Extreme daily precipitation events at Spitsbergen, an Arctic Island

Abstract

Daily station records and output from the MERRA atmospheric reanalysis for the period 1979 onwards are used to examine extreme daily precipitation events at Ny Ålesund and three other sites located on Spitsbergen. Spitsbergen, lying between 77 ∘ N and 80 ∘ N, is the largest island of the Svalbard Archipelago. The region is frequently influenced by extratropical cyclones associated with the North Atlantic cyclone track and (in winter) regional baroclinicity due to proximity to the sea ice margin. Despite the stronger cyclone activity in winter, extreme precipitation events at Ny Ålesund, defined as those in the top 1% of the statistical distribution, can occur year round. On the basis of a composite analysis, extreme events tend to occur when the region is influenced by a trough of low sea level pressure extending from the southwest, southerly winds in the troposphere, positive anomalies in precipitable water, and pronounced upward motion (negative omega) at 500 hPa. This is linked to positive anomalies in 500 hPa heights over the Barents Sea and negative anomalies over Greenland. While individual extreme events do not share all of these characteristics, strong southerly flow and positive anomalies in precipitable water provide a near common thread. Reflecting local topography, extremes at Ny Ålesund are typically not well represented at other stations on the island, but there are notable exceptions. Some of the largest precipitation events can be associated with features resembling 'atmospheric rivers', seen as narrow corridors of pronounced positive anomalies in precipitable water extending thousands of kilometres south into the subtropical Atlantic. There is no systematic pattern of temporal trends in the frequency or magnitude of extremes.

Springtime extreme moisture transport into the Arctic and its impact on sea ice concentration

“…A weak but significant anomalous high also appears to the east of Canada and weakly connects to the Scandinavia high. The Z500 patterns are resemble those in Serreze et al [], which are defined in terms of extreme precipitation over Svalbard only. Comparing the dominating weather regimes over the Atlantic (Figure S1) to the composite Z500 field suggests that the extreme moisture transport is most associated with Figures S1a and S1b, or the blocking and positive phase NAO regimes.…”

The Changing Impact of Snow Conditions and Refreezing on the Mass Balance of an Idealized Svalbard Glacier

“…While we incorporate expected changes in the magnitude of temperature and precipitation variability, no potential long-term changes in the frequency and distribution of weather events are accounted for. For example, an increased frequency of heavy-precipitation events in the Northern hemisphere has been suggested (Min et al, 2011), although a recent analysis of extreme precipitation events in Svalbard reveals no significant trends over the most recent decades (Serreze et al, 2015). Furthermore, we do not account for potential trends in cloud cover and relative humidity, due to a current lack of constraints of long-term trends of these variables.…”

Effects of changing permafrost and snow conditions on tundra wildlife: critical places and times

“…6). On Svalbard, rain-on-snow events of >50 mm are not uncommon in winter despite the high latitude of the site and are linked to specific weather patterns such as low sea level pressure extending from the southwest (Serreze et al 2015). The formation of ice at the soil surface following large rain-on-snow events (Hansen et al 2014) and the ensuing reduction in forage availability negatively affects all herbivores (voles, reindeer, and ptarmigans) (Hansen et al 2013).…”