北极海冰的气候变化与20世纪90年代的突变

应用英国Had ley气候研究中心1968~2000年的1°×1°的北半球逐月海冰密集度资料,使用EOF分解等统计方法,探讨北极海冰的气候变化趋势、海冰的突变、海冰的季节持续性和各季的特色。结果表明:(1)自1968年以来,北极海冰的减小是北半球海冰变化的总趋势;海冰的趋势变化在海冰的年际总变化中占有相当重要的地位,可达50%左右。冬春季主要减少区域在格陵兰海、巴伦支海和白令海;夏秋季海冰减少是唯一趋势,中心在北冰洋边缘的喀拉海、拉普捷夫海、东西伯利亚海、楚科奇海、波弗特海。(2)20世纪80年代中后期北极海冰已出现减小趋势,在20世纪90年代,海冰又出现范围和面积的突然减少,中心在格陵兰海和巴伦支海;即海冰减少是加速的,其变化程度已远远超过一般的自然变化。(3)海冰有很好的季节持续性,有很强的隔季相关,也有较好的隔年相关;各季节海冰分布型之间有很好的联系,表现为海冰分布型的总体变化趋势是一致的,在海冰的减少中也体现了分布型的特征。

The Decrease of the Arctic Sea Ice and the Abrupt Changes of Sea Ice in 1990s

Based on the Hadlley Centre Arctic sea-ice data for the period 1968~2000,it is found that the decrease tendency of the Arctic sea-ice in the North Hemisphere is very obvious.Since 1968,the sea-ice extent decrease was appeared in the Barents Sea,Greenland Sea and Bering Sea during winter,and the kola Sea and East Siberia Sea during summer.During 1990s the decrease was suddenly appeared in all areas of the Arctic Ocean,i.e.abrupt change,especially in the Barents Sea and Greenland Sea.The sea ice change over the Arctic Ocean is larger than the normal nature variation.The sea-ice seasonal patterns have the seasonal persistence and high relationship with the pattern before 1~4 seasons.Therefore the Sea-ice decrease tendency should maintain long time during the recent period.