In the past decade, significant efforts have been made in developing physics-based solar wind and coronal mass ejection (CME) models, which have been or are being transferred to national centers (e.g., SWPC, CCMC) to enable space weather predictive capability. However, the input data coverage for space weather forecasting is extremely limited. One major limitation is the solar magnetic field measurements, which are used to specify the inner boundary conditions of the global magnetohydrodynamic (MHD) models. In this study, using the Alfven wave solar model (AWSoM), we quantitatively assess the influence of the magnetic field map input (synoptic/diachronic vs. synchronic magnetic maps) on the global modeling of the solar wind and the CME-driven shock in the 2013 April 11 solar energetic particle (SEP) event. Our study shows that due to the inhomogeneous background solar wind and dynamical evolution of the CME, the CME-driven shock parameters change significantly both spatially and temporally as the CME propagates through the heliosphere. The input magnetic map has a great impact on the shock connectivity and shock properties in the global MHD simulation. Therefore this study illustrates the importance of taking into account the model uncertainty due to the imperfect magnetic field measurements when using the model to provide space weather predictions.
We analyse the 2010 April 3rd CME using spacecraft coronagraphic images at different vantage points (SOHO, STEREO-A and STEREO-B). We perform a 3D reconstruction of both the flux rope and shock using the Graduated Cylindrical Shell (GCS) model to calculate CME kinematic and morphologic parameters (e.g. velocity, acceleration, radius). The obtained results are fitted with empirical models describing the expansion of the CME radius in the heliosphere and compared with in situ measurements from Wind spacecraft: the CME is found to expand linearly towards Earth. Finally, we relate the event with d…
This study examines the tail disconnection event on April 20, 2007 on comet 2P/Encke, caused by a coronal mass ejection (CME) at a heliocentric distance of 0.34 AU. During their interaction, both the CME and the comet are visible with high temporal and spatial resolution by the STEREO-A spacecraft. Previously, only current sheets or shocks have been accepted as possible reasons for comet tail disconnections, so it is puzzling that the CME caused this event. The MHD simulation presented in this work reproduces the interaction process and demonstrates how the CME triggered a tail disconnection i…
Context. We study two coronal mass ejections (CMEs) observed between April 1-2, 2019 by both the inner Wide-Field Imager for Parker Solar Probe (WISPR-I) and the inner heliospheric imager (HI-1) on board STEREO-A. This is the first study of CME observations from two viewpoints in similar directions but at considerably different solar distances. Aims. Our objective is to understand how the PSP observations affect the CME kinematics, especially due to its proximity to the Sun. Methods. We estimate the CME positions, speeds, accelerations, propagation directions and longitudinal deflections using…
We present the first analysis of internal coronal mass ejection (CME) structure observed very close to the Sun by the Wide-field Imager for Solar PRobe (WISPR) instrument on board Parker Solar Probe (PSP). The transient studied here is a CME observed during PSP's second perihelion passage on 2019 April 2, when PSP was only 40 R_sun from the Sun. The CME was also well observed from 1 au by the STEREO-A spacecraft, which tracks the event all the way from the Sun to 1 au. However, PSP/WISPR observes internal structure not apparent in the images from 1 au. In particular, two linear features are ob…
We study the kinematical characteristics and 3D geometry of a large-scale coronal wave that occurred in association with the 26 April 2008 flare-CME event. The wave was observed with the EUVI instruments aboard both STEREO spacecraft (STEREO-A and STEREO-B) with a mean speed of ~240 km/s. The wave is more pronounced in the eastern propagation direction, and is thus, better observable in STEREO-B images. From STEREO-B observations we derive two separate initiation centers for the wave, and their locations fit with the coronal dimming regions. Assuming a simple geometry of the wave we reconstruc…
Supra-arcade downflows (SADs) have been observed with Yohkoh/SXT (soft X-rays (SXR)), TRACE (extreme ultra-violet (EUV)), SoHO/LASCO (white light), SoHO/SUMER (EUV spectra), and Hinode/XRT (SXR). Characteristics such as low emissivity and trajectories which slow as they reach the top of the arcade are consistent with post-reconnection magnetic flux tubes retracting from a reconnection site high in the corona until they reach a lower-energy magnetic configuration. Viewed from a perpendicular angle, SADs should appear as shrinking loops rather than downflowing voids. We present XRT observations …
On 2020 April 19 a coronal mass ejection (CME) was detected in situ by Solar Orbiter at a heliocentric distance of about 0.8 AU. The CME was later observed in situ on April 20th by the Wind and BepiColombo spacecraft whilst BepiColombo was located very close to Earth. This CME presents a good opportunity for a triple radial alignment study, as the spacecraft were separated by less than 5$^\circ$ in longitude. The source of the CME, which was launched on April 15th, was an almost entirely isolated streamer blowout. STEREO-A observed the event remotely from -75.1$^\circ$ longitude, which is an e…
Propagation Characteristics of the April 21, 2023 CME
Indian Institute of Technology Gandhinagar（印度理工学院甘地纳加尔分校）；Physical Research Laboratory（物理研究实验室）；Indian Institute of Science Education and Research (IISER) Berhampur（印度科学教育与研究学院伯拉姆普尔分校）；NASA Goddard Space Flight Center（美国国家航空航天局戈达德太空飞行中心）
White light images of Coronal Mass Ejections (CMEs) are projections on the plane-of-sky (POS). As a result, CME kinematics are subject to projection effects. The error in the true (deprojected) speed of CMEs is one of the main causes of uncertainty to Space Weather forecasts, since all estimates of the CME Time-of-Arrival (ToA) at a certain location within the heliosphere require, as input, the CME speed. We use single viewpoint observations for 1037 flare-CME events between 1996-2017 and propose a new approach for the correction of the CME speed assuming radial propagation from the flare site…
In this paper, we analyze the full evolution, from a few days prior to the eruption to the initiation, and the final acceleration and propagation, of the CME that occurred on 2008 April 26 using the unprecedented high cadence and multi-wavelength observations by STEREO. There existed frequent filament activities and EUV jets prior to the CME eruption for a few days. These activities were probably caused by the magnetic reconnection in the lower atmosphere driven by photospheric convergence motions, which were evident in the sequence of magnetogram images from MDI (Michelson Doppler Imager) onb…
We present experimental evidence of the coronal mass ejection (CME) breakout reconnection, observed by the TESIS EUV telescope. The telescope could observe solar corona up to 2 $R_\odot$ from the Sun center in the Fe 171 Å line. Starting from 2009 April 8 TESIS, observed an active region (AR) that had a quadrupolar structure with an X-point 0.5 $R_\odot$ above photosphere. A reconstructed from the MDI data magnetic field also has a multipolar structure with an X-point above the AR. At 21:45 UT on April 9, the loops near the X-point started to move away from each other with a velocity of $\appr…
The rotation of erupting filaments in the solar corona is addressed through a parametric simulation study of unstable, rotating flux ropes in bipolar force-free initial equilibrium. The Lorentz force due to the external shear field component and the relaxation of tension in the twisted field are the major contributors to the rotation in this model, while reconnection with the ambient field is of minor importance. Both major mechanisms writhe the flux rope axis, converting part of the initial twist helicity, and produce rotation profiles which, to a large part, are very similar in a range of sh…
The solar wind transients propagating out in the inner heliosphere can be observed in white-light images from Heliospheric Imager-1 (HI1), an instrument of the Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) on board the Solar Terrestrial Relations Observatory (STEREO), from two perspectives. The spatial velocity distribution inside solar wind transients is key to understanding their dynamic evolution processes. We generated a velocity map of transients in 3D space based on 2D white-light images and used it to estimate the expansion rate as well as some kinematic propertie…
An intense type III radio storm has been disrupted by a fast halo coronal mass ejection (CME) on 2000 April 4. The CME is also associated with a large solar energetic particle (SEP) event. The storm recovers after about10 hrs. We identified another CME that occurs on 2003 November 11 with similar CME properties but there is no type III storm in progress. The 2003 November 11 CME is also not associated with an SEP event above the background (less than 2 pfu), whereas the one with type III storm has an intense SEP event (about 56 pfu). One of the factors affecting the intensity of SEP events is …
Aims. We present observations of the first coronal mass ejection (CME) observed at the Solar Orbiter spacecraft on April 19, 2020, and the associated Forbush decrease (FD) measured by its High Energy Telescope (HET). This CME is a multispacecraft event also seen near Earth the next day. Methods. We highlight the capabilities of HET for observing small short-term variations of the galactic cosmic ray count rate using its single detector counters. The analytical ForbMod model is applied to the FD measurements to reproduce the Forbush decrease at both locations. Input parameters for the model are…
We investigate the solar phenomena associated with the origin of the solar energetic particle (SEP) event observed on 2013 April 11 by a number of spacecraft distributed in the inner heliosphere over a broad range of heliolongitudes. We use Extreme UltraViolet (EUV) and white-light coronagraph observations from the Solar Dynamics Observatory (SDO), the SOlar and Heliospheric Observatory (SOHO) and the twin Solar TErrestrial RElations Observatory spacecraft (STEREO-A and STEREO-B) to determine the angular extent of the EUV wave and coronal mass ejection (CME) associated with the origin of the S…
We present a statistical analysis of coronal mass ejections (CMEs) imaged by the Heliospheric Imager (HI) instruments aboard NASAs twin-spacecraft STEREO mission between April 2007 and August 2017 for STEREO-A and between April 2007 and September 2014 for STEREO-B. The analysis exploits a catalogue that was generated within the FP7 HELCATS project. Here, we focus on the observational characteristics of CMEs imaged in the heliosphere by the inner (HI-1) cameras. More specifically, in this paper we present distributions of the basic observational parameters - namely occurrence frequency, central…
Coronal Mass Ejections (CMEs) drive space weather activity at Earth and throughout the solar system. Current CME-related space weather predictions rely on information reconstructed from coronagraphs, sometimes from only a single viewpoint, to drive a simple interplanetary propagation model, which only gives the arrival time or limited additional information. We present the coupling of three established models into OSPREI (Open Solar Physics Rapid Ensemble Information), a new tool that describes Sun-to-Earth CME behavior, including the location, orientation, size, shape, speed, arrival time, an…
The radial speed of a coronal mass ejection (CME) determines the shock-driving capability of a CME as indicated by the presence of a type II radio burst. Here we report on the April 18, 2014 CME that was associated with a type II radio burst in the metric and interplanetary domains. We used the radio-burst data provided by the San Vito Solar Observatory of the Radio Solar Telescope Network and data from the Wind spacecraft. The CME is a full halo in the field of view of the coronagraphs on board the Solar and Heliospheric Observatory (SOHO). The CME was also observed by the coronagraphs on boa…
Accurate space weather forecasting requires knowledge of the trajectory of coronal mass ejections (CMEs), including any deflections close to the Sun or through interplanetary space. Kay et al. 2013 introduced ForeCAT, a model of CME deflection resulting from the background solar magnetic field. For a magnetic field solution corresponding to Carrington Rotation (CR) 2029 (declining phase, April-May 2005), the majority of the CMEs deflected to the Heliospheric Current Sheet (HCS), the minimum in magnetic pressure on global scales. Most of the deflection occurred below 4 Rs. Here we extend ForeCA…
In this report we present two complex eruptive solar events and the associated Cosmic Ray effects (Forbush decrease). We use combined recordings from a number of Earthbound Receivers, Space Experiments and data archives (such as the ARTEMIS-IV Radio spectrograph, the Athens NEUTRON MONITOR, the LASCO CME Lists, the SONG of the {CORONAS-F} satellite, etc.). The influence of solar transients on the interplanetary medium conditions and the cosmic ray flux is analysed and discussed. The observed time sequence of events of this time period indicates that the initiation of CMEs is closely related to…
In this article, we present the multi-viewpoint and multi-wavelength analysis of an atypical solar jet based on the data from Solar Dynamics Observatory, SOlar, and Heliospheric Observatory, and Solar TErrestrial RElations Observatory. It is usually believed that the coronal mass ejections (CMEs) are developed from the large scale solar eruptions in the lower atmosphere. However, the kinematical and spatial evolution of the jet on 2013 April 28 guide us that the jet was clearly associated with a narrow CME having a width of approx 25 degrees with a speed of 450 km/s. To better understand the l…
Geometric modelling of Coronal Mass Ejections (CMEs) is a widely used tool for assessing their kinematic evolution. Furthermore, techniques based on geometric modelling, such as ELEvoHI, are being developed into forecast tools for space weather prediction. These models assume that solar wind structure does not affect the evolution of the CME, which is an unquantified source of uncertainty. We use a large number of Cone CME simulations with the HUXt solar wind model to quantify the scale of uncertainty introduced into geometric modelling and the ELEvoHI CME arrival times by solar wind structure…
MMS Insights into CME Driven Sub-Alfvénic Solar Wind at 1 AU
University of Maryland（马里兰大学）；NASA Goddard Space Flight Center（NASA戈达德太空飞行中心）；University of New Hampshire（新罕布什尔大学）；University of Delaware（特拉华大学）；University of Colorado Boulder（科罗拉多大学博尔德分校）
One of the grand challenges in heliophysics is the characterisation of coronal mass ejection (CME) magnetic structure and evolution from eruption at the Sun through heliospheric propagation. At present, the main difficulties are related to the lack of direct measurements of the coronal magnetic fields and the lack of 3D in-situ measurements of the CME body in interplanetary space. Nevertheless, the evolution of a CME magnetic structure can be followed using a combination of multi-point remote-sensing observations and multi-spacecraft in-situ measurements as well as modelling. Accordingly, we p…
Metric type II radio bursts are usually early indicators of CME-driven shocks and other space weather phenomena in the solar corona. This paper presents a detailed investigation of the spectral properties of band-splitting type II radio bursts and their association with sunspot number. Using type II radio bursts in a frequency range 20 to 200MHz observed by CALLISTO from 2010 to 2017, it was discovered that the analyzed type II shock height, magnetic field strength, CME shock speed, and Alfven speed synchronize with the trajectory of the solar cycle 24. Also, the study revealed that the onset …
A series of solar energetic particle (SEP) events were observed at Parker Solar Probe (PSP) by the Integrated Science Investigation of the Sun (\ISOIS) during the period from April 18, 2019 through April 24, 2019. The PSP spacecraft was located near 0.48 au from the Sun on Parker spiral field lines that projected out to 1 au within $\sim 25^\circ$ of near Earth spacecraft. These SEP events, though small compared to historically large SEP events, were amongst the largest observed thus far in the PSP mission and provide critical information about the space environment inside 1 au during SEP even…
We present an application of the stereoscopic self-similar-expansion model (SSSEM) to Solar Terrestrial Relations Observatory (STEREO)/Sun-Earth Connection Coronal and Heliospheric Investigation (SECCHI) observations of the 03 April 2010 CME and its associated shock. The aim is to verify whether CME-driven shock parameters can be inferred from the analysis of j-maps. For this purpose we use the SSSEM to derive the CME and the shock kinematics. Arrival times and speeds, inferred assuming either propagation at constant speed or with uniform deceleration, show good agreement with Advanced Composi…
We study three CME/ICME events (2008 June 1-6, 2009 February 13-18, 2010 April 3-5) tracked from Sun to 1 AU in remote-sensing observations of STEREO Heliospheric Imagers and in situ plasma and magnetic field measurements. We focus on the ICME propagation in IP space that is governed by two forces, the propelling Lorentz force and the drag force. We address the question at which heliospheric distance range the drag becomes dominant and the CME gets adjusted to the solar wind flow. To this aim we analyze speed differences between ICMEs and the ambient solar wind flow as function of distance. Th…
A post-CME current sheet (CS) is a common feature developed behind an erupting flux rope in CME models. Observationally, white light observations have recorded many occurrences of a thin ray appearing behind a CME eruption that closely resembles a post-CME CS in its spatial correspondence and morphology. UV and X-ray observations further strengthen this interpretation by the observations of high temperature emission at locations consistent with model predictions. The next question then becomes whether the properties inside a post-CME CS predicted by a model agree with observed properties. In t…
We present an investigation of an eruption event of coronal mass ejection (CME) magnetic flux rope (MFR) from source active region (AR) NOAA 11719 on 11 April 2013 utilizing observations from SDO, STEREO, SOHO, and WIND spacecraft. The source AR consists of pre-existing sigmoidal structure stacked over a filament channel which is regarded as MFR system. EUV observations of low corona suggest a further development of this MFR system by added axial flux through tether-cutting reconnection of loops at the middle of sigmoid under the influence of continuous slow flux motions during past two days. …
Assessing VBz variations during CME propagation: a preparatory study for the HENON mission using EUHFORIA
University of Calabria（卡拉布里亚大学）；NASA Goddard Space Flight Center（美国国家航空航天局戈达德太空飞行中心）；Goddard Planetary Heliophysics Institute, University of Maryland, Baltimore County（马里兰大学巴尔的摩分校戈达德行星日球物理研究所）；KU Leuven（荷语鲁汶大学）；University of Maria Curie-Skłodowska（玛丽亚·居里-斯克沃多夫斯卡大学）；National Institute for Astrophysics（国家天体物理研究所）；Space Dynamics Services S.R.L.（空间动力学服务有限公司）；Institute of Space Astrophysics and Planetology - INAF（空间天体物理学和行星学研究所（意大利国家天体物理研究所））；Università degli Studi di Firenze（佛罗伦萨大学）
We present SDO/AIA observation of three types of fast-mode propagating magnetosonic waves in a GOES C3.0 flare on 2013 April 23, which was accompanied by a prominence eruption and a broad coronal mass ejection (CME). During the fast rising phase of the prominence, a large-scale dome-shaped extreme ultraviolet (EUV) wave firstly formed ahead of the CME bubble and propagated at a speed of about 430 km/s in the CME's lateral direction. One can identify the separation process of the EUV wave from the CME bubble. The reflection effect of the on-disk counterpart of this EUV wave was also observed wh…
Measuring the physical parameters of Coronal Mass Ejections (CMEs), particularly their entrained magnetic field, is crucial for understanding their physics and for assessing their geo-effectiveness. At the moment, only remote sensing techniques can probe these quantities in the corona, the region where CMEs form and acquire their defining characteristics. Radio observations offer the most direct means for estimating the magnetic field when gyrosynchontron emission is detected. In this work we measure various CME plasma parameters, including its magnetic field, by modelling the gyrosynchrotron …
Reconstructing solar wind inhomogeneous structures from stereoscopic observations in white-light: Solar wind transients in 3D
CAS Key Laboratory of Geospace Environment, Department of Geophysics and Planetary Sciences, University of Science and Technology of China（中国科学院空间环境重点实验室，地球与行星科学学院，中国科学技术大学）；CAS Center for Excellence in Comparative Planetology, University of Science and Technology of China（中国科学院比较行星学卓越创新中心，中国科学技术大学）；Mengcheng National Geophysical Observatory, University of Science and Technology of China（蒙城国家地球物理观测台，中国科学技术大学）；SIGMA Weather Group, State Key Laboratory of Space Weather, Center for Space Science and Applied Research, Chinese Academy of Sciences（SIGMA天气研究组，空间天气国家重点实验室，空间科学应用研究中心，中国科学院）；Solar Physics and Space Plasma Research Center, School of Mathematics and Statistics, University of Sheffield（太阳物理与空间等离子体研究中心，数学与统计学院，谢菲尔德大学）
We study solar energetic particle (SEP) events during multiple solar eruptions. The analysed sequences, on 24-26 November 2000, 9-13 April 2001, and 22-25 August 2005, consisted of halo-type coronal mass ejections (CMEs) that originated from the same active region and were associated with intense flares, EUV waves, and interplanetary (IP) radio type II and type III bursts. The first two solar events in each of these sequences showed SEP enhancements near Earth, but the third in the row did not. We observed that in these latter events the type III radio bursts were stopped at much higher freque…
The physical conditions that determine whether or not solar active regions (ARs) produce strong flares and coronal mass ejections (CMEs) are not yet well understood. Here we investigate the association between electric-current neutralization, magnetic shear along polarity inversion lines (PILs), and eruptive activity in four ARs; two emerging and two well-developed ones. We find that the CME-producing ARs are characterized by a strongly non-neutralized total current, while the total current in the ARs that did not produce CMEs is almost perfectly neutralized. The difference in the PIL-shear be…
We report on the Atmospheric Imaging Assembly (AIA) observations of plasma outflows originating in a coronal dimming during the 2015 April 28th filament eruption. After the filament started to erupt, two flare ribbons formed, one of which had a well-visible hook enclosing a core (twin) dimming region. Along multiple funnels located in this dimming, a motion of plasma directed outwards started to be visible in the 171 and 193 filter channels of the instrument. In time-distance diagrams, this motion generated a strip-like pattern, which lasted for more than five hours and which characteristics d…
We report the result of the first search for multipoint in situ and imaging observations of interplanetary coronal mass ejections (ICMEs) starting with the first Solar Orbiter (SolO) data in 2020 April - 2021 April. A data exploration analysis is performed including visualizations of the magnetic field and plasma observations made by the five spacecraft SolO, BepiColombo, Parker Solar Probe (PSP), Wind and STEREO-A, in connection with coronagraph and heliospheric imaging observations from STEREO-A/SECCHI and SOHO/LASCO. We identify ICME events that could be unambiguously followed with the STER…
One of the most important products of solar flares are nonthermal energetic particles which may carry up to 50\% energy releasing in the flaring processes. In radio observations, nonthermal particles generally manifest as spectral fine structures with fast frequency drifting rates, named as solar fast drifting radio bursts (FDRBs). This work demonstrated three types of FDRBs, including type III pair bursts, narrow band stochastic spike bursts following the type III bursts and spike-like bursts superimposed on type II burst in an X1.3 flare on 2014 April 25. We find that although all of them ha…
It is well established that magnetic free energy associated with electric currents powers solar flares and coronal mass ejections (CMEs) from solar active regions (ARs). However, the conditions that determine whether an AR will produce an eruption are not well understood. Previous work suggests that the degree to which the driving electric currents, or the sum of all currents within a single magnetic polarity, are neutralized may serve as a good proxy for assessing the ability of ARs to produce eruptions. Here, we investigate the relationship between current neutralization and flare/CME produc…
Coronal mass ejections (CMEs) are a manifestation of the Sun's eruptive nature. They can have a great impact on Earth, but also on human activity in space and on the ground. Therefore, modelling their evolution as they propagate through interplanetary space is essential. EUropean Heliospheric FORecasting Information Asset (EUHFORIA) is a data-driven, physics-based model, tracing the evolution of CMEs through background solar wind conditions. It employs a spheromak flux rope, which provides it with the advantage of reconstructing the internal magnetic field configuration of CMEs. This is someth…
Sunward Streaming 3He-rich SEP Events Observed by Solar Orbiter and Parker Solar Probe during Perihelion Passage
Southwest Research Institute（西南研究所）；Center for Astrophysics—Harvard & Smithsonian（天体物理学中心——哈佛与史密森尼学会）；Space Radiation Laboratory, California Institute of Technology（加州理工学院空间辐射实验室）；Applied Physics Laboratory, Johns Hopkins University（约翰斯·霍普金斯大学应用物理实验室）；The University of Texas at San Antonio（得克萨斯大学圣安东尼奥分校）
A bright prominence associated with a coronal mass ejection (CME) was seen erupting from the Sun on 9 April 2008. This prominence was tracked by both the Solar Terrestrial Relations Observatory (STEREO) EUVI and COR1 telescopes, and was seen to rotate about the line of sight as it erupted; therefore, the event has been nicknamed the "Cartwheel CME." The threads of the prominence in the core of the CME quite clearly indicate the structure of a weakly to moderately twisted flux rope throughout the field of view, up to heliocentric heights of 4 solar radii. Although the STEREO separation was 48 d…
Solar flares and coronal mass ejections (CMEs), especially the larger ones, emanate from active regions (ARs). With the aim to understand the magnetic properties that govern such flares and eruptions, we systematically survey all flare events with GOES levels of >=M5.0 within 45 deg from disk center between May 2010 and April 2016. These criteria lead to a total of 51 flares from 29 ARs, for which we analyze the observational data obtained by the Solar Dynamics Observatory. More than 80% of the 29 ARs are found to exhibit delta-sunspots and at least three ARs violate Hale's polarity rule. The …
Many observations show that coronal holes (CHs) deviate coronal mass ejections (CMEs) away from them. However, there are some peculiar events reported where the opposite occurs. To contribute to a space weather forecast efforts, in relation to the prediction of CME trajectories, we study the interaction between flux ropes (FRs) and CHs through numerical simulations. We perform 2.5D numerical simulations where FRs and CHs interact with different relative polarity configurations. We also reconstruct the trajectory and magnetic environment of a peculiar event occurred on 30 April 2012. The numeri…
