2000—2019年北极多年冰时空变化分析

Spatiotemporal variations of Arctic multi-year ice from 2000 to 2019

海冰是北极生态系统最重要的组成部分之一,同时也是北极气候变化的指示器。多年冰是海冰组成中最重要的部分之一,研究北极地区多年冰的时空变化能更深度地揭示极地气候的变化。本文基于美国国家冰雪数据中心(NSIDC)提供的海冰冰龄和冰厚数据,分析了2000—2019年北极多年冰范围和冰龄分布的时空变化特征以及冰厚和体积的时空变化特征。同时结合欧洲中期天气预报中心(ECMWF)提供的再分析数据,对多年冰变化开展归因分析。结果表明,研究期内北极多年冰主要分布在北极中心海域,占比65.6%。相较于2000年,2019年多年冰范围和5年及以上海冰比例呈明显缩减趋势,分别减小1.61×10^(6)km^(2)和21%,其中楚科奇海和波弗特海海域减小速率最快。2011—2019年多年冰平均厚度是2.35±0.18 m,结冰期冰厚、体积增加量的年际间波动较大,融冰期的减小速率普遍大于结冰期的增加速率。在各类环境参量的相关性分析中,2 m空气温度、海表面温度与多年冰的变化有显著的负相关关系,相关系数分别为–0.78和–0.77。在全球变暖和“北极放大效应”影响下,未来北极海冰特别是多年冰的变化需要引起更多关注。

Multi-year sea ice is a critical component of the Arctic ecosystem and can act as an indicator of Arctic climate change.For instance,the spatial and temporal variability of multi-year ice in the Arctic region can reveal broader regional climatic trends.Based on sea ice age and thickness data from the U.S.National Snow and Ice Data Center(NSIDC),this paper analyzed the temporal and spatial variation characteristics of multi-year Arctic ice extent and age from 2000 to 2019.Ice thickness and volume dynamics between 2011 to 2019 are also assessed.An attribution analysis of multi-year ice variations was then carried out based on the reanalysis data provided by the European Center for Medium-Term Weather Forecasting(ECMWF).The results showed that the majority of Arctic multi-year ice(65.6%)was mainly distributed in the central part of the Arctic.Compared with 2000,the extent of multi-year ice decreased by 1.61×10^(6) km^(2) in 2019,and the proportion of sea ice,which persists for at least five years or more,decreased by 21%.The fastest reductions occurred in the Chukchi Sea and Beaufort Sea.From 2011 to 2019,the average thickness of multi-year ice was 2.35±0.18 m.The increase of ice thickness and volume fluctuated greatly from year to year during the icing period,and the decrease rate during the melting period was generally faster than the increase rate during the icing period.Among the correlation analysis of various environmental parameters,the 2-m air temperature and sea surface temperature exhibited the strongest significant negative correlations with multi-year ice variations,with the correlation coefficients are–0.78 and–0.77,respectively.In light of continued global warming and“Arctic amplification”,more attention should be paid to the future variations of Arctic sea ice,especially multi-year ice changes with greater thickness and longer retention,which have a major impact on the Arctic ice mass balance.