Seasonal Antarctic pressure variability during the twentieth century from spatially complete reconstructions and CAM5 simulations
Seasonal Antarctic pressure variability during the twentieth century from spatially complete reconstructions and CAM5 simulations
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DOI：
10.1007/s00382-019-04674-8
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发表时间：
2019-08-01
期刊：
影响因子：
4.6
通讯作者：
Garberoglio, Michael J.
中科院分区：
文献类型：
--
作者：
Fogt, Ryan L.;Schneider, David P.;Garberoglio, Michael J.
由于南极洲的大多数长期观测始于1950年代，因此了解整个二十世纪南极洲的气候变化仍然是一项挑战。为了解决这个问题，非夏季的多年代际变化的压力重建向极地的60度S的评估和评估与气候模式模拟整个二十世纪和二十一世纪初，以了解历史上的大气环流变化在南极洲。南方的秋季和冬季显示出大致相似的模式，20世纪初（1905-1934）为负异常，20世纪中期（1950-1980）为正压异常，最近时期（1984-2013）为负压异常，与SAM指数的同期趋势一致。在秋季，异常是显着的跨南极大陆的年际变化和重建的不确定性估计的背景下，重建的模式与模型生成的模式时，模拟包括热带海面温度和外部辐射强迫的强迫响应最好的同意。在冬季和春季，重建的异常是不太重要的，是一致的内部大气变率单独。由于热带遥相关最强区域的重建技术较低，内部大气变率较大，以及SST型本身的不确定性，因此很难评估热带SST变率对这些季节气压趋势的具体作用。无论是通过海冰重建、代用记录，还是通过改进的模式和数据同化方案，对压力变率的间接估计都将有助于进一步限制内部变率相对于SST趋势和外部辐射强迫的强迫响应的幅度。
As most permanent observations in Antarctica started in the 1950s, understanding Antarctic climate variations throughout the twentieth century remains a challenge. To address this issue, the non-summer multi-decadal variability in pressure reconstructions poleward of 60 degrees S is evaluated and assessed in conjunction with climate model simulations throughout the twentieth and early twenty-first centuries to understand historical atmospheric circulation variability over Antarctica. Austral autumn and winter seasons show broadly similar patterns, with negative anomalies in the early twentieth century (1905-1934), positive pressure anomalies in the middle twentieth century (1950-1980), and negative pressure anomalies in the most recent period (1984-2013), consistent with concurrent trends in the SAM index. In autumn, the anomalies are significant in the context of estimates of interannual variability and reconstruction uncertainty across most of the Antarctic continent, and the reconstructed patterns agree best with model-generated patterns when the simulation includes the forced response to tropical sea surface temperatures and external radiative forcing. In winter and spring, the reconstructed anomalies are less significant and are consistent with internal atmospheric variability alone. The specific role of tropical SST variability on pressure trends in these seasons is difficult to assess due to low reconstruction skill in the region of strongest tropical teleconnections, the large internal atmospheric variability, and uncertainty in the SST patterns themselves. Indirect estimates of pressure variability, whether through sea ice reconstructions, proxy records, or improved models and data assimilation schemes, will help to further constrain the magnitude of internal variability relative to the forced responses expected from SST trends and external radiative forcing.