过去2000年北极地区气候变化特征及其对AMO的响应

CLIMATE VARIABILITY IN THE ARCTIC REGION OVER THE COMMON ERA AND ITS RESPONSE TO AMO

北极地区对全球变暖十分敏感,分析北极地区过去2000年历史气候对揭示全球气候变化极其重要,也是国际过去全球变化计划(Past Global Changes,简称PAGES)的重要目标。然而,过去2000年北极不同区域的气候随时间变化是否存在一致性仍有待检验。文章基于北极地区及其3个子扇区(北大西洋扇区、阿拉斯加扇区和西伯利亚扇区)的温度序列,对过去2000年北极的气候变化进行了趋势分析与频谱特征分析,初步探讨了大西洋多年代涛动(Atlantic Multi-decadal Oscillation,简称AMO)作为驱动因子对北极地区温度的影响。结果表明,公元1~1800年间北极地区存在着普遍的降温过程(-0.47℃/ka),但温度变化区域差异显著,其中北大西洋扇区与北极地区整体温度间呈现显著的相关性(0.82)。北大西洋扇区温度呈现"平稳-下降-陡升"的趋势,阿拉斯加扇区温度呈现"下降-缓升-下降-陡升"的趋势,西伯利亚扇区温度呈现"平稳波动-陡升"的趋势。在过去200年间北极地区及其3个子扇区气候均出现了快速变暖。频谱分析表明,北极地区温度存在着准14年、准26年、准62年、准75年和准186年周期,其中北极地区温度的LFV谱在准62年与准75年周期和AMO周期大致吻合。综合交叉谱与小波分析的结果,公元1100年后,AMO以准74年的周期影响北极的气候变化,其中,北大西洋扇区受影响最为明显。阿拉斯加扇区与西伯利亚扇区虽然存在着显著的年代际周期特征,但可能与AMO的关联并不显著,这些区域气候变化的影响机理需要进一步深入研究。

Arctic region is sensitive to global warming,therefore,understanding the historical climate of Arctic region over the Common Era is very important to reveal the mechanism of climate change in Arctic region.However,the temporal consistency of climate in different regions of Arctic during the past 2000 years remains to be tested.Based on four regionally averaged temperature records in Arctic,North Atlantic,Alaska and Siberia,Arctic climate variability for the last 2 millennia has been investigated using Mann-Kendall trend analysis,MTM-SVD and spectral analysis.Then the effect of Atlantic Multi-decadal Oscillation(AMO)on Arctic temperature is discussed.Results shows that there was a general cooling process(-0.47℃/ka)in the Arctic from 1 A.D.to 1800 A.D.,but the regional difference of temperature was significant.The temperature correlation between North Atlantic region and Arctic reached 0.82.The temperature in North Atlantic region showed a trend of‘stable-decline-steep rise’,the temperature in Alaska region showed a trend of‘decline-slow rise-decline-steep rise’,and the temperature in Siberia showed a trend of‘stable-steep rise’.Temperature in the Arctic and subarctic areas has experienced rapid warming during the past 200 years.LFV spectrum analysis that there are quasi-14 years,quasi-26 years,quasi-62 years,quasi-75 years and quasi-186 years cycles in the Arctic region.The LFV spectrum of Arctic temperature is roughly consistent with AMO period in quasi-62 and quasi-75 years.Based on the Cross-spectral Analysis and Wavelet Analysis results,the temperature trend in the Arctic region affected by AMO is mainly concentrated in the North Atlantic region.There is a quasi-74-year cycle between AMO and temperature in the North Atlantic,but this cycle only occurs after 1100 A.D.Although there are significant inter-decadal periodic characteristics between Alaska and Siberia,the association with AMO may not be significant.The influence mechanism of these regional climate changes needs further study.