A climatology of wintertime low-level jets in Nares Strait

• Published in: Polar Research
• Main Authors: Svenja H.E. Kohnemann, Günther Heinemann
• Format: Article in Journal/Newspaper
• Language: English
• Published: Norwegian Polar Institute 2021
• Subjects: arctic; gap flow; atmospheric modelling; greenland; north water polynya; wind; envir; geo; Arctic; Ellesmere Island; Greenland; Nares; Smith Sound; Nares strait; Polar Research; Smith sound
• Online Access: https://doi.org/10.33265/polar.v40.3622; https://doaj.org/article/55b1a70d1d0e499c9e1b254e8b7b794e

Intense, southward low-level winds are common in Nares Strait, between Ellesmere Island and northern Greenland. The steep topography along Nares Strait leads to channelling effects, resulting in an along-strait flow. This research study presents a 30-year climatology of the flow regime from simulations of the COSMO-CLM climate model. The simulations are available for the winter periods (November–April) 1987/88 to 2016/17, and thus, cover a period long enough to give robust long-term characteristics of Nares Strait. The horizontal resolution of 15 km is high enough to represent the complex terrain and the meteorological conditions realistically. The 30-year climatology shows that LLJs associated with gap flows are a climatological feature of Nares Strait. The maximum of the mean 10-m wind speed is around 12 m s-1 and is located at the southern exit of Smith Sound. The wind speed is strongly related to the pressure gradient. Single events reach wind speeds of 40 m s-1 in the daily mean. The LLJs are associated with gap flows within the narrowest parts of the strait under stably stratified conditions, with the main LLJ occurring at 100–250 m height. With increasing mountain Froude number, the LLJ wind speed and height increase. The frequency of strong wind events (>20 m s-1 in the daily mean) for the 10 m wind shows a strong interannual variability with an average of 15 events per winter. Channelled winds have a strong impact on the formation of the North Water polynya.