Main Authors: de Boer, Gijs, Cox, Christopher J., Creamean, Jessie M.
• Format: Article in Journal/Newspaper
• Language: English
• Published: The Arctic Institute of North America 2019
• Subjects: Deposition; albedo; North Slope of Alaska; wind; snow; melt; storm; climate; rivers; dépôt; albédo; North Slope de l’Alaska; vent; neige; fonte; tempête; climat; cours d’eau; Arctic; north slope; Tundra; Alaska
• Online Access: https://journalhosting.ucalgary.ca/index.php/arctic/article/view/68654

It is well known that light-absorbing particulate matter (PM) enhances absorption of sunlight when deposited on ice and snow. Such increased absorption is due to a reduction in surface albedo, resulting in accelerated melt of frozen surfaces. In isolation, earlier melt enhances Arctic warming since dark surfaces underlying snow and ice are exposed and absorb additional solar energy. Here, we combine various observational tools to demonstrate that aeolian deposition of PM along fluvial features on the North Slope of Alaska resulted in a notable reduction of surface albedo in the spring of 2016, from values typical for snow (~0.8) to around 0.35 on average. This reduction resulted in accelerated snow and ice melt by up to three weeks compared to unaffected areas. This phenomenon was observed to some degree in 12 other years dating back to 2003. Deposition generally was found to occur near particular sections of the rivers, with several areas affected by events in multiple years. In all years, the deposition is attributed to high wind events. The extreme case in 2016 is linked to unusually strong and extraordinarily persistent winds during April. The deposited material is thought to be the natural sediment carried by the rivers, resulting in a seasonally replenished source of PM. These findings indicate a previously unreported impact of both fluvial and atmospheric processes on the seasonal melt of northern Alaska rivers. Il s’agit d’un fait bien connu que la matière particulaire photo-absorbante rehausse l’absorption de la lumière solaire lorsqu’elle est déposée sur la glace et la neige. Cette absorption accrue est attribuable à la réduction de l’albédo de la surface, ce qui se traduit par la fonte accélérée des surfaces glacées. Individuellement, la fonte hâtive augmente le réchauffement de l’Arctique parce que les surfaces sombres se trouvant sous la neige et la glace sont exposées et absorbent l’énergie solaire supplémentaire. Ici, nous recourons à divers outils d’observation pour montrer que le dépôt éolien ...