Relationships between energetic storm particle events and interplanetary shocks driven by full and partial halo coronal mass ejections

We have analysed energetic storm particle (ESP) events in 116 interplanetary (IP) shocks driven by front-side full and partial halo coronal mass ejections (CMEs) with speeds $>$400 km s^?1during the years 1996–2015. We investigated the occurrence and relationships of ESP events with several parameters describing the IP shocks, and the associated CMEs, type II radio bursts, and solar energetic particle (SEP) events. Most of the shocks (57 %) were associated with an ESP event at proton energies $>$1 MeV.The shock transit speeds from the Sun to 1 AU of the shocks associated with an ESP event were significantly greater than those of the shocks without an ESP event, and best distinguished these two groups of shocks from each other. The occurrence and maximum intensity of the ESP events also had the strongest dependence on the shock transit speed compared to the other parameters investigated. The correlation coefficient between ESP peak intensities and shock transit speeds was highest (0.73 $\pm$ 0.04) at 6.2 MeV. Weaker dependences were found on the shock speed at 1 AU, Alfvénic and magnetosonic Mach numbers, shock compression ratio, and CME speed. On average all these parameters were significantly different for shocks capable to accelerate ESPs compared to shocks not associated with ESPs, while the differences in the shock normal angle and in the width and longitude of the CMEs were insignificant.The CME-driven shocks producing energetic decametric–hectometric (DH) type II radio bursts and high-intensity SEP events proved to produce also more frequently ESP events with larger particle flux enhancements than other shocks. Together with the shock transit speed, the characteristics of solar DH type II radio bursts and SEP events play an important role in the occurrence and maximum intensity of ESP events at 1 AU.     

Energetic particle signatures of geoeffective coronal mass ejections

We have studied statistically associations of moderate and intense geomagnetic storms with coronal mass ejections (CMEs) and energetic particle events. The goal was to identify specific energetic particle signatures, which could be used to improve the predictions of the geoeffectiveness of full and partial halo CMEs. Protons in the range 1–110 MeV from the ERNE experiment onboard SOHO are used in the analysis. The study covers the time period from August 1996 to July 2000. We demonstrate the feasibility of energetic particle observations as an additional source of information in evaluating the geoeffectiveness of full and partial halo CMEs. Based on the observed onset times of solar energetic particle (SEP) events and energetic storm particle (ESP) events, we derive a proxy for the transit times of shocks driven by the interplanetary counterparts of coronal mass ejections from the Sun to the Earth. For a limited number of geomagnetic storms which can be associated to both SEP and ESP signatures, we found that this transit time correlates with the strength of geomagnetic storms.     

Relative fluxes of shock and prompt peaks in SEP event time profiles

Peak fluxes are an important property of gradual solar energetic particle (SEP) event time profiles from both astro/heliophysical and applications perspectives. However, the peak flux in an event may occur at the event onset, or at the time of the interplanetary shock arrival (the ESP or energetic storm particles). This makes an important difference in the interpretation of the peak flux, and in any attempts to characterize or model it. This paper describes a study of SEP data sets from ACE, IMP-8 and GOES toward determining the relative properties of these peak fluxes for protons with energies near 1, 10, and 50 MeV. The results suggest that for gradual events with both peaks, the ESP peak often dominates at 1 MeV energies and is dominant about half the time at 10 MeV. Moreover, the prompt peak fluxes can be used to estimate the shock peak (ESP event) up to days ahead, especially in the lower energy range.     

等离子体鞘层效应对磁层探测电场仪设计的影响

在空间环境探测中,卫星与等离子体的相互作用会改变背景环境的粒子和电位的分布,从而影响探测器对空间电场的测量.为了给磁层卫星电场探测仪器的研制和设计提供参考,本文以中国未来的磁层电离层探测为背景,针对不同轨道高度的等离子体环境,利用SPIS (Spacecraft Plasma Interaction Software)...     

不透明度对太阳日冕软X射线OⅧ光谱线影响的研究

为研究不透明度对日冕软X射线的影响,利用光子逃逸因子的基本理论,分析了不透明度对太阳日冕OⅧ光谱线强度比的影响,讨论了OⅧ 1.879nm光谱线的光学厚度,估算了太阳等离子体中OⅧ离子的辐射层有效厚度. 结果表明,不透明度对太阳 OⅧ光谱线有较大影响,其辐射层有效厚度比其他太阳紫外谱线大. 此研究对太阳等离子体发射层特性诊断具有重要参考意义.      

Plasma sheet oscillations and their relation to substorm development: Cluster and double star TC1 case study

We examined two consecutive plasma sheet oscillation and dipolarization events observed by Cluster in the magnetotail, which are associated with a pseudo-breakup and a small substorm monitored by the IMAGE spacecraft. Energy input from the solar wind and an associated enhancement of the cross-tail current lead to current sheet thinning and plasma sheet oscillations of 3–5 min periods, while the pseudo-breakups occur during the loading phase within a spatially limited area, accompanied by a localized dipolarization observed by DSP TC1 or GOES 12. That is, the so-called “growth phase” is a preferable condition for both pseudo-breakup and plasma sheet oscillations in the near-Earth magnetotail. One of the plasma sheet oscillation events occurs before the pseudo-breakup, whereas the other takes place after pseudo-breakup. Thus there is no causal relationship between the plasma sheet oscillation events and pseudo-breakup. As for the contribution to the subsequent small substorm, the onset of the small substorm took place where the preceding plasma sheet oscillations can reach the region.     

Formation and characteristics of low latitude boundary layer

Characteristics of low latitude boundary layer (LLBL) of the Earth’s magnetosphere are investigated using data of Interball/Tail probe observations. The role of different processes of LLBL formation is discussed. The high level of magnetosheath turbulence is taken into account. It is shown that the turbulent nature of magnetic field and plasma fluctuations in the magnetosheath is one of the main factors determining the structure of LLBL. The results of Interball/Tail probe observations of the event 9 March 1996 are analyzed. The thickness of LLBL is determined for the number of cases. The change of LLBL thickness under the influence of the changes of solar wind parameters is investigated. It is shown that variability of solar wind conditions can be the important factor controlling LLBL thickness. Results of observations are compared with the theory which explains the value of LLBL thickness as the result of plasma transport inside the magnetosphere. It is shown that the theory gives the qualitative explanation of the observed dependence of LLBL thickness on solar wind parameters.     

等离子体彗尾动力学的数值研究

本文基于可压缩磁流体动力学模型,数值研究了尾瓣巾具有超Alfven速流动的等离子体彗尾的动力学特征。结果表明,等离子体片和尾瓣之间的剪切等离子体流动将会激发流动撕裂模不稳定性,引起彗尾等离子体片中发生磁场重联,形成磁岛和高密度的等离子体团。进而模拟了太阳风引起的局部驱动力对等离子体彗尾中磁场重联的影响,其特征时间远大于流动撕裂模。我们认为一些观测到的等离子体彗尾中的四块和彗尾截断事件可能主要与彗尾中剪切等离子体流动所引起的流动撕裂模不稳定性有关。      

磁层顶低混杂漂移不稳定性及等离子体幔、磁层对流的形成机制

磁层顶低混杂漂移不稳定性的理论和观测使我们可以提出一个新的磁层对流驱动模式,为了解释磁层对流的形成、磁层顶厚度等一系列磁层现象,已经提出了三种磁层模式,Dunge提出互联模式,认为行星际磁场磁力线与地磁场磁力线在磁层顶前部相互联接起来,磁层顶为一旋转间断面,太阳风粒子可直接通过磁层顶进入磁层内,虽然这一     

有限外磁场中的空心圆柱等离子体波导

分析了外磁场中电磁波沿空心圆柱等离子体波导的传播特性.首先给出边界条件的矩阵方程,利用矩阵的有关性质导出了问题的特征方程,采用精确求解特征方程的数值法,分析了波导传播常数随等离子体厚度、电子密度、碰撞频率和外加磁场的变化规律.      

Probing heliospheric diffusion coefficients with solar energetic particles

The dynamics of solar particle events provide a direct link to the understanding of properties of wave–particle interactions, and to the nature of the solar wind fluctuations. Depending on their energy, the often simultaneously observed electrons, protons and ions interact with different wavenumber ranges of the fluctuations, and are sensitive to various aspects of the dynamical nature of the solar wind turbulence. In general, the evolution of particle events is also sensitive to the spatial variation of the transport parameters between the Sun and a few AU. Together with in situ plasma and magnetic field observations this information can be used to extrapolate the properties of transport parameters into the more distant Heliosphere. Recent developments in the theory of parallel transport of energetic particles, and examples for the modelling of solar particle events and the derivation of transport parameters are considered. A dynamical quasi-linear theory is presented which gives special emphasis to the geometry and dynamic nature of the fluctuations, and which is able to provide particle mean free paths solely from observed plasma parameters, in good agreement with those derived by the modelling. Possibilities to apply the above results to the study of other energetic particle processes in the Heliosphere are discussed.     

月球的构造格架及其演化差异

根据以GRAIL重力场数据和LOLA地形数据计算的月壳厚度,将月球构造格架初步划分为三个构造单元:主要覆盖月球正面风暴洋区域的月海构造单元、主要覆盖月球背面高地的月陆构造单元以及主要位于南半球背面的南极艾肯盆地构造单元。结合最新的研究成果,对各构造单元上的重大地质事件包括岩浆事件、火山事件和撞击事件分别进行了简单的梳理,结果表明月球不同构造单元的演化事件具有明显的差异。     

A review of solar proton events during the 22nd solar cycle.

Solar cycle 22 had significant, large fluence, energetic particle events on a scale reminiscent of the 19th solar cycle. Examination of the characteristics of these large events suggests that some of the old concepts of spectral form, intensity-time envelope and energy extrapolations, used to estimate the dose from large events that occurred during previous solar cycles should be re-evaluated. There has also been a dramatic change in perspective regarding the source of solar protons observed in interplanetary space. Very large fluence events are associated with powerful fast interplanetary shocks. The elemental composition and charge state of these events is suggestive of a dominate source in the solar corona and not from a very hot plasma. Furthermore, there is a strong suggestion that the intensity-time profile observed in space is dominated by the connection of the observer to an interplanetary shock source rather than to a unique location near the surface of the sun. These concepts will be examined from the perspective of energetic particles contributing to the dose experienced by an astronaut on an interplanetary space mission.     

SABRE雷达及其观测的Pc5地磁脉动Ⅰ.统计分析结果

本文简要介绍了相干散射雷达SABRE及其观测Pc5地磁脉动的工作原理。1985—1989年观测数据的统计分析结果表明,相位向极传播脉动事件的出现率峰值在当地时间午夜附近,而向赤道传播事件的出现率峰值则在18:00LT左右。文中给出了上述两类脉动事件出现率的日变化,与地磁活动的相关,与背景电离层等离子体对流特性的关系等统计分析结果。     

Solar cycle and latitude dependence of high-beta suprathermal plasma conditions in interplanetary space between 1.3 and 5.4 AU

The analysis of energetic particles and magnetic field measurements from the Ulysses spacecraft has shown that in a series of events, the energy density contained in the suprathermal tail particle distribution is comparable to or larger than that of the magnetic field, creating conditions of high-beta plasma. In this work we analyze periods of high-beta suprathermal plasma occurrences (β_ep > 1) in interplanetary space, using the ratio (β_ep) of the energetic particle (20 keV to ∼5 MeV) and magnetic field energy densities from measurements covering the entire Ulysses mission lifetime (1990–2009) in order to reveal new or to reconfirm some recently defined interesting characteristics. The main key-results of the work are summarized as follows: (i) we verify that high-beta events are detected within well identified regions corresponding mainly to the vicinity of shock surfaces and magnetic structures, and associated with energetic particle intensity enhancements due to (a) reacceleration at shock-fronts and (b) unusually large magnetic field depressions. (ii) We define three considerable features for the high-beta events, concentrated on the next points: (a) there is an appreciable solar-activity influence on the high-beta events, during the maximum and middle solar-cycle phase, (b) the annual peak magnitude and the number of occurrences of high events are well correlated with the sunspot number, (c) the high-beta suprathermal plasma events present a spatial distribution in heliographic latitudes (HL) up to ∼±80°, and a specific important concentration on the low (−25° ? HL < −6°, 6° < HL ? 25°) and median (−45° ? HL < −25°, 25° < HL ? 45°) latitudes. We also reconfirm by a statistical analysis the results of Marhavilas and Sarris (2011), that the high-beta suprathermal plasma (β_ep > 1) events are characterized by a very large parameter β_ep (up to 1732.5), a great total duration (406 days) and a large percentage of the Ulysses-mission lifetime (which is equal to 6.34% of the total duration with usable measurements, and 11.3% of the duration in presence of suprathermal particles events).     

Combining MHD and kinetic modelling of solar flares

Solar flares are explosive events in the solar corona, representing fast conversion of magnetic energy into thermal and kinetic energy, and hence radiation, due to magnetic reconnection. Modelling is essential for understanding and predicting these events. However, self-consistent modelling is extremely difficult due to the vast spatial and temporal scale separation between processes involving thermal plasma (normally considered using magnetohydrodynamic (MHD) approach) and non-thermal plasma (requiring a kinetic approach). In this mini-review we consider different approaches aimed at bridging the gap between fluid and kinetic modelling of solar flares. Two types of approaches are discussed: combined MHD/test-particle (MHDTP) models, which can be used for modelling the flaring corona with relatively small numbers of energetic particles, and hybrid fluid-kinetic methods, which can be used for modelling stronger events with higher numbers of energetic particles. Two specific examples are discussed in more detail: MHDTP models of magnetic reconnection and particle acceleration in kink-unstable twisted coronal loops, and a novel reduced-kinetic model of particle transport in converging magnetic fields.     

基于传输矩阵法的等离子体鞘套传输特性分析

引入分层模型传输矩阵法,分析高速临近空间飞行器等离子体鞘套传输特性.通过对典型飞行器模型进行纳维-斯托克斯方程组数值求解,仿真了等离子体鞘套的流场电子密度分布,分析了电磁波在等离子体鞘套内传输时的衰减常数,给出信号传输的反射系数和透射系数.基于传输矩阵法的仿真结果与理论分析结果和时域有限差分法仿真分析结果有良好的一致性,同时,该方法有效降低了计算复杂度,适用于任意电子密度分布和厚度的等离子体鞘套传输特性的数值求解.      

瑞利激光雷达探测北京上空中间层低逆温层

利用延庆瑞利激光雷达（40.47°N,115.97°E）2012年1-2月及2012年5月至2013年4月的探测数据,分析得到北京上空60～80km高度140个晚间的温度廓线,对这一区域内的低中间层逆温层现象（Lower Mesospheric Inversion Layer,Lower MIL）进行了统计分析,发现平均逆温幅度为23.4K,平均垂直尺度为4.78km,逆温层底部平均高度为68.2km.约有2/3的逆温层存在随时间垂直传播现象,且大多为向下传播.此外,还观测到三个垂直传播速度相差近一倍的特殊双低层MIL演化现象.      

燕尾榫连接结构微动疲劳全寿命预测方法

微动损伤使航空发动机榫连接结构疲劳寿命显著降低。以钛合金Ti-6Al-4V燕尾榫连接结构为例,提出一种适用于复杂结构微动疲劳全寿命预测方法。基于修正的Manson-McKnight方法和多轴疲劳理论,疲劳损伤参数由等效应力参数（ESP）表征,微动疲劳裂纹萌生位置和成核寿命通过有限元分析（FEA）和ESP预测。基于断裂力学理论和最大周向应力准则,提出微动疲劳裂纹扩展数值模拟方法,建立微动疲劳扩展寿命与裂纹长度函数关系,依据裂纹终值长度预测微动疲劳扩展寿命。结果显示:钛合金Ti-6Al-4V燕尾榫连接结构微动疲劳裂纹扩展角预测值与实验值均为18°,裂纹生长方向预测值与实验值相符;微动疲劳全寿命（成核寿命+扩展寿命）预测值在实验值的2倍分散带内;最大拉伸载荷对榫连接结构的微动疲劳全寿命影响显著,在相同应力比下,最大拉伸载荷从18 kN变化到24 kN,钛合金Ti-6Al-4V燕尾榫连接结构微动疲劳全寿命降低1个数量级。      

A new parameter to define interplanetary coronal mass ejections

The interplanetary manifestations of coronal mass ejections, ICMEs, have many signatures in the solar wind but none of these signatures in the velocity, density, temperature, magnetic field, plasma composition or energetic particles uniquely and unambiguously identifies the occurrence of an ICME. Different investigators identify different events when confronted with the same data. Herein, we present a single physical parameter that combines information from multiple plasma components and that holds the promise of defining a beginning and an end of the region of influence ICME and an indication of the location of the encounter with the ICME relative to its central meridian. This parameter is the total plasma pressure perpendicular to the magnetic field, consisting of the sum of the magnetic pressure and plasma kinetic or thermal pressure. It provides a vehicle for classifying the nature of the ICME encounter and, in many cases, provides an unambiguous start and stop time of the event. However, it does not provide a start and stop time for any embedded flux rope. This identification depends on examination of the magnetic field.