Linkages between Arctic sea ice cover, large-scale atmospheric circulation, and weather and ice conditions in the Gulf of Bothnia, Baltic Sea

Abstract

During years 1980/1981–2012/2013, inter-annual variations in sea ice and snow thickness in Kemi, in the northerncoast of the Gulf of Bothnia, Baltic Sea, depended on the air temperature, snow fall, and rain. Inter-annual variations in theNovember—April mean air temperature, accumulated total precipitation, snow fall, and rain, as well as ice and snow thickness inKemi and ice concentration in the Gulf of Bothnia correlated with inter-annual variations of the Pacific Decadal Oscillation (PDO),Arctic Oscillation (AO), North Atlantic Oscillation (NAO), Scandinavian Pattern (SCA), and Polar / Eurasian Pattern (PEU). Thestrong role of PDO is a new finding. In general, the relationships with PDO were approximately equally strong as those with AO,but rain and sea ice concentration were better correlated with PDO. The correlations with PDO were, however, not persistent; fora study period since 1950 the correlations were much lower. During 1980/1981—2012/2013, also the Pacific / North AmericanPattern (PNA) and El Nino–Southern Oscillation (ENSO) had statistical connections with the conditions in the Gulf of Bothnia,revealed by analyzing their effects combined with those of PDO and AO. A reduced autumn sea ice area in the Arctic was relatedto increased rain and total precipitation in the following winter in Kemi. This correlation was significant for the Pan-Arctic sea icearea in September, October, and November, and for the November sea ice area in the Barents / Kara seas.