Extreme cyclone events in the Arctic: Wintertime variability and trends
Typically 20 40 extreme cyclone events (sometimes called 'weather bombs' occur in the Arctic North Atlantic per winter season, with an increasing trend of 6 events/decade over 1979 2015, according to 6 hourly station data from Ny Alesund. This increased frequency of extreme cyclones is consistent with observed significant winter warming, indicating that the meridional heat and moisture transport they bring is a factor in rising temperatures in the region. The winter trend in extreme cyclones is dominated by a positive monthly trend of about 3 4 events/decade in November December, due mainly to an increasing persistence of extreme cyclone events. A negative trend in January opposes this, while there is no significant trend in February. We relate the regional patterns of the trend in extreme cyclones to anomalously low sea ice conditions in recent years, together with associated large scale atmospheric circulation changes such as 'blocking like' circulation patterns (e.g. Scandinavian blocking in December and Ural blocking during January February)