摘要:本文研究了1934～2018年期间太平洋年代际振荡（Interdecadal Pacific Oscillation，IPO）、大西洋年代际振荡（Atlantic Multidecadal Oscillation，AMO）以及全球变暖（Global Warming，GW）对北美地区陆地降水年代际变化的相对贡献。首先通过对冬（12至次年2月）、夏季（6～8月）北美地区的陆地降水与中低纬地区的海表面温度进行奇异值分解分析，得到对北美陆地冬季降水相对贡献较大的主要海温模态为IPO（42.33%）和AMO（23.21%），夏季则为AMO（32.66%）和IPO（21.60%）。其次利用线性回归模型，分析三种信号分别对北美冬、夏季陆地降水的相对贡献及对北美陆地不同区域降水的相对重要性，结果表明AMO对夏季北美陆地降水变化的贡献最大，IPO次之，冬季则相反，GW对冬夏季北美陆地降水都有一定的贡献。夏季期间阿拉斯加地区AMO的贡献最大，约占65.8%，加拿大地区GW的贡献最大，约占44.5%，美国本土及墨西哥地区三者贡献基本一致；冬季期间阿拉斯加和加拿大地区GW的贡献最大，分别为62.3%和44.7%，美国本土和墨西哥地区IPO的贡献最大，分别为47.9%和71.5%。进一步利用信息流方法，验证了IPO、AMO、GW对降水的敏感性区域。最后运用全球大气环流模式ECHAM 4.6进一步确定了太平洋和大西洋海温异常对北美地区陆地降水变化的影响途径，结果表明印度洋海表面温度异常在AMO和IPO对北美陆地降水变化的作用中至关重要。
关键词:北美降水/
太平洋年代际振荡（IPO）/
大西洋年代际振荡（AMO）/
全球变暖/
相对贡献
Abstract:This study investigates the relative contributions of the interdecadal Pacific oscillation (IPO), Atlantic multidecadal oscillation (AMO), and global warming (GW) to the decadal variation of land precipitation in North America from 1934 to 2018. The singular value decomposition (SVD) analysis for the North American land precipitation and sea surface temperature (SST) in the middle and low latitudes reveal that the main SST modes affecting the interdecadal variation of land precipitation are the IPO and AMO, with values of 42.33% and 23.21% in winter and 21.60% and 32.66% in summer, respectively. A linear regression model is then used to analyze the relative contribution of the three signals (IPO, AMO, and GW). For North America, results show that the AMO contributes dominantly, while IPO only plays a secondary role to IPO in summer. However, the opposite behavior is observed in winter. GW is also found to play an important role. In summer, AMO is the primary contributor to the changes in precipitation in Alaska, whereas GW dominates in Canada. Meanwhile, GW, AMO, and IPO are of equal importance in the USA and Mexico. In winter, GW is the primary contributor to the changes in precipitation in Alaska and Canada, whereas IPO dominates in the USA and Mexico. In terms of information flow, this study presents the regions of sensitivity to the three modes. Results are verified using the ECHAM 4.6 model, showing that the Indian Ocean is pivotal in having the AMO and IPO in effect, causing the precipitation variabilities.
Key words:North American precipitation/
Interdecadal Pacific oscillation (IPO)/
Atlantic multidecadal oscillation (AMO)/
global warming (GW)/
Relative contribution
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