Decadal regime shift of Arctic seasonally melting sea ice and associated decadal variability of Chinese Freezing Rain

Abstract:

Based on the HadISST sea ice concentration data from 1961-2013, we define the Arctic sea ice seasonal melting index (the average Arctic sea ice concentration for February and March which have the largest Arctic sea ice area of the year minus the average Arctic sea ice concentration for August and September which have the smallest Arctic sea ice area) and analyze the spatial and temporal characteristics of Arctic sea ice seasonal melting extent. It turns out that in recent decades there are two significant decadal regime shift, late 1970s and the middle of 1990s respectively. Before the late 1970s, the oscillation of Arctic sea ice extent was decrease under the background of global warming, the seasonal melting extent was small but increased significantly; during the late 1970s and the middle of 1990s, the oscillation of the seasonal melting extent was maintain and had no significant trend; while after the middle of 1990s, although there is a hiatus of the global warming, the melting of Arctic sea ice is accelerating, especially after 2007, during which Arctic sea ice seasonal melting extent is greatly increased. Besides that, as the time goes by, the significant seasonal melting area expanded anticlockwise from the East Siberia sea which is in north shore of Asian Arctic to Beaufort Sea-north Canadian Arctic Archipelago gradually, and expand to the central Arctic at the same time. Correspondingly, the total frequency of Chinese Freezing Rain is decreasing during the past several decades and also has significant decadal regime shift. The inter-annual amplitude of the total frequency of Chinese Freezing Rain was large during 1962-1979, then turned small during 1980-1996. After 1997 the total frequency of Chinese Freezing Rain is at a low stage, but is increasing. The relationship between sea surface temperature or sea ice concentration and Chinese Freezing Rain is also been discussed, the related key area are different during different decadal. Chinese freezing rain is influenced by sea surface temperature and sea ice through atmosphere circulation. There is a consistency between the change of Chinese Freezing Rain and the sea ice, which means that the decadal regime shift of the Arctic sea ice may be the cause of the decadal regime shift of Chinese Freezing Rain.