Magnetosphere‐Ionosphere Coupling via Prescribed Field‐Aligned Current Simulated by the TIEGCM
Magnetosphere‐Ionosphere Coupling via Prescribed Field‐Aligned Current Simulated by the TIEGCM
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DOI：
10.1029/2020ja028665
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发表时间：
2020-12
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通讯作者：
A. Maute;A. Richmond;G. Lu;D. Knipp;Y. Shi;B. Anderson
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作者：
A. Maute;A. Richmond;G. Lu;D. Knipp;Y. Shi;B. Anderson
磁层-电离层（MI）耦合是模拟热层-电离层（TI）对地磁活动响应的关键。在大气环流模式（GCM）中，MI耦合通常是通过从例如经验或同化模式中指定离子对流和极光粒子降水模式来实现的。电离层电动力学同化测绘等同化模型的优点是，离子对流和极光粒子降水模式相互一致，并以现有观测为基础。然而，吸收大量不同的数据需要专业知识，并且非常耗时。另一方面，经验模型使用方便，但不能捕捉所有观察到的空间和时间变化。随着活动磁层和行星电动力学响应实验（AMPERE）数据的可用性，有机会在GCM中使用场向电流（FAC）来表示MI耦合。在这项研究中，我们将介绍一种新的方法，使我们能够使用所观察到的FAC在GCM和解决的半球间不对称的电位分布。我们比较了热层-电离层-电动力学环流模型（TIEGCM）模拟的磁暴期间使用新的方法和其他两种常用的方法来指定MI耦合的基础上经验和同化高纬度电位。的比较显示一般的相似性TI风暴时间响应和改进的时间变异性的新方法相比，使用经验模型，但结果也说明了实质性的差异，由于我们的不确定的知识MI耦合过程。
The magnetosphere‐ionosphere (MI) coupling is crucial in modeling the thermosphere‐ionosphere (TI) response to geomagnetic activity. In general circulation models (GCMs) the MI coupling is typically realized by specifying the ion convection and auroral particle precipitation patterns from for example, empirical or assimilative models. Assimilative models, such as the Assimilative Mapping of Ionospheric Electrodynamics, have the advantage that the ion convection and auroral particle precipitation patterns are mutually consistent and based on available observations. However, assimilating a large set of diverse data requires expert knowledge and is time consuming. Empirical models, on the other hand, are convenient to use, but do not capture all the observed spatial and temporal variations. With the availability of Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) data, there is an opportunity for employing field‐aligned currents (FAC) in GCMs to represent the MI coupling. In this study, we will introduce a new method which enables us to use observed FAC in GCMs and solve for the interhemispherically asymmetric electric potential distribution. We compare Thermosphere‐Ionosphere‐Electrodynamics General Circulation Model (TIEGCM) simulations of a geomagnetic storm period using the new approach and two other often‐used methods for specifying MI coupling based on empirical and assimilative high latitude electric potentials. The comparison shows general similarities of the TI storm time response and improved temporal variability of the new method compared to using empirical models, but results also illustrate substantial differences due to our uncertain knowledge about the MI coupling process.