To investigate the dependence of large gradual solar energetic particle（SEP） events on the associated flares and coronal mass ejections（CMEs）, the correlation coefficients（CCs） between peak intensities of E 〉 1...To investigate the dependence of large gradual solar energetic particle（SEP） events on the associated flares and coronal mass ejections（CMEs）, the correlation coefficients（CCs） between peak intensities of E 〉 10 MeV（I10）, E 〉 30 MeV（I30） and E 〉 50 MeV（I50） protons and soft X-ray（SXR） emission of associated flares and the speeds of associated CMEs in the three longitudinal areas W0–W39, W40–W70（hereafter the well connected region） and W71–W90 have been calculated.Classical correlation analysis shows that CCs between SXR emission and peak intensities of SEP events always reach their largest value in the well connected region and then decline dramatically in the longitudinal area outside the well connected region, suggesting that they may contribute to the production of SEPs in large SEP events. Both classical and partial correlation analyses show that SXR fluence is a better parameter describing the relationship between flares and SEP events. For large SEP events with source location in the well connected region, the CCs between SXR fluence and I10, I30 and I50 are0.58±0.12, 0.80±0.06 and 0.83±0.06 respectively, while the CCs between CME speed and I10, I30 and I50 are 0.56±0.12, 0.52±0.13 and 0.48±0.13 respectively. The partial correlation analyses show that in the well connected region, both CME shock and SXR fluence can significantly affect I10, but SXR peak flux makes no additional contribution. For E 〉 30 MeV protons with source location in the well connected region, only SXR fluence can significantly affect I30, and the CME shock makes a small contribution to I30, but SXR peak flux makes no additional contribution. For E 〉 50 MeV protons with source location in the well connected region, only SXR fluence can significantly affect I50, but both CME shock and SXR peak flux make no additional contribution. We conclude that these findings provide statistical evidence that for SEP events with source locations in the well connected region, a CME shock is only an effective accelerator for E 〈 30 MeV protons. However, flares are not only effective accelerators for E 〈 30 MeV protons, but also for E 〉 30 MeV protons, and E 〉 30 MeV protons may be mainly accelerated by concurrent flares.展开更多
Sympathetic coronal mass ejections (CMEs) usually occur in different active regions connected by interconnecting magnetic loops, while homologous CMEs occur within the same active region with an almost the same backgr...Sympathetic coronal mass ejections (CMEs) usually occur in different active regions connected by interconnecting magnetic loops, while homologous CMEs occur within the same active region with an almost the same background magnetic field, and so are similar in shapes. Two sympathetic CMEs erupted within 3 hours on 2002 May 22, originating from the same active region, AR 9948. Their multi-wavelength data were collected and analyzed. It is suggested that emerging flux triggered the occurrence of the first CME and the corresponding flare, the reconnection inflow of which in turn triggered the eruption of the second CME. Based on the fact that the two sympathetic CMEs have many similarities, in their shapes, their low-lying dimming areas, etc., we tentatively propose, for the first time, the phenomenon of sympathetic homologous CMEs.展开更多
To investigate the possible solar source of high-energy protons, correlation coefficients between the peak intensities of E ≥ 100 MeV protons, I100, and the peak flux and fluence of solar soft X-ray（SXR） emission, ...To investigate the possible solar source of high-energy protons, correlation coefficients between the peak intensities of E ≥ 100 MeV protons, I100, and the peak flux and fluence of solar soft X-ray（SXR） emission, and coronal mass ejection（CME） linear speed in the three longitudinal areas W0-W39, W40-W70 and W71-W90 have been calculated respectively. Classical correlation analysis shows that the correlation coefficients between CME speeds and I100 in the three longitudinal areas are0.28±0.21, 0.35±0.21 and 0.04±0.30 respectively. The classical correlation coefficients between I100 and SXR peak flux in the three longitudinal areas are 0.48±0.17, 0.72±0.13 and 0.02±0.30 respectively, while the correlation coefficients between I100 and SXR fluence in the three longitudinal areas are 0.25±0.21, 0.84±0.07 and 0.10±0.30 respectively. Partial correlation analysis shows that for solar proton events with source location in the well connected region（W40-W70）, only SXR fluence can significantly affect the peak intensity of E ≥ 100 MeV protons, but SXR peak flux has little influence on the peak intensities of E ≥ 100 MeV protons; moreover, CME speed has no influence on the peak intensities of E ≥ 100 MeV protons. We conclude that these findings provide statistical evidence that E ≥ 100 MeV protons may be mainly accelerated by concurrent flares.展开更多
Recently, S. W. Kahler studied the timescales of solar energetic particle （SEP） events asso- ciated with coronal mass ejections （CMEs） from analysis of spacecraft data. They obtained different timescales for SEP e...Recently, S. W. Kahler studied the timescales of solar energetic particle （SEP） events asso- ciated with coronal mass ejections （CMEs） from analysis of spacecraft data. They obtained different timescales for SEP events, such as TO, the onset time from CME launch to SEP onset, TR, the rise time from onset to half the peak intensity （0.5/p）, and TD, the duration of the SEP intensity above 0.5Ip. In this work, we solve the transport equation for SEPs considering interplanetary coronal mass ejection （ICME） shocks as energetic particle sources. With our modeling assumptions, our simulations show similar results to Kahler＇s analysis of spacecraft data, that the weighted average of TD increases with both CME speed and width. Moreover, from our simulation results, we suggest TD is directly dependent on CME speed, but not dependent on CME width, which were not found in the analysis of observational data.展开更多
We analyzed the speed （v） distributions of 11584 coronal mass ejections （CMEs） observed by the Large Angle and Spectrometric Coronagraph Experiment on board the Solar and Heliospheric Observatory （SOHO/LASCO） in...We analyzed the speed （v） distributions of 11584 coronal mass ejections （CMEs） observed by the Large Angle and Spectrometric Coronagraph Experiment on board the Solar and Heliospheric Observatory （SOHO/LASCO） in cycle 23 from 1996 to 2006. We find that the speed distributions for high-latitude （HL） and low-latitude （LL） CME events are nearly identical and to a good approximation they can be fitted with a lognormal distribution. This finding implies that statistically the same driving mechanism of a nonlinear nature is acting in both HL and LL CME events, and CMEs are intrinsically associated with the source＇s magnetic structure on large spatial scales. Statistically, the HL CMEs are slightly slower than the LL CMEs. For HL and LL CME events respectively, the speed distributions for accelerating and decelerating events are nearly identical and also to a good approximation they can be both fitted with a lognormal distribution, thus supplementing the results obtained by Yurchyshyn et al.展开更多
The cyclical behaviors of sunspots, flares and coronal mass ejections （CMEs） for 54 months from 2008 November to 2013 April after the onset of Solar Cycle （SC） 24 are compared, for the first time, with those of SC...The cyclical behaviors of sunspots, flares and coronal mass ejections （CMEs） for 54 months from 2008 November to 2013 April after the onset of Solar Cycle （SC） 24 are compared, for the first time, with those of SC 23 from 1996 November to 2001 April. The results are summarized below. （i） During the maximum phase, the number of sunspots in SC 24 is significantly smaller than that for SC 23 and the number of flares in SC 24 is comparable to that of SC 23. （ii） The number of CMEs in SC 24 is larger than that in SC 23 and the speed of CMEs in SC 24 is smaller than that of SC 23 during the maximum phase. We individually survey all the CMEs （1647 CMEs） from 2010 June to 2011 June. A total of 161 CMEs associated with so- lar surface activity events can be identified. About 45% of CMEs are associated with quiescent prominence eruptions, 27% of CMEs only with solar flares, 19% of CMEs with both active-region prominence eruptions and solar flares, and 9% of CMEs only with active-region prominence eruptions. Comparing the association of the CMEs and their source regions in SC 24 with that in SC 23, we notice that the characteristics of source regions for CMEs during SC 24 may be different from those of SC 23.展开更多
Major solar eruptions （flares, coronal mass ejections （CMEs） and solar energetic particles （SEPs）） strongly influence geospace and space weather. Currently, the mechanism of their influence on space weather is n...Major solar eruptions （flares, coronal mass ejections （CMEs） and solar energetic particles （SEPs）） strongly influence geospace and space weather. Currently, the mechanism of their influence on space weather is not well understood and requires a detailed study of the energetic relationship among these eruptive phenomena. From this perspective, we investigate 30 flares （observed by RHESSI）, followed by weak to strong geomagnetic storms. Spectral analysis of these flares suggests a new power-law relationship （r - 0.79） between the hard X-ray （HXR） spectral index （before flarepeak） and linear speed of the associated CME observed by LASCO/SOHO. For 12 flares which were followed by SEP enhancement near Earth, HXR and SEP spectral analysis reveals a new scaling law （r - 0.9） between the hardest X-ray flare spectrum and the hardest SEP spectrum. Furthermore, a strong correlation is obtained between the linear speed of the CME and the hardest spectrum of the corresponding SEP event （r - 0.96）. We propose that the potentially geoeffective flare and associated CME and SEP are well-connected through a possible feedback mechanism, and should be regarded within the framework of a solar eruption. Owing to their space weather effects, these new results will help improve our current understanding of the Sun-Earth relationship, which is a major goal of research programs in heliophysics.展开更多
Coronal mass ejection （CME） velocities have been studied over recent decades. We present a statistical analysis of the relationship between CME velocities and X-ray fluxes of the associated flares. We study two type...Coronal mass ejection （CME） velocities have been studied over recent decades. We present a statistical analysis of the relationship between CME velocities and X-ray fluxes of the associated flares. We study two types of CMEs. One is the FL type associated only with flares, while the other is the intermediate type associated with both filament eruptions and flares. It is found that the velocities of the FL type CMEs are strongly correlated with both the peak and the time-integrated X-ray fluxes of the associated flares. However, the correlations between the intermediate type CME velocities and the corre- sponding two parameters are poor. It is also found that the correlation between the CME velocities and the peak X-ray fluxes is stronger than that between the CME velocities and the time-integrated X-ray fluxes of the associated flares.展开更多
太阳高能粒子事件常伴随太阳耀斑和日冕物质抛射事件(Coronal Mass Ejections,CME)出现,由于太阳高能粒子事件的关键因素是双CME的相互作用,利用SOHO卫星观测的高能粒子强度、耀斑强度以及CME的相对高度与时间,通过高度与时间拟合得到...太阳高能粒子事件常伴随太阳耀斑和日冕物质抛射事件(Coronal Mass Ejections,CME)出现,由于太阳高能粒子事件的关键因素是双CME的相互作用,利用SOHO卫星观测的高能粒子强度、耀斑强度以及CME的相对高度与时间,通过高度与时间拟合得到的速度,分析了2001年4月15日和2005年1月20日的太阳高能粒子事件强度与相关双CME事件的关系,发现这两个太阳高能粒子事件中E≥10 MeV质子的强度与双CME事件无关.因此在这两次太阳高能粒子事件早期,E≥10 MeV质子的强度只与相关太阳耀斑和CME有关.展开更多
基金funded by the National Basic Research Program of China (973 Program,Grants 2012CB957801 and 2014CB744203)the National Natural Science Foundation of China (Grant Nos.41074132,41274193,41474166,41304144,11303017 and 11533005)the National Standard Research Program (Grant 200710123)
文摘To investigate the dependence of large gradual solar energetic particle（SEP） events on the associated flares and coronal mass ejections（CMEs）, the correlation coefficients（CCs） between peak intensities of E 〉 10 MeV（I10）, E 〉 30 MeV（I30） and E 〉 50 MeV（I50） protons and soft X-ray（SXR） emission of associated flares and the speeds of associated CMEs in the three longitudinal areas W0–W39, W40–W70（hereafter the well connected region） and W71–W90 have been calculated.Classical correlation analysis shows that CCs between SXR emission and peak intensities of SEP events always reach their largest value in the well connected region and then decline dramatically in the longitudinal area outside the well connected region, suggesting that they may contribute to the production of SEPs in large SEP events. Both classical and partial correlation analyses show that SXR fluence is a better parameter describing the relationship between flares and SEP events. For large SEP events with source location in the well connected region, the CCs between SXR fluence and I10, I30 and I50 are0.58±0.12, 0.80±0.06 and 0.83±0.06 respectively, while the CCs between CME speed and I10, I30 and I50 are 0.56±0.12, 0.52±0.13 and 0.48±0.13 respectively. The partial correlation analyses show that in the well connected region, both CME shock and SXR fluence can significantly affect I10, but SXR peak flux makes no additional contribution. For E 〉 30 MeV protons with source location in the well connected region, only SXR fluence can significantly affect I30, and the CME shock makes a small contribution to I30, but SXR peak flux makes no additional contribution. For E 〉 50 MeV protons with source location in the well connected region, only SXR fluence can significantly affect I50, but both CME shock and SXR peak flux make no additional contribution. We conclude that these findings provide statistical evidence that for SEP events with source locations in the well connected region, a CME shock is only an effective accelerator for E 〈 30 MeV protons. However, flares are not only effective accelerators for E 〈 30 MeV protons, but also for E 〉 30 MeV protons, and E 〉 30 MeV protons may be mainly accelerated by concurrent flares.
基金Supported by the National Natural Science Foundation of China.
文摘Sympathetic coronal mass ejections (CMEs) usually occur in different active regions connected by interconnecting magnetic loops, while homologous CMEs occur within the same active region with an almost the same background magnetic field, and so are similar in shapes. Two sympathetic CMEs erupted within 3 hours on 2002 May 22, originating from the same active region, AR 9948. Their multi-wavelength data were collected and analyzed. It is suggested that emerging flux triggered the occurrence of the first CME and the corresponding flare, the reconnection inflow of which in turn triggered the eruption of the second CME. Based on the fact that the two sympathetic CMEs have many similarities, in their shapes, their low-lying dimming areas, etc., we tentatively propose, for the first time, the phenomenon of sympathetic homologous CMEs.
基金jointly funded by the National Basic Research Program of China (973 Program, Grants 2012CB957801 and 2014CB744203)the National Natural Science Foundation of China (Grants 41074132, 41274193, 41474166, 41304144, 11303017 and 11533005)the National Standard Research Program (Grant 200710123)
文摘To investigate the possible solar source of high-energy protons, correlation coefficients between the peak intensities of E ≥ 100 MeV protons, I100, and the peak flux and fluence of solar soft X-ray（SXR） emission, and coronal mass ejection（CME） linear speed in the three longitudinal areas W0-W39, W40-W70 and W71-W90 have been calculated respectively. Classical correlation analysis shows that the correlation coefficients between CME speeds and I100 in the three longitudinal areas are0.28±0.21, 0.35±0.21 and 0.04±0.30 respectively. The classical correlation coefficients between I100 and SXR peak flux in the three longitudinal areas are 0.48±0.17, 0.72±0.13 and 0.02±0.30 respectively, while the correlation coefficients between I100 and SXR fluence in the three longitudinal areas are 0.25±0.21, 0.84±0.07 and 0.10±0.30 respectively. Partial correlation analysis shows that for solar proton events with source location in the well connected region（W40-W70）, only SXR fluence can significantly affect the peak intensity of E ≥ 100 MeV protons, but SXR peak flux has little influence on the peak intensities of E ≥ 100 MeV protons; moreover, CME speed has no influence on the peak intensities of E ≥ 100 MeV protons. We conclude that these findings provide statistical evidence that E ≥ 100 MeV protons may be mainly accelerated by concurrent flares.
基金partly supported by the National Natural Science Foundation of China(Grant Nos.41304135,41574172,41374177 and 41125016)the CMA(Grant GYHY201106011)the Specialized Research Fund for State Key Laboratories of China
文摘Recently, S. W. Kahler studied the timescales of solar energetic particle （SEP） events asso- ciated with coronal mass ejections （CMEs） from analysis of spacecraft data. They obtained different timescales for SEP events, such as TO, the onset time from CME launch to SEP onset, TR, the rise time from onset to half the peak intensity （0.5/p）, and TD, the duration of the SEP intensity above 0.5Ip. In this work, we solve the transport equation for SEPs considering interplanetary coronal mass ejection （ICME） shocks as energetic particle sources. With our modeling assumptions, our simulations show similar results to Kahler＇s analysis of spacecraft data, that the weighted average of TD increases with both CME speed and width. Moreover, from our simulation results, we suggest TD is directly dependent on CME speed, but not dependent on CME width, which were not found in the analysis of observational data.
基金the National Natural Science Foundation of China
文摘We analyzed the speed （v） distributions of 11584 coronal mass ejections （CMEs） observed by the Large Angle and Spectrometric Coronagraph Experiment on board the Solar and Heliospheric Observatory （SOHO/LASCO） in cycle 23 from 1996 to 2006. We find that the speed distributions for high-latitude （HL） and low-latitude （LL） CME events are nearly identical and to a good approximation they can be fitted with a lognormal distribution. This finding implies that statistically the same driving mechanism of a nonlinear nature is acting in both HL and LL CME events, and CMEs are intrinsically associated with the source＇s magnetic structure on large spatial scales. Statistically, the HL CMEs are slightly slower than the LL CMEs. For HL and LL CME events respectively, the speed distributions for accelerating and decelerating events are nearly identical and also to a good approximation they can be both fitted with a lognormal distribution, thus supplementing the results obtained by Yurchyshyn et al.
基金Supported by the National Natural Science Foundation of China
文摘The cyclical behaviors of sunspots, flares and coronal mass ejections （CMEs） for 54 months from 2008 November to 2013 April after the onset of Solar Cycle （SC） 24 are compared, for the first time, with those of SC 23 from 1996 November to 2001 April. The results are summarized below. （i） During the maximum phase, the number of sunspots in SC 24 is significantly smaller than that for SC 23 and the number of flares in SC 24 is comparable to that of SC 23. （ii） The number of CMEs in SC 24 is larger than that in SC 23 and the speed of CMEs in SC 24 is smaller than that of SC 23 during the maximum phase. We individually survey all the CMEs （1647 CMEs） from 2010 June to 2011 June. A total of 161 CMEs associated with so- lar surface activity events can be identified. About 45% of CMEs are associated with quiescent prominence eruptions, 27% of CMEs only with solar flares, 19% of CMEs with both active-region prominence eruptions and solar flares, and 9% of CMEs only with active-region prominence eruptions. Comparing the association of the CMEs and their source regions in SC 24 with that in SC 23, we notice that the characteristics of source regions for CMEs during SC 24 may be different from those of SC 23.
基金the CAWSES-India Program, supported by the Indian Space Research Organization (ISRO), Dept. of Space, Govt. of India
文摘Major solar eruptions （flares, coronal mass ejections （CMEs） and solar energetic particles （SEPs）） strongly influence geospace and space weather. Currently, the mechanism of their influence on space weather is not well understood and requires a detailed study of the energetic relationship among these eruptive phenomena. From this perspective, we investigate 30 flares （observed by RHESSI）, followed by weak to strong geomagnetic storms. Spectral analysis of these flares suggests a new power-law relationship （r - 0.79） between the hard X-ray （HXR） spectral index （before flarepeak） and linear speed of the associated CME observed by LASCO/SOHO. For 12 flares which were followed by SEP enhancement near Earth, HXR and SEP spectral analysis reveals a new scaling law （r - 0.9） between the hardest X-ray flare spectrum and the hardest SEP spectrum. Furthermore, a strong correlation is obtained between the linear speed of the CME and the hardest spectrum of the corresponding SEP event （r - 0.96）. We propose that the potentially geoeffective flare and associated CME and SEP are well-connected through a possible feedback mechanism, and should be regarded within the framework of a solar eruption. Owing to their space weather effects, these new results will help improve our current understanding of the Sun-Earth relationship, which is a major goal of research programs in heliophysics.
基金the State Key Laboratory of Space Weather for its support to the Open Research Program
文摘Coronal mass ejection （CME） velocities have been studied over recent decades. We present a statistical analysis of the relationship between CME velocities and X-ray fluxes of the associated flares. We study two types of CMEs. One is the FL type associated only with flares, while the other is the intermediate type associated with both filament eruptions and flares. It is found that the velocities of the FL type CMEs are strongly correlated with both the peak and the time-integrated X-ray fluxes of the associated flares. However, the correlations between the intermediate type CME velocities and the corre- sponding two parameters are poor. It is also found that the correlation between the CME velocities and the peak X-ray fluxes is stronger than that between the CME velocities and the time-integrated X-ray fluxes of the associated flares.
文摘太阳高能粒子事件常伴随太阳耀斑和日冕物质抛射事件(Coronal Mass Ejections,CME)出现,由于太阳高能粒子事件的关键因素是双CME的相互作用,利用SOHO卫星观测的高能粒子强度、耀斑强度以及CME的相对高度与时间,通过高度与时间拟合得到的速度,分析了2001年4月15日和2005年1月20日的太阳高能粒子事件强度与相关双CME事件的关系,发现这两个太阳高能粒子事件中E≥10 MeV质子的强度与双CME事件无关.因此在这两次太阳高能粒子事件早期,E≥10 MeV质子的强度只与相关太阳耀斑和CME有关.
