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边界诱导的极端降水和温度气候网络偏差

Boundary-Induced Biases in Climate Networks of Extreme Precipitation and Temperature

University of Texas at Arlington(德克萨斯大学阿灵顿分校);University of Connecticut(康涅狄格大学);University of Maryland at Baltimore County(马里兰大学巴尔的摩县分校);Broad Institute of MIT and Harvard(麻省理工学院和哈佛大学的布罗德研究所);Potsdam Institute for Climate Impact Research(波茨坦气候影响研究所);Humboldt University of Berlin(柏林洪堡大学)

Behzad Ghanbarian, Victor Oladoja, Kehinde Bosikun, Tayeb Jamali, Jürgen Kurths

AI总结:

本研究评估了两种修正方法对气候网络指标的影响,发现减法和除法方法在统计上存在显著差异,揭示了极端降水和温度事件网络的季节性变化及区域遥相关性。

摘要:

为了解决气候网络中的空间边界效应,文献中广泛应用了两种基于代理的修正方法,即(1)减法和(2)除法。在减法方法中,原始网络指标通过减去从代理集合中获得的期望值得到调整,而在除法方法中,则通过除以该期望值得到归一化。然而,到目前为止,我们尚未发现任何先前研究评估这两种修正方法是否会产生统计上不同的结果。在本研究中,我们构建了覆盖北美大陆(CONUS)的极端降水和温度事件(EPEs和ETEs)复杂网络,涵盖夏季(6月至8月,JJA)和冬季(12月至2月,DJF)两个季节。我们计算了关键网络指标:度中心性(DC)、聚类系数(CC)、平均地理距离(MGD)和介数中心性(BC),并应用了这两种修正方法。尽管修正后的空间模式在视觉上相似,但统计分析显示,来自减法和除法方法的网络指标在95%置信水平下存在显著差异。在整个CONUS范围内,EPEs的网络枢纽主要集中在北美的西北部在夏季,而在冬季则向东部转移,反映了主导大气驱动因素的季节性差异。相比之下,ETE网络在两个季节中都表现出强空间一致性,并在两个季节中都表现出明显的区域遥相关性,冬季具有更高的连通性和更长的同步距离,与太平洋-北美和北大西洋振荡模式等大尺度环流模式一致。我们的结果表明,CC和MGD比DC和BC对修正方法更敏感,特别是在EPE网络中。

英文摘要:

To address spatial boundary effects in climate networks, two surrogate-based correction methods, (1) subtraction and (2) division, have been widely applied in the literature. In the subtraction method, an original network measure is adjusted by subtracting the expected value obtained from a surrogate ensemble, whereas in the division method, it is normalized by dividing by this expected value. However, to the best of our knowledge, no prior study has assessed whether these two correction approaches yield statistically different results. In this study, we constructed complex networks of extreme precipitation and temperature events (EPEs and ETEs) across the CONUS for both summer (June-August, JJA) and winter (December-February, DJF) seasons. We computed key network metrics degree centrality (DC), clustering coefficient (CC), mean geographic distance (MGD), and betweenness centrality (BC) and applied both correction methods. Although the corrected spatial patterns generally appeared visually similar, statistical analyses revealed that the network measures derived from the subtraction and division methods were significantly different at the 95 percent confidence level. Across the CONUS, network hubs of EPEs were primarily concentrated in the northwestern United States during summer and shifted toward the east during winter, reflecting seasonal differences in the dominant atmospheric drivers. In contrast, the ETE networks showed strong spatial coherence and pronounced regional teleconnections in both seasons, with higher connectivity and longer synchronization distances in winter, consistent with large-scale circulation patterns such as the Pacific-North American and North Atlantic Oscillation modes. Our results indicated that the network metrics CC and MGD were more sensitive to the correction methods than the DC and BC, particularly in the EPE networks.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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