On the Importance of Using Event‐Specific Wave Diffusion Rates in Modeling Diffuse Electron Precipitation
On the Importance of Using Event‐Specific Wave Diffusion Rates in Modeling Diffuse Electron Precipitation
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DOI：
10.1029/2021ja029918
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发表时间：
2022-04
期刊：
影响因子：
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通讯作者：
Yiqun Yu;K. Hosokawa;B. Ni;V. Jordanova;Y. Miyoshi;Jinbin Cao;X. Tian;Long Ma
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文献类型：
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作者：
Yiqun Yu;K. Hosokawa;B. Ni;V. Jordanova;Y. Miyoshi;Jinbin Cao;X. Tian;Long Ma
几到几十keV的电子沉淀将大量能量带到高层大气中，形成极光，这是一个重要的磁层-电离层耦合过程。降水通常是由与磁层中的等离子体波相关的散射过程引起的。散射过程通常用波扩散速率来量化，它表示电子被散射的速度有多快。全球模型通常使用从统计波浪模型得出的扩散系数。然而，由于统计的性质，许多局部的、瞬时的特征可能会被抹掉。在这项研究中，我们使用事件特定的扩散系数来研究电子沉淀，这些扩散系数是基于同时现场测量/推断的，而不是统计的合唱波动力学获得的。我们发现，与使用统计系数相比，与更动态和更强烈的合唱波模型相关联的事件特定扩散系数的应用会导致更多的电子，特别是在L的黎明到中午区域的几到几十keV的电子。新的模拟大致捕捉到了NOAA/POES卫星探测到的降水通量的强度和变化性。中纬度Millstone Hill雷达在低E区(100-120公里)观测到的电离层电子密度也得到了更好的再现，而使用统计扩散系数的情况低估了电离率。这项研究表明，使用特定于事件的扩散速率在模拟弥散电子沉淀和理解磁层-电离层耦合方面具有重要意义。
A few to tens of keV electron precipitation that carries substantial energy source down to the upper atmosphere to create aurora is manifested as an important magnetosphere‐ionosphere coupling process. The precipitation is usually caused by scattering processes associated with plasma waves in the magnetosphere. The scattering process is often quantified by wave diffusion rates that indicate how fast an electron is scattered. Global models commonly use diffusion coefficients that are derived from statistical wave models. However, due to the statistical nature, many localized, transient features could be smeared out. In this study, we investigate electron precipitation using event‐specific diffusion coefficients that are obtained based on simultaneous in‐situ measured/inferred, rather than statistical, chorus wave dynamics. We find that the application of the event‐specific diffusion coefficients associated with a more dynamic and intense chorus wave model leads more electrons, particularly at several to tens of keV in the dawn‐to‐noon sector at L > 3, to precipitate than using statistical coefficients. The new simulation roughly captures both the intensity and variability of the precipitating flux as detected by the NOAA/POES satellites. Ionospheric electron density in the lower E region (100–120 km) observed by the mid‐latitude Millstone Hill radar is also much better reproduced, while the case using statistical diffusion coefficients underestimates the ionization rate. This study implies the importance of using event‐specific diffusion rates in simulating the diffuse electron precipitation and understanding the magnetosphere‐ionosphere coupling.