Long-term variations of the seasonal snow cover in Nordland, Norway: The influence of the North Atlantic Oscillation

• Published in: Annals of Glaciology
• Main Author: Theakstone, Wilfred H.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2013
• Subjects: Arctic; Norway; Annals of Glaciology; Nordland; North Atlantic; North Atlantic oscillation
• Online Access: https://research.manchester.ac.uk/en/publications/719fd56c-65ff-4ef3-880b-d52ba1b35a6b; https://doi.org/10.3189/2013AoG62A300; http://docserver.ingentaconnect.com/deliver/connect/igsoc/02603055/v54n62/s5.pdf?expires=1376361405&id=75162596&titleid=6496&accname=Elsevier+BV&checksum=427BA1715EA306BAC685B94B7EA2FE20

Temporal and spatial variations of the seasonal snow cover at 40 sites in Nordland county, Norway, since the last decade of the 19th century are examined. Nordland lies across the Arctic Circle. Annual maximum snow depths there have varied, reflecting the interaction of synoptic conditions, temperature and terrain. North/south and coastal/inland differences are evident, but common temporal trends are identified. Maximum snow depths are strongly related to the winter North Atlantic Oscillation index. Early in the 20th century, the index was positive and the associated stormy conditions resulted in a deep, prolonged snow cover. As the index declined in the 1920s, snow depths decreased sharply. Through much of the second half of the 20th century they increased as the index tended to become more positive. The start and duration of the period of continuous snow cover is influenced by the autumn NAO index. A decrease of duration around 1990 was particularly evident at low-lying stations and those in northern Nordland. The NAO has varied considerably over the past 120 years. Because of its influence, forecasting future trends of snow depth and snow-cover duration is not a simple task.