The Influence of Internal Atmospheric Variability on the Ionosphere Response to a Geomagnetic Storm
The Influence of Internal Atmospheric Variability on the Ionosphere Response to a Geomagnetic Storm
复制标题
内部大气变率对地磁暴电离层响应的影响
DOI：
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发表时间：
2018
期刊：
影响因子：
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通讯作者：
H. Liu
中科院分区：
文献类型：
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作者：
N. Pedatella;H. Liu
扩展的全大气社区气候模型被用于研究在多大程度上忽略实际的逐日低层大气变率会给电离层对理想化地磁暴的响应带来不确定性。通过在地磁暴发生前30天在低层大气中添加小的温度扰动，生成了一个由10个成员组成的集合。混沌发散以及内部大气变率导致每个集合成员在地磁暴发生时处于一种任意不同但气候相似的大气状态。我们用集合标准差来表征的总电子含量逐日变化的集合内变率，在地磁平静时期通常约为10% - 20%。在一次Kp为7的理想化地磁暴期间，总电子含量变化的集合标准差在低纬度和中纬度增加到约20% - 40%，局部区域超过100%。对单个集合成员的研究表明，它们都捕捉到了电离层暴时变化的相同大尺度特征，但在区域上可能表现出显著（50%）的差异，特别是在暴的后期阶段。因此，结果表明，为了准确捕捉高层大气对地磁暴响应的小尺度特征，有必要考虑低层大气变率的影响。
The Whole Atmosphere Community Climate Model eXtended is used to investigate the extent to which neglecting the realistic day‐to‐day lower atmospheric variability introduces uncertainty in the ionosphere response to an idealized geomagnetic storm. A 10‐member ensemble is generated by adding small temperature perturbations in the lower atmosphere 30 days prior to the imposed geomagnetic storm. Chaotic divergence, and internal atmospheric variability, leads to the geomagnetic storm occurring under an arbitrarily different, though climatically similar, atmospheric state for each ensemble member. The intra‐ensemble variability, which we characterize by the ensemble standard deviation, of the day‐to‐day change in total electron content is generally ∼10%–20% during geomagnetically quiet time. During an idealized storm with a Kp of 7 the ensemble standard deviation of the change in total electron content increases to ∼20%–40% at low and middle latitudes, with localized regions exceeding 100%. Examination of individual ensemble members illustrates that they all capture the same large‐scale features of the storm time changes in the ionosphere but can exhibit notable (50%) differences regionally, especially during later stages of the storm. The results thus demonstrate that in order to accurately capture smaller‐scale features of the upper atmosphere response to geomagnetic storms, it is necessary to include the effects of lower atmosphere variability.