火星弓激波上游质子回旋波（PCW）是由太阳风和源自火星逃逸层拾起氢离子之间相互作用驱动的离子/离子不稳定性产生，因此研究火星上游PCW对理解火星逃逸层中性 氢损失以及水逃逸历史具有重要意义。自1989年首次发现PCW以来，PCW在常规太阳风 条件下的产生和性质已被广泛研究，但对于极端太阳风条件下，如行星际日冕物质抛射 （ICME）和太阳风流相互作用区（SIR）事件期间，PCW的活动很少受到关注，主要是 因为火星上游太阳风观测有限。火星大气与挥发物演化探测卫星（MAVEN）同时提供了 高分辨率的磁场和等离子体探测数据，为我们研究火星弓激波上游的太阳风结构及其中的低频等离子体波动提供了很好的机会。

在 本 论 文 中 ， 我 们 首 先 做 了 预 先 研 究 ， 即 利 用MAVEN数 据 证 认1.52 AU附 近 的24个ICME事件并给出列表，研究了火星附近的ICME的统计特征。其次，发展了基于小波分析和奇异值分解的PCW诊断程序。基于以上的研究和方法，我们统计分析 了2014年12月至2019年2月期间的ICME及其上下游扫过火星弓激波上游期间的PCW的性质变化。以类似的方式，我们分析了2014年10月至2021年8月MAVEN的观测数据，挑选 了第32-35火星年近日点季节期间的46个SIR事件，研究SIR及其上下游扫过火星弓激波上 游时PCW的波动性质及其与上游太阳风条件的关联，以此来揭示极端太阳风事件对火星上游PCW的影响。

本文主要的研究成果如下：

1. 给出了1.52 AU附近的行星际日冕物质抛射的列表及统计特征。 

由于火星上游的ICME特性尚未得到充分的探索，于是我们首先利用MAVEN数据 证认了2014年12月6日至2019年2月21日期间的24个ICME，基于ICME事件列表进行了统 计特性研究。（1）与长期平均值相比，ICME的磁场强度、密度和动压显著高于相应 的长期平均值，而ICME的速度略低于长期平均值，这表明在第24个太阳活动周的下降 阶段高速流占主导地位；（2）将ICME的统计特性与高速流、低速流和SIR的特征进行 了比较，结果表明：ICME中磁场强度最高、ICME的密度与SIR的密度相当、ICME的速度略低于SIR、ICME的动压小于SIR；（3）从1 AU到1.52 AU，ICME磁场强度的平均值从10.22 nT下降到5.99 nT、质子密度的平均值从7.81 cm⁻³到5.27 cm⁻³、质子速度的平均值 从436.60 km s⁻¹降至394.71 km s⁻¹、动压的平均值从2.34 nPa下降到1.34 nPa。

2. 发现行星际日冕物质抛射使得上游质子回旋波的发生率增大约20%、同时波动特征 显著增强。 

近日点季节（Ls=180°−360°）的PCW发生率远远高于远日点季节（Ls = 0 °−180°）。在近日点季节，ICME 阶段的PCW发生率（39%）大约是ICME上游阶段（17%） 和ICME下游阶段（20%）的2倍。ICME阶段的PCW波幅中值约是ICME上游和ICME下游 阶段的1.3倍，ICME阶段探测到的PCW相对于背景磁场方向以更小的角度传播，并且更接 近于圆极化，即展现出更明显的波动特性。

3. 发现太阳风流相互作用区使得上游质子回旋波的发生率增大约10%、同时波动特征 显著增强。 

在近日点季节，SIR阶段的PCW发生率（24%）大约是SIR上游阶段（14%）和SIR下 游阶段（13%）的1.8倍。此外，PCW往往更频繁地发生在SIR的前导部分中，具体来说， 前导部分发生率为31%、尾部为19%。类似于ICME，在SIR阶段探测到的PCW同样具有 更显著的波动特性，SIR阶段的PCW波幅中位数约是SIR上游和SIR下游阶段的1.6倍，并 且SIR阶段探测到的PCW以更平行于背景磁场的角度传播，且更接近于圆极化。

极端太阳风事件期间火星弓激波上游PCW发生率升高主要归因于新生质子的增多， 而这主要与两个因素有关：（1）太阳风质子和电子通量增加，从而通过电荷交换和电 子碰撞提高了外逸层H原子的电离率；（2）ICME 及其伴随的太阳高能粒子的额外电 离和加热（或SIR导致的增强的电离和加热）使得火星弓激波外的H原子密度上升。此 外，PCW发生率升高的部分原因可能是ICME/SIR阶段增强的动压使火星弓激波移动到较 低的高度，导致氢外逸层更多地暴露于太阳风中，且越低高度的外逸层H密度越大，从而 高密度的逃逸层中性氢得以与太阳风直接相互作用，进而加剧了逃逸层中的氢向空间中损失。

以上给出的量化结果不仅丰富了极端太阳风条件下火星弓激波上游PCW产生的具体 物理过程，而且揭示了太阳风事件对火星高层大气结构和大气损失产生的显著影响，从而有助于我们了解火星大气和水从早期到现在的演变过程。

Proton cyclotron waves (PCWs) upstream from Mars are generated by ion/ion instabilities due to the interaction between the solar wind and the pickup protons that originate from the extended hydrogen (H) exosphere of Mars, and thus have important implications for understanding the loss of H to interplanetary space and therefore the water escape history. They have attracted considerable attention since their initial detection in 1989, focusing primarily on their properties associated with the nominal solar wind. Little attention has been paid to PCW activity during extreme space weather events, such as interplanetary coronal mass ejections (ICMEs) and solar wind stream interaction regions (SIRs), largely because of limited upstream solar wind measurements. The Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft provides simultaneous high-resolution measurements of plasma and magnetic field, allowing the chance to characterize the solar wind, and to examine the low-frequency plasma waves in the medium upstream from the Martian bow shock, particularly for extreme solar wind conditions.

In this thesis, we start with a pre-study, identifying and cataloging the ICMEs using MAVEN data for the period from 2014 December 6 to 2019 February 21, and then examining the statistical properties of the 24 ICMEs. Next, we develop a PCW diagnostic procedure (i.e., a wave analysis method) based on wavelet analysis and singular value decomposition. Based on the results from our previous research, we further identify PCW events during the passage of ICMEs and their upstream and downstream regions, and obtain the PCW occurrence rate and main wave parameters, as well as their upstream solar wind conditions. In a similar manner, we analyze the PCW events during the passage of SIRs with the MAVEN measurements from October 2014 to August 2021. The 46 SIR events studied here are a subset of the events that occurred in the perihelion season (Ls=180°−360°) of Martian years 32-35. By comparing PCW occurrence rates and wave properties during extreme events and those at quiet times, we evaluate the potential impacts of extreme solar wind events on upstream PCW activity.

The main research results of this thesis are summarized as follows:

1. Identifying and cataloging the ICMEs at 1.52 AU and examining their statistical properties.

The properties of ICMEs near Mars have not yet been fully explored, thus we first identify 24 ICMEs from 2014 December 6 to 2019 February 21, then examine the statistical properties of these ICMEs. (1) On average, the magnetic field strength B, the density N and the dynamic pressure Pdy of ICMEs are significantly higher than the corresponding long-term mean values for the solar wind, whereas the velocity V of ICMEs is slightly slower than the long-term mean value for the solar wind, implying that high-speed streams are dominant in the solar wind during the declining phase of solar cycle 24. (2) The statistical properties of ICMEs are compared with high-speed streams, slow streams and SIRs. On average, the magnetic field strength B in ICMEs is the highest. The density N in ICMEs is also the largest, but its mean value is only about 0.10 cm⁻³ larger than that in SIRs. The velocity V of ICMEs is slightly lower than that of SIRs. The corresponding dynamic pressure Pdy of ICMEs is smaller than that of SIRs. (3) From 1 to 1.52 AU, the average of B in ICMEs decreases by a factor ∼1.70, from 10.22 to 5.99 nT. The average of N decreases by a factor ∼1.48, from 7.81 to 5.27 cm⁻³ . The average of V decreases by a factor ∼1.11, from 436.6 to 394.7 km s⁻¹ . The average of Pdy decreases by a factor ∼1.75, from 2.34 to 1.34 nPa.

2. ICMEs increase the PCW occurrence rate by approximately 20% as well as enhance wave properties.

It is found that PCWs occur more frequently during perihelion periods (Ls=180° -360°) than during aphelion periods (Ls=0°-180∘°) for disturbed times of ICME passage. In the perihelion season, the PCW occurrence rate is increased on average by a factor of about 2 during the ICME phase relative to the pre-ICME and post-ICME phases (from 17%∼20% to 39%). Moreover, PCWs reveal more pronounced wave characteristics, the median amplitude is increased by a factor of about 1.3 during the ICME phase relative to the pre-ICME and post-ICME phases, higher ellipticity and smaller propagation angle with respect to the ambient magnetic field direction during the ICME phase.

3. SIRs increase the PCW occurrence rate by approximately 10% as well as enhance wave properties.

It is found that the PCW occurrence rate is increased by a factor of about 1.8 (from 13%-14% to 24%) during the SIR phase relative to the pre-SIR and post-SIR phases. Furthermore, PCWs tend to occur more frequently in the leading portion of the SIR (∼31% of PCW occurrence rate for the leading portion of the SIR, compared to ∼19% for the trailing portion of the SIR). The median wave amplitude is enhanced by a factor of about 1.6 during the SIR phase relative to the pre-SIR and post-SIR phases. Similar to ICMEs, the PCWs observed during the SIR phase propagate at smaller angles to the background magnetic field, and are closer to being circularly polarized.

The increase in the PCW occurrence rate during the extreme solar wind events is attributed mainly to the enhanced production rates of newborn protons, resulting from two factors: (1) the elevated solar wind proton and electron fluxes and thus higher ionization rates of exospheric H atoms via charge exchange and electron impact, and (2) the increased exospheric H density above the Martian bow shock, as a result of additional ionization and heating from the ICMEs and the accompanying solar energetic particles (or enhanced ionization and heating from the SIRs). In addition, the increase of the PCW occurrence rate could be partly due to greater exposure of the hydrogen exosphere to the solar wind during the ICME/SIR intervals, when the bow shock moves to lower altitudes, where the exospheric H density is higher. These findings further reinforce the idea that space weather events can have a significant effect on exospheric H escape from Mars, and therefore the water escape history.