Signatures of naturally induced variability in the atmosphere using multiple reanalysis datasets
Signatures of naturally induced variability in the atmosphere using multiple reanalysis datasets
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DOI：
10.1002/qj.2492
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发表时间：
2015-04
影响因子：
8.9
通讯作者：
D. Mitchell;L. Gray;M. Fujiwara;T. Hibino;J. Anstey;W. Ebisuzaki;Y. Harada;C. Long;S. Misios;P. Stott;D. Tan
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作者：
D. Mitchell;L. Gray;M. Fujiwara;T. Hibino;J. Anstey;W. Ebisuzaki;Y. Harada;C. Long;S. Misios;P. Stott;D. Tan
对9个不同的再分析数据集进行了多元线性回归分析，以测试与火山爆发，厄尔尼诺南方涛动，准两年振荡相关的变化的稳健性，并特别关注11年太阳周期。分析涵盖平流层和对流层，涵盖1979-2009年期间。所有四个变异性来源的特征信号在数据集之间非常一致，并证实了先前分析中观察到的反应。一般来说，报告的太阳特征主要是由于观测的同化，而不是再分析系统中使用的基本预测模型。对平流层下部11年太阳响应的分析证实了赤道温度最大值的存在，尽管平流层上部的一致性较低，可能反映了那里同化数据的减少。太阳对极地急流振荡的调制也很明显，但只在2月才有意义。在对流层中，在所有的再分析中都可以看到纬向平均纬向风的垂直带状异常，30°N和30°S的东风异常表明在太阳活动极大期条件下存在较弱和可能较宽的Hadley环流。这种结构存在于年度信号中，在北半球冬季尤为明显。除了“自上而下”的太阳对北方环形模式变化的贡献外，我们还显示了来自表面条件的潜在贡献，允许"自下而上“的路径。最后，再分析与平流层探测单元（SSU）和CMIP-5最新大气环流模式观测到的全球平均温度进行了比较。SSU在三个不同的高度对平流层进行采样，并使用探测和归因技术在这些观测中识别出11年的太阳周期指纹。
A multiple linear regression analysis of nine different reanalysis datasets has been performed to test the robustness of variability associated with volcanic eruptions, the El Niño Southern Oscillation, the Quasi‐Biennial Oscillation and with a specific focus on the 11‐year solar cycle. The analysis covers both the stratosphere and troposphere and extends over the period 1979–2009. The characteristic signals of all four sources of variability are remarkably consistent between the datasets and confirm the responses seen in previous analyses. In general, the solar signatures reported are primarily due to the assimilation of observations, rather than the underlying forecast model used in the reanalysis system. Analysis of the 11‐year solar response in the lower stratosphere confirms the existence of the equatorial temperature maximum, although there is less consistency in the upper stratosphere, probably reflecting the reduced level of assimilated data there. The solar modulation of the polar jet oscillation is also evident, but only significant during February. In the troposphere, vertically banded anomalies in zonal mean zonal winds are seen in all the reanalyses, with easterly anomalies at 30°N and 30°S suggesting a weaker and possibly broader Hadley circulation under solar maximum conditions. This structure is present in the annual signal and is particularly evident in NH wintertime. As well as the ‘top‐down’ solar contribution to Northern Annular Mode variability, we show the potential contribution from the surface conditions allowing for a ‘bottom‐up’ pathway. Finally, the reanalyses are compared with both observed global‐mean temperatures from the Stratospheric Sounding Unit (SSU) and from the latest general circulation models from CMIP‐5. The SSU samples the stratosphere over three different altitudes, and the 11‐year solar cycle fingerprint is identified in these observations using detection and attribution techniques.