STATISTICAL RELATIONSHIP BETWEEN THE NORTHERN HEMISPHERE SEA ICE AND ATMOSPHERIC CIRCULATION DURING WINTERTIME

The wintertime relationship between the Northern Hemisphere sea-ice concentration, 500-hPa height, sea level pressure and 1000-500-hPa thickness is examined. The Northern Hemispheric sea ice extent exhibits a strong sensitivity to the climatic variation of atmospheric circulation anomalies. The sea-ice extent has reduced in the Barents Sea, Greenland Sea and Labrador Sea since 1990. Particularly, the reduction of sea ice extent in the Barents Sea and Greenland Sea became evident as early as 1968. The Northern Hemispheric sea ice extent also exhibits a strong signal of decadal variability except the Greenland Sea where the downward trend is more pronounced. The sea ice variability is characterized by a dipole pattern in both the Atlantic and Pacific sectors. Its temporal variability is strongly coupled to the North Atlantic Oscillation (North Pacific Oscillation) in the Atlantic (Pacific) sector. The relationship is strongest when the atmosphere leads the sea ice by 1-2 weeks.