The Southern Annular Mode (SAM) is the predominant atmospheric variability mode in the Southern Hemisphere. In this paper, we present the spatial variability results of the SAM pattern for the period 1979–2018. The SAM‐intrinsic pattern variability analysis is based on the principal component analysis (PCA), which is carried out for the ERA‐Interim 500 hPa geopotential height (GPH) data set. A spatiotemporally resolved data set of SAM pattern maps (PCA loadings) is derived by projecting monthly shifted sub‐sequences of SAM index values (PCA scores) on the corresponding GPH anomalies. The dominant SAM structure within single pattern fields is mapped automatically and can be interpreted as the Southern Hemisphere polar front. This data set allows an analysis of the geographical positions of the characteristic circumpolar SAM structure over four decades and shows considerable variability over space and time. Five different states of SAM patterns, which are associated with characteristic circulation anomalies during different phases of the study period, are identified. Station‐based Antarctic temperature anomalies can be synoptically explained by these circulation anomalies. The overall latitudinal trend of the SAM pattern indicates an intensification of the meridional structure, especially over the East Antarctic Southern Ocean. Furthermore, we show that the SAM pattern variability is significantly correlated with the Pacific Decadal Oscillation and the Atlantic Multidecadal Oscillation. Composites of 500 hPa GPH anomalies during the positive and negative phases of the respective indices indicate teleconnections with Pacific Decadal Oscillation and Atlantic Multidecadal Oscillation, and this can explain latitudinal trends of the SAM pattern.

中文翻译：

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南环状模式的时空变化及其对南极表面温度的影响

南部环形模式（SAM）是南半球主要的大气变化模式。在本文中，我们介绍了1979-2018年间SAM模式的空间变异性结果。SAM固有模式变异性分析基于主成分分析（PCA），该分析是针对ERA-Interim 500 hPa地势高度（GPH）数据集进行的。通过在相应的GPH异常上投影SAM索引值（PCA分数）的每月移位子序列，可以得出SAM模式图（PCA加载）的时空解析数据集。单模式场中的主要SAM结构会自动映射，可以解释为南半球极地锋。该数据集可以分析过去40年中特征性极地SAM结构的地理位置，并显示出随时间和空间的巨大变化。确定了SAM模式的五种不同状态，这些状态与研究期间不同阶段的特征性循环异常有关。这些环流异常可以用气象学来解释基于台站的南极温度异常。SAM模式的整体横向趋势表明子午线结构的增强，特别是在南极东部大洋上空。此外，我们表明，SAM模式的变化与太平洋年代际振荡（PDO）和大西洋多年代际振荡（AMO）显着相关。