Coronal Mass Ejections

This workshop summary tries to distill the key difficulties and questions in the art of (I)CME physics and strategies to address them. (I)CMEs are multi-dimensional, multi-parameter, and multi-scale phenomena related to the solar dynamo, corona, and heliosphere. This workshop illustrates the immense progress made in describing and modeling these spectacular energetic solar events, but also shows clear shortcomings in our understanding of them.     

The coronal context of transition region explosive events

Transition region explosive events are observed throughout the quiet Sun and represent an interesting local heating phenomenon. The coronal counterparts of these events, if they exist, were not observed in a sounding rocket campaign dedicated to this objective. The coronal instrument complement on the SOHO spacecraft provides an opportunity to extend this search for the coronal counterparts of the transition region explosive events, as well as to explore the correspondence of explosive events with large scale coronal structures, such as with coronal dark lanes.     

A statistical study of post-flare-associated CME events

We present a statistical study of post-flare-associated CMEs (PFA-CMEs) during the period from 1996 to 2010. By investigating all CMEs and X-ray flares, respectively, in the LASCO and GOES archives, we found 15875 CMEs of which masses are well measured and 25112 X-ray flares of which positions are determined from their optical counterparts. Under certain temporal and spatial criteria of these CMEs and solar flare events, 291PFA-CMEs events have been selected. Linking the flare fluxes with CME speeds of these paired events, we found that there is a reasonable positive linear relation between the CME linear speed and associated flare flux. The results show also the CME width increases as the flux of its associated solar flare increases. Besides we found that there is a fine positive linear relation between the CME mass and its width. Matching the flare fluxes with CME masses of these paired events, we find the CME mass increases as the flux of its associated solar flare increases. Finally we find the PFA-CME events are in regular more decelerated than the other CMEs.     

Pseudo-automatic characterization of the morphological and kinematical properties of coronal mass ejections using a texture-based technique

The white light coronagraphs onboard SOHO (LASCO-C2 and -C3) and most recently STEREO (SECCHI -COR1 and -COR2) have detected a myriad of coronal mass ejections (CME). They are a key component of space weather and under certain conditions they can become geo-effective, hence the importance of their kinematic characterization to help predict their effects. However, there is still a lot of debate on how to define the event boundaries for space weather purposes, which in turn makes it difficult to agree on their kinematic properties. That lack of agreement is reflected in both the manual and automated CME catalogs in existence. To contribute to a more objective definition and characterization of white-light coronagraph events, Goussies et al. (2010) introduced recently the concept of “texture of the event”. Based on that property, they developed a supervised segmentation algorithm to allow the automatic tracking of dynamic events observed in the coronagraphs field of view, which is called CORonal SEgmentation Technique (CORSET). In this work, we have enhanced the capabilities of the algorithm by adding several new functionalities, namely the automatic computation of different morphological and kinematic parameters. We tested its performance on 57 well-studied limb CME events observed with the LASCO coronagraphs between 1997 and 2001, and compared the parameters obtained with those from three existent CME lists: two of them obtained from an observer-based detection and tracking method (i.e., two manual catalogs), and the other one based on the automated detection and characterization of the CME events (i.e., a fully automated catalog). We found that 51 events could be tracked and quantified in agreement with the CME definition. In general terms, the position angle, and the radial and expansion speeds are in agreement with the manual catalogs used for comparison. On the other hand, some discrepancies between CORSET and the automated catalog were found, which can be explained by the different delimitation of the CME angular extent.     

CME–flare association during the 23rd solar cycle

The relation between coronal mass ejections (CMEs) and solar flares are statistically studied. More than 10,000 CME events observed by SOHO/LASCO during the period 1996–2005 have been analyzed. The soft X-ray flux measurements provided by the Geostationary Operational Environmental Satellite (GOES), recorded more than 20,000 flares in the same time period. The data is filtered under certain temporal and spatial conditions to select the CME–flare associated events. The results show that CME–flare associated events are triggered with a lift-off time within the range 0.4–1.0 h. We list a set of 41 CME–flare associated events satisfying the temporal and spatial conditions. The listed events show a good correlation between the CME energy and the X-ray flux of the CME–flare associated events with correlation coefficient of 0.76.     

Research Advances of Solar Corona and Interplanetary Physics in China: 2012–2014

Solar transients and their related interplanetary counterparts have severe effects on the space environments of the Earth. Therefore, the research of solar corona and interplanetary physics has become the focus of study for both solar and space scientists. Considerable progress has been achieved in these aspects by the solar and space physics community of China during 2012–2014, which will be given in this report. The brief report summarizes the research advances of solar corona and interplanetary physics into the following parts: solar wind origin and turbulence, coronal waves and seismology, solar eruptions, solar energetic particle and galactic cosmic ray, magnetic reconnection,Magnetohydrodynamic(MHD) models and their applications, waves and structures in solar wind,propagation of ICMEs/shocks and their arrival time predictions. These research achievements have been achieved by Chinese solar and space scientists independently or via international collaborations.     

有源多假目标干扰的极化识别新方法

提出一种利用单脉冲跟踪雷达的和、差波束特性差异的极化估计算法。基于目标散射回波和固定转发式有源假目标干扰产生物理机理的差异,设计了极化相似测度、极化相关系数、极化欧式距离等干扰鉴别参量,提出了有源假目标干扰鉴别算法。该技术无需增加极化通道,降低了计算和处理难度,更易工程实现。仿真结果证明了该方法的有效性。     

基于CPU/GPU的日冕偏振亮度并行计算模型

三维磁流体力学(MHD)数值模拟是用来研究日冕和太阳风最常用的方法之一, 其中将计算得到的日冕电子数密度转化为日冕偏振亮度(Polarization Brightness, PB)是与观测对比的重要方法. 由于待转换电子数据网格密度、PB数据网格密度和计算模型的复杂度, 使得日冕偏振亮度的计算比较耗时, 利用单CPU计算无法达到近实时转换日冕偏振亮度的要求, 从而影响了数值模拟的验证效率. 本文在CPU/GPU环境下, 利用CUDA编程技术, 提出了一个日冕偏振亮度并行计算模型. 实验结果表明, 该模型比CPU上的串行模型计算速度提高了31.86倍, 达到了近实时模拟与观测数据比对的计算要求.      

干涉型光纤安防系统偏振误差机理分析

对应用于安全防范、石油管道监测的双马赫-曾德型光纤安防系统的结构及工作原理进行分析.针对现场测试结果,分析了影响系统精度的误差因素,提出影响系统精度和增加误报率主要是由于偏振态变化不一致导致的两路干涉信号幅值波动以及附加相位噪声引入的距离定位误差.并展开对系统偏振衰落形成机理及其主要影响因素的定量定性分析,同时建立数学模型,进行仿真计算.最后通过对双马赫-曾德型光纤安防系统样机进行实验,验证了分析结果的正确性.     

A study of a long duration B9 flare-CME event and associated shock

We present and discuss here the observations of a small long duration GOES B-class flare associated with a quiescent filament eruption, a global EUV wave and a CME on 2011 May 11. The event was well observed by the Solar Dynamics Observatory (SDO), GONG H$\alpha$, STEREO and Culgoora spectrograph. As the filament erupted, ahead of the filament we observed the propagation of EIT wave fronts, as well as two flare ribbons on both sides of the polarity inversion line (PIL) on the solar surface. The observations show the co-existence of two types of EUV waves, i.e., a fast and a slow one. A type II radio burst with up to the third harmonic component was also associated with this event. The evolution of photospheric magnetic field showed flux emergence and cancellation at the filament site before its eruption.