Reconstruction of electron precipitation spectra at the top of the upper atmosphere using 427.8 nm auroral images

IF 3.4 2区物理与天体物理 Q2 ASTRONOMY & ASTROPHYSICS

Journal of Space Weather and Space Climate Pub Date : 2023-11-15 DOI:10.1051/swsc/2023028

Elisa Robert, Mathieu Barthelemy, Gael Cessateur, Angélique Woelfflé, Hervé Lamy, Simon Bouriat, Magnar Gullikstad Johnsen, Urban Brändström, Lionel Biree

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Abstract

We present an innovative method to reconstruct the characteristics of precipitated electrons in auroral regions from optical measurements. This method is based on an optimization implemented between numerical simulations of the Transsolo code and tomographic maps made from the Auroral Large Imaging System (ALIS) network. We focus on the Volume Emission Rate (VER) of the blue line N_{2}^{+} 1NG 427.8 nm, which is the most representative line of the energy deposition by electrons. The optimization is tested with the ALIS measurements carried out on March 05, 2008, at 18:41:30 UT and 18:42:40 UT. The reconstruction is performed by extracting the energy flux and the mean energy of the precipitating particles. Both Maxwellian and quasi-monoenergetic energy distributions are considered. Calculations performed with a Maxwellian energy distribution yielded an mean energy ranging from 1.8 to 5.2 keV with energy flux from 0.1 to 44.3 erg.cm^{-2}.s^{-1} for 18:41:30 UT, and an mean energy from 2.2 to 9.5 keV with energy flux from 2.1 to 136.7 erg.cm^{-2}.s^{-1} for 18:42:40 UT. Assuming a quasi-monoenergetic energy distribution, we find an mean energy of 4.2 to 11.82 keV with energy flux ranging from 0.1 to 45 erg.cm^{-2}.s^{-1} for 18:41:30 UT, and 8 to 17.1 keV with energy flux ranging from 2.2 to 110.1 erg.cm^{-2}.s^{-1} for 18:42:40 UT. Moreover, we show this method allows to reconstruct the energy characteristic of the precipitating electrons on a large region covering approximately 150 km by 150 km. This study also shows that some VER profiles of the maps are better fitted by a quasi mono-energetic distributions while some others correspond to broadband distributions. It appears clearly that the energy flux is linked to the column integrated intensity, the mean energy is linked with the peak altitude of the emission and the width of the energy distribution with the altitude thickness of the emissions.

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利用427.8 nm极光图像重建高层大气顶部电子沉淀谱

我们提出了一种创新的方法，从光学测量中重建极光区域中沉淀电子的特征。该方法基于Transsolo编码的数值模拟和aurora Large Imaging System (ALIS)网络的层析成像图之间的优化实现。我们重点研究了蓝线N_{2}^{+} 1NG 427.8 nm的体积发射率(VER)，这是电子能量沉积最具代表性的线。利用2008年3月5日18:41:30 UT和18:42:40 UT的ALIS测量结果对优化结果进行了验证。通过提取沉淀粒子的能量通量和平均能量进行重构。考虑了麦克斯韦和准单能能量分布。根据麦克斯韦能量分布进行计算，得到的平均能量范围为1.8至5.2 keV，能量通量为0.1至44.3 erg.cm^{-2}。在18:41:30 UT，平均能量为2.2 ~ 9.5 keV，能量通量为2.1 ~ 136.7 erg.cm^{-2}。s^{-1}为18:42:40 UT。假设准单能能量分布，我们发现平均能量为4.2 ~ 11.82 keV，能量通量为0.1 ~ 45 erg.cm^{-2}。在18:41:30 UT时为s^{-1}，能量通量为8 ~ 17.1 keV，能量通量为2.2 ~ 110.1 erg.cm^{-2}。s^{-1}为18:42:40 UT。此外，我们还表明，该方法可以重建大约150km × 150km大面积区域内沉淀电子的能量特征。该研究还表明，一些地图的VER剖面较好地符合准单能分布，而另一些则符合宽带分布。可以清楚地看出，能量通量与柱积分强度有关，平均能量与发射的峰值高度有关，能量分布的宽度与发射的高度厚度有关。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Journal of Space Weather and Space Climate ASTRONOMY & ASTROPHYSICS-GEOCHEMISTRY & GEOPHYSICS

CiteScore

6.90

自引率

6.10%

发文量

审稿时长

8 weeks

期刊介绍： The Journal of Space Weather and Space Climate (SWSC) is an international multi-disciplinary and interdisciplinary peer-reviewed open access journal which publishes papers on all aspects of space weather and space climate from a broad range of scientific and technical fields including solar physics, space plasma physics, aeronomy, planetology, radio science, geophysics, biology, medicine, astronautics, aeronautics, electrical engineering, meteorology, climatology, mathematics, economy, informatics.