Abstract:

Based on the European Center of Medium Range Weather Forcast(ECMWF)reanalysis dataset(ERA40),winter climate change and characteristics of sea ice-atmosphere interaction in northern high latitudes for recent several decades are analyzed.Under the background of global warming,the amplitude of temperature increase in winter in northern high latitudes is getting bigger and it has different features in different regions.From the end of 1970s,the Greenland Sea,the Barents Sea and the most part of Euro-Asian continent and North American continent are getting warmer,whereas the Labrador Sea,the Greenland and the area around the Bering Strait are getting colder.Meanwhile,the sea level pressure in the center part of the northern polar region and the region where the climatic Icelandic low exist decreases,but in places farther southward it increases.Since the 1970s,the sensible heat flux and latent heat flux sent to the atmosphere from the Greenland Sea and the Barents Sea has increased,this is mainly due to the reduction of sea ice concentration and the weakening effect of insulator and shield of the solid ice accordingly caused by the increase of air temperature.In sea ice free area of the Norwegian Sea,the sensible heat flux and latent heat flux sent to the atmosphere has re- duced due to decrease of temperature difference between the air and the sea surface caused by increase of air temperature.In the Labrador Sea,due to decrease of air temperature and in- crease of temperature difference between the air and the sea surface accordingly,the sea gives more sensible heat flux and latent heat flux to the air.This will lead to the growth of sea ice ex- tent there.The features of linear regression of sea surface pressure,sea ice concentration and sum of sensible heat flux and latent heat flux toward time series of the leading mode of EOF ex- pansion of surface air temperature are close to those of their own EOF expansion for the leading mode respectively.