Interplanetary shock can greatly disturb the Earth's magnetosphere and ionosphere, causing the temporal and spatial changes of the magnetic field and plasmas at the geosynchronous orbit. In this paper, we use the ...Interplanetary shock can greatly disturb the Earth's magnetosphere and ionosphere, causing the temporal and spatial changes of the magnetic field and plasmas at the geosynchronous orbit. In this paper, we use the magnetic field data of GOES satellites from 1997 to 2007 and the plasma data of MPA on the LANL satellites from 1997 to 2004 to study the properties of magnetic field and plasma (0.03―45 keV) at the geosynchronous orbit (6.6 RE) within 3 hours before and after the arrival of shock front at the geosynchronous orbit through both case study and superposed epoch analysis. It is found that following the arrival of shock front at the geosynchronous orbit, the magnetic field magnitude, as well as GSM BZ component increases significantly on the dayside (8―16 LT), while the BY component has almost no change before and after shock impacts. In response to the interplanetary shock, the proton becomes much denser with a peak number density of 1.2 cm-3, compared to the typical number density of 0.7 cm-3. The proton temperature increases sharply, predominantly on the dusk and night side. The electron, density increases dramatically on the night side with a peak number density of 2.0 cm-3. The inferred ionospheric O+ density after the interplanetary shock impact reaches the maximum value of 1.2 cm-3 on the dusk side and exhibits the clear dawn-dusk asymmetry. The peak of the anisotropy of proton's temperature is located at the noon sector, and the anisotropy decreases towards the dawn and dusk side. The minimum of temperature anisotropy is on the night side. It is suggested that the electromagnetic ion cyclotron (EMIC) wave and whistler wave can be stimulated by the proton and electron temperature anisotropy respectively. The computed electromagnetic ion cyclotron wave (EMIC) intense on the day side (8―16 LT) with a frequency value of 0.8 Hz, and the wave intensity decreases towards the dawn and dusk side, the minimum value can be found on the night side. The computed electron whistler wave locates on the day side展开更多
Aiming at two intense shock events on October 28 and 29, 2003, this paper presents a two-step method, which combines synoptic analysis of space weather ——“observing” and quantitative prediction ——“palpating”, ...Aiming at two intense shock events on October 28 and 29, 2003, this paper presents a two-step method, which combines synoptic analysis of space weather ——“observing” and quantitative prediction ——“palpating”, and then uses it to test predictions. In the first step of “observing”, on the basis of observations of the solar source surface magnetic field, interplanetary scintillation (IPS) and ACE spacecraft, we find that the propagation of the shocks is asymmetric relative to the normal direction of their solar sources, and the Earth is located near the direction of the fastest speed and the greatest energy of the shocks. As the two fast ejection shock events, the fast explosion of coronal mass of the extremely high temperature, the strong magnetic field, and the high speed background solar wind are also helpful to their rapid propagation. In the second step of “palpating”, we adopt a new membership function of the fast shock events for the ISF method. The predicted results show that for the onset time of the geomagnetic disturbance, the relative errors between the observational and the predicted results are 1.8% and 6.7%; and for the magnetic disturbance magnitude, the relative errors are 4.1% and 3.1%, re- spectively. Furthermore, the comparison among the predicted results of our two-step method with those of five other prevailing methods shows that the two-step method is advantageous. The results tell us that understanding the physical features of shock propagation thoroughly is of great importance in improving the prediction precision.展开更多
We analyzed the properties of the solar wind appeared during November 7–8, 1998. Results show that the spaceship ACE spotted a shock (hereinafter referred to as the first shock) at 07:33 UT, November 7. The sheath ap...We analyzed the properties of the solar wind appeared during November 7–8, 1998. Results show that the spaceship ACE spotted a shock (hereinafter referred to as the first shock) at 07:33 UT, November 7. The sheath appeared from the first shock to 22:00 UT November 7. A magnetic cloud-like (MCL) was observed during the period from 22:00 UT November 7 to 11:50 UT, November 8. Another shock was observed at 04:19 UT, November 8 (the second shock). It is apparent that the second shock has entered the rear part of the MCL (MCL_2), though the former part of the MCL (MCL_1) was not affected by the second shock. The main phase of the geomagnetic storm is split into three steps for the convenience of SYM-H index analysis. Step 1 covers the period from the sudden storm commence (SSC) at 08:15 UT, November 7 to the moment of 22:44 UT, November 7. Step 2 starts from 22:44 UT, November 7 and ends at 04:51 UT, November 8. The last step runs from 04:51 UT, November 8 to 06:21 UT, November 8. Step 2 has played a key role in the main development phase of the geomagnetic storm. Analysis of the solar wind properties associated with the main phase shows that the three steps in the main phase have sheath, MCL_1, and MCL_2 as their respective interplanetary source. Specifically, the sheath is covered by the solar wind data from 07:33 UT to 22:00 UT, November 7, MCL1 by the solar wind data from 22:00 UT, November 7 to 04:19 UT November 8, and MCL_2 by the solar wind data from 04:19 UT to 05:57 UT, November 8. MCL_1 had a strong and long lasting so UTh directed magnetic field, allowing it to play a key role in the development of the main phase. MCL_2 made a much smaller contribution to the main development phase, compared with MCL_1.展开更多
Earth's bow shock is the result of interaction between the supersonic solar wind and Earth's magnetopause. However, data limitations mean the model of the shape and position of the bow shock are based largely ...Earth's bow shock is the result of interaction between the supersonic solar wind and Earth's magnetopause. However, data limitations mean the model of the shape and position of the bow shock are based largely on near-Earth satellite data. The model of the bow shock in the distant magnetotail and other factors that affect the bow shock, such as the interplanetary magnetic field(IMF) B_y, remain unclear. Here, based on the bow shock crossings of ARTEMIS from January 2011 to January 2015, new coefficients of the tail-flaring angle a of the Chao model(one of the most accurate models currently available) were obtained by fitting data from the middle-distance magnetotail(near-lunar orbit, geocentric distance -20R_E>X>-50R_E). In addition, the effects of the IMF B_y on the flaring angle a were analyzed. Our results showed that:(1) the new fitting coefficients of the Chao model in the middle-distance magnetotail are more consistent with the observed results;(2) the tail-flaring angle a of the bow shock increases as the absolute value of the IMF B_y increases. Moreover, positive IMF B_y has a greater effect than negative IMF B_y on flaring angle. These results provide a reference for bow shock modeling that includes the IMF B_y.展开更多
The ultra low frequency (ULF) wave in magnetosphere can act as an important means for solar wind energy inward transmission.This paper quantitatively analyzes the propagation process of the ULF wave triggered by the i...The ultra low frequency (ULF) wave in magnetosphere can act as an important means for solar wind energy inward transmission.This paper quantitatively analyzes the propagation process of the ULF wave triggered by the interplanetary shock propagating from inner magnetosphere equatorial plane along magnetic field lines to the top of the ionosphere and below ionosphere propagating process and establishes a relatively complete magnetosphere-ionosphere-atmosphere propagation model which can be used to study the relationship between the amplitude of the ULF waves triggered by the interplanetary shock wave in magnetospheric space and the magnetic effect caused by the ULF waves.After a comparison with recent observations,we found that: in the event during November 7,2004 that an interplanetary shock wave interacted with the magnetosphere,Cluster satellites observed that electric field fluctuations and the band-pass filtered result of ground stations meridional component had similar characteristics.Comparing with the geomagnetic measurement near the footprints,we found that the electric field disturbance in the magnetosphere spread along the ground magnetic field lines in the form of the ULF waves and changed into geomagnetic disturbance.The result reveals that the ULF wave is in contact with the ground geomagnetic observation.The ULF waves couple with ionized components in ionosphere and spread to the ground in the form of electromagnetic waves.In this research,we believe that the magnetosphere,ionosphere and ground magnetic effects caused by interplanetary shock wave are the same physical phenomena responding in different locations.Based on the overall consideration of entire electromagnetic response to the interplanetary shock wave,we found that the correlation between CLUSTER multi-satellite observation and geomagnetic station observation is due to the ULF wave propagated in magnetosphere-ionosphere-atmosphere system,and we quantitatively interpreted this response process.展开更多
Interplanetary shocks or solar wind pressure pulses have prompted impacts on Earth's magnetospheric and ionospheric environment, especially in causing dynamic changes to the bright aurora in the polar ionosphere. ...Interplanetary shocks or solar wind pressure pulses have prompted impacts on Earth's magnetospheric and ionospheric environment, especially in causing dynamic changes to the bright aurora in the polar ionosphere. The auroral phenomenon associated with shock impingements, referred to as shock aurora, exhibits distinct signatures differing from other geophysical features on the dayside polar ionosphere. Shock aurora provides a direct manifestation of the solar wind–magnetosphere–ionosphere interaction. Imagers onboard satellites can obtain the associated large-scale auroral characteristics during shock impingement on the magnetopause. Therefore, auroral data from satellites are very useful for surveying the comprehensive features of shock aurora and their general evolution. Nonetheless, the ground-based high temporal-spatial resolution all-sky imagers installed at scientific stations play an essential role in revealing medium-and small-scale characteristics of shock aurora. Here, we focus on shock aurora imaging signatures measured by imagers onboard satellites and ground-based all-sky imagers.展开更多
Substorm processes have been studied in detail,and it is well known that interplanetary(IP)shock encountering the terrestrial magnetosphere causes global responses.However,how IP shock compression to the magnetosphere...Substorm processes have been studied in detail,and it is well known that interplanetary(IP)shock encountering the terrestrial magnetosphere causes global responses.However,how IP shock compression to the magnetosphere affects the development of an ongoing substorm remains uninvestigated.Herein,the simultaneous satellite and ground-based auroral evolutions associated with an IP shock impact on the magnetopause during an ongoing substorm on May 7th,2005,were examined.The IMAGE satellite over the Southern Hemisphere captured the global development substorm,which was initiated at 17:38:47 UT.The poleward branch of the nightside auroral oval was fortuitously monitored by an all-sky camera at the Zhongshan Station(-74.5°magnetic latitude,ZHO)in Antarctica.The satellite imager observed continuous brightening and broadening of the nightside auroral oval after the IP shock arrival.The simultaneous ground-based optical aurora measurement displayed the intensification and expansion of a preexisting auroral surge poleward of the aurora oval.The geomagnetic field variations and the instantly increased PC indices indicated an elevated merging rate and enhanced the convection-related DP-2 currents.Therefore,this IP shock transient impact did not significantly change the ongoing development of the substorm,although it meets the magnetospheric precondition hypothesis.展开更多
This paper presents a comparative analysis on the two Solar Proton Events (SPE), which occurred on 14 July 2000 (Bastille Day) and 28 October 2003 (28OCT03) respectively. It is found that although the peak flux of the...This paper presents a comparative analysis on the two Solar Proton Events (SPE), which occurred on 14 July 2000 (Bastille Day) and 28 October 2003 (28OCT03) respectively. It is found that although the peak flux of the latter seemed to be greater than that of the former based on geostationary observations, the maximum intensities of the energetic protons (>10 MeV and 30 MeV) during the Bastille Day event were all higher than those of the 28OCT03 event according to the interplanetary observations. Further analysis indicated that the quantity of the seed particles, which could be accelerated to the energies exceeding 10 and 30 MeV by the Coronal Mass Ejection (CME)-driven shock on 14 July 2000, was far larger than that of the 28OCT03 event. In the Bastille Day case, when the CME approached to the height around 14 R⊙, the CME-driven shock would reach its maximum capacity in accelerating the solar en- ergetic protons (>100 MeV). In contrast, on 28 October 2003, when CME approached to the height about 58R⊙, the CME-driven shock reached its highest potential in accelerating the solar energetic protons of the same category. At this moment, the peak flux (>100 MeV) was about 155 pfu, which was much lower than 355 pfu measured on 14 July 2000. This demonstrated that in the Bastille Day event, the quantity of the seed particles, which could be accelerated to the energy beyond 100 MeV, was significantly larger than its counterpart in the 28OCT03 case. Therefore, the peak flux of an SPE event depends not only on the interplanetary intensity of the solar energetic particles, but also on the velocity of the associated CME-driven shock, and the quantity of the seed particles as well as on the interplanetary magnetic en- vironment. This paper also reveals that the magnetic sheath associated with ICME on 28 October 2003 captured a large number of solar energetic protons, including those having energy greater than 100 MeV.展开更多
Two interplanetary shocks are examined to determine the responses of the magnetic field and plasma in the plasma sheet upon the shock impacts by using TC-1 observational data.The two shocks are observed by WIND on Nov...Two interplanetary shocks are examined to determine the responses of the magnetic field and plasma in the plasma sheet upon the shock impacts by using TC-1 observational data.The two shocks are observed by WIND on November 7,2004.Prior to and after the shock,the IMF is either weakly southward or northward.The responses of the plasma sheet to the two shocks are intense and much similar.When the shock interacts with the magnetosphere,the magnetic field impulsively increases 1-2 min after the geomagnetic field sudden impulse (SI) judged from the Sym-H index change,and the magnetic field line is stretched.On the other hand,all of the ion density,the ion temperature,and the velocity of ion flow in the plasma sheet increase.Interestingly,quasi-periodical oscillations of the ion flow are suddenly enhanced,and the plasma flow is basically perpendicular to the local magnetic field.The responses of the magnetic field and the plasma are nearly simultaneous.The responses in the plasma sheet are probably caused by the lateral compression due to the dynamic pressure enhancement downstream the shock when the shock propagates antisunward in the magnetosheath.展开更多
基金Supported by the National Natural Science Foundation of China (Grant No. 40831061)
文摘Interplanetary shock can greatly disturb the Earth's magnetosphere and ionosphere, causing the temporal and spatial changes of the magnetic field and plasmas at the geosynchronous orbit. In this paper, we use the magnetic field data of GOES satellites from 1997 to 2007 and the plasma data of MPA on the LANL satellites from 1997 to 2004 to study the properties of magnetic field and plasma (0.03―45 keV) at the geosynchronous orbit (6.6 RE) within 3 hours before and after the arrival of shock front at the geosynchronous orbit through both case study and superposed epoch analysis. It is found that following the arrival of shock front at the geosynchronous orbit, the magnetic field magnitude, as well as GSM BZ component increases significantly on the dayside (8―16 LT), while the BY component has almost no change before and after shock impacts. In response to the interplanetary shock, the proton becomes much denser with a peak number density of 1.2 cm-3, compared to the typical number density of 0.7 cm-3. The proton temperature increases sharply, predominantly on the dusk and night side. The electron, density increases dramatically on the night side with a peak number density of 2.0 cm-3. The inferred ionospheric O+ density after the interplanetary shock impact reaches the maximum value of 1.2 cm-3 on the dusk side and exhibits the clear dawn-dusk asymmetry. The peak of the anisotropy of proton's temperature is located at the noon sector, and the anisotropy decreases towards the dawn and dusk side. The minimum of temperature anisotropy is on the night side. It is suggested that the electromagnetic ion cyclotron (EMIC) wave and whistler wave can be stimulated by the proton and electron temperature anisotropy respectively. The computed electromagnetic ion cyclotron wave (EMIC) intense on the day side (8―16 LT) with a frequency value of 0.8 Hz, and the wave intensity decreases towards the dawn and dusk side, the minimum value can be found on the night side. The computed electron whistler wave locates on the day side
基金jointly supported by the National Natural Science Foundation of China(Grant Nos.40536029,40336053 and 40374056)the International Collaboration Research Team Program of the Chinese Academy of Sciences.
文摘Aiming at two intense shock events on October 28 and 29, 2003, this paper presents a two-step method, which combines synoptic analysis of space weather ——“observing” and quantitative prediction ——“palpating”, and then uses it to test predictions. In the first step of “observing”, on the basis of observations of the solar source surface magnetic field, interplanetary scintillation (IPS) and ACE spacecraft, we find that the propagation of the shocks is asymmetric relative to the normal direction of their solar sources, and the Earth is located near the direction of the fastest speed and the greatest energy of the shocks. As the two fast ejection shock events, the fast explosion of coronal mass of the extremely high temperature, the strong magnetic field, and the high speed background solar wind are also helpful to their rapid propagation. In the second step of “palpating”, we adopt a new membership function of the fast shock events for the ISF method. The predicted results show that for the onset time of the geomagnetic disturbance, the relative errors between the observational and the predicted results are 1.8% and 6.7%; and for the magnetic disturbance magnitude, the relative errors are 4.1% and 3.1%, re- spectively. Furthermore, the comparison among the predicted results of our two-step method with those of five other prevailing methods shows that the two-step method is advantageous. The results tell us that understanding the physical features of shock propagation thoroughly is of great importance in improving the prediction precision.
基金supported by National Natural Science Foundation of China (Grant No. 50677020)National High Technology Research and Development Program of China (Grant No. 2009AA12Z150)+2 种基金Science and Technology Diffusion Program of China Meteorological Administration (Grant No.CMATG2007M03)National Standard Program (Grant No. 2007GYB118)Chief Forecaster Program of China Meteorological Administration
文摘We analyzed the properties of the solar wind appeared during November 7–8, 1998. Results show that the spaceship ACE spotted a shock (hereinafter referred to as the first shock) at 07:33 UT, November 7. The sheath appeared from the first shock to 22:00 UT November 7. A magnetic cloud-like (MCL) was observed during the period from 22:00 UT November 7 to 11:50 UT, November 8. Another shock was observed at 04:19 UT, November 8 (the second shock). It is apparent that the second shock has entered the rear part of the MCL (MCL_2), though the former part of the MCL (MCL_1) was not affected by the second shock. The main phase of the geomagnetic storm is split into three steps for the convenience of SYM-H index analysis. Step 1 covers the period from the sudden storm commence (SSC) at 08:15 UT, November 7 to the moment of 22:44 UT, November 7. Step 2 starts from 22:44 UT, November 7 and ends at 04:51 UT, November 8. The last step runs from 04:51 UT, November 8 to 06:21 UT, November 8. Step 2 has played a key role in the main development phase of the geomagnetic storm. Analysis of the solar wind properties associated with the main phase shows that the three steps in the main phase have sheath, MCL_1, and MCL_2 as their respective interplanetary source. Specifically, the sheath is covered by the solar wind data from 07:33 UT to 22:00 UT, November 7, MCL1 by the solar wind data from 22:00 UT, November 7 to 04:19 UT November 8, and MCL_2 by the solar wind data from 04:19 UT to 05:57 UT, November 8. MCL_1 had a strong and long lasting so UTh directed magnetic field, allowing it to play a key role in the development of the main phase. MCL_2 made a much smaller contribution to the main development phase, compared with MCL_1.
基金supported by the National Natural Science Foundation of China(Grant Nos.41322031,41404131,41574157,41031065&41304129)the Specialized Research Fund for State Key Laboratoriesthe Shandong Natural Science Foundation(Grant Nos.2013BSE27132,BS2013HZ001)
文摘Earth's bow shock is the result of interaction between the supersonic solar wind and Earth's magnetopause. However, data limitations mean the model of the shape and position of the bow shock are based largely on near-Earth satellite data. The model of the bow shock in the distant magnetotail and other factors that affect the bow shock, such as the interplanetary magnetic field(IMF) B_y, remain unclear. Here, based on the bow shock crossings of ARTEMIS from January 2011 to January 2015, new coefficients of the tail-flaring angle a of the Chao model(one of the most accurate models currently available) were obtained by fitting data from the middle-distance magnetotail(near-lunar orbit, geocentric distance -20R_E>X>-50R_E). In addition, the effects of the IMF B_y on the flaring angle a were analyzed. Our results showed that:(1) the new fitting coefficients of the Chao model in the middle-distance magnetotail are more consistent with the observed results;(2) the tail-flaring angle a of the bow shock increases as the absolute value of the IMF B_y increases. Moreover, positive IMF B_y has a greater effect than negative IMF B_y on flaring angle. These results provide a reference for bow shock modeling that includes the IMF B_y.
基金supported by the key project of National Natural Science Foundation of China (Grant No. 40831061)the Specialized Research Fund for State Key Laboratories of China
文摘The ultra low frequency (ULF) wave in magnetosphere can act as an important means for solar wind energy inward transmission.This paper quantitatively analyzes the propagation process of the ULF wave triggered by the interplanetary shock propagating from inner magnetosphere equatorial plane along magnetic field lines to the top of the ionosphere and below ionosphere propagating process and establishes a relatively complete magnetosphere-ionosphere-atmosphere propagation model which can be used to study the relationship between the amplitude of the ULF waves triggered by the interplanetary shock wave in magnetospheric space and the magnetic effect caused by the ULF waves.After a comparison with recent observations,we found that: in the event during November 7,2004 that an interplanetary shock wave interacted with the magnetosphere,Cluster satellites observed that electric field fluctuations and the band-pass filtered result of ground stations meridional component had similar characteristics.Comparing with the geomagnetic measurement near the footprints,we found that the electric field disturbance in the magnetosphere spread along the ground magnetic field lines in the form of the ULF waves and changed into geomagnetic disturbance.The result reveals that the ULF wave is in contact with the ground geomagnetic observation.The ULF waves couple with ionized components in ionosphere and spread to the ground in the form of electromagnetic waves.In this research,we believe that the magnetosphere,ionosphere and ground magnetic effects caused by interplanetary shock wave are the same physical phenomena responding in different locations.Based on the overall consideration of entire electromagnetic response to the interplanetary shock wave,we found that the correlation between CLUSTER multi-satellite observation and geomagnetic station observation is due to the ULF wave propagated in magnetosphere-ionosphere-atmosphere system,and we quantitatively interpreted this response process.
基金supported by the NSFC (Grant nos. 41431072, 41674169, 41474146, and 41831072)the International Collaboration Supporting Project by the Chinese Arctic and Antarctic Administration (Grant no. IC201608)+1 种基金the National Key R&D Program of China (Grant no. 2018YFC1407304)the Chinese Meridian Project
文摘Interplanetary shocks or solar wind pressure pulses have prompted impacts on Earth's magnetospheric and ionospheric environment, especially in causing dynamic changes to the bright aurora in the polar ionosphere. The auroral phenomenon associated with shock impingements, referred to as shock aurora, exhibits distinct signatures differing from other geophysical features on the dayside polar ionosphere. Shock aurora provides a direct manifestation of the solar wind–magnetosphere–ionosphere interaction. Imagers onboard satellites can obtain the associated large-scale auroral characteristics during shock impingement on the magnetopause. Therefore, auroral data from satellites are very useful for surveying the comprehensive features of shock aurora and their general evolution. Nonetheless, the ground-based high temporal-spatial resolution all-sky imagers installed at scientific stations play an essential role in revealing medium-and small-scale characteristics of shock aurora. Here, we focus on shock aurora imaging signatures measured by imagers onboard satellites and ground-based all-sky imagers.
基金supported by the National Key R&D Program of China(Grant No.2021YFE0106400)the National Scientific Foundation of China(Grant Nos.42120104003,41974185 and 42130210)+3 种基金Shanghai Science and Technology Innovation Action Plan(Grant Nos.21DZ1206100 and 22ZR1481200)SOA Key Laboratory for Polar Science(Grant No.KP201703)Chinese Meridian ProjectMNR Innovative Youth Talents Program(Grant No.12110600000018003921)。
文摘Substorm processes have been studied in detail,and it is well known that interplanetary(IP)shock encountering the terrestrial magnetosphere causes global responses.However,how IP shock compression to the magnetosphere affects the development of an ongoing substorm remains uninvestigated.Herein,the simultaneous satellite and ground-based auroral evolutions associated with an IP shock impact on the magnetopause during an ongoing substorm on May 7th,2005,were examined.The IMAGE satellite over the Southern Hemisphere captured the global development substorm,which was initiated at 17:38:47 UT.The poleward branch of the nightside auroral oval was fortuitously monitored by an all-sky camera at the Zhongshan Station(-74.5°magnetic latitude,ZHO)in Antarctica.The satellite imager observed continuous brightening and broadening of the nightside auroral oval after the IP shock arrival.The simultaneous ground-based optical aurora measurement displayed the intensification and expansion of a preexisting auroral surge poleward of the aurora oval.The geomagnetic field variations and the instantly increased PC indices indicated an elevated merging rate and enhanced the convection-related DP-2 currents.Therefore,this IP shock transient impact did not significantly change the ongoing development of the substorm,although it meets the magnetospheric precondition hypothesis.
基金Supported by the National Natural Science Foundation of China (Grant Nos. 10373017 & 5067702)
文摘This paper presents a comparative analysis on the two Solar Proton Events (SPE), which occurred on 14 July 2000 (Bastille Day) and 28 October 2003 (28OCT03) respectively. It is found that although the peak flux of the latter seemed to be greater than that of the former based on geostationary observations, the maximum intensities of the energetic protons (>10 MeV and 30 MeV) during the Bastille Day event were all higher than those of the 28OCT03 event according to the interplanetary observations. Further analysis indicated that the quantity of the seed particles, which could be accelerated to the energies exceeding 10 and 30 MeV by the Coronal Mass Ejection (CME)-driven shock on 14 July 2000, was far larger than that of the 28OCT03 event. In the Bastille Day case, when the CME approached to the height around 14 R⊙, the CME-driven shock would reach its maximum capacity in accelerating the solar en- ergetic protons (>100 MeV). In contrast, on 28 October 2003, when CME approached to the height about 58R⊙, the CME-driven shock reached its highest potential in accelerating the solar energetic protons of the same category. At this moment, the peak flux (>100 MeV) was about 155 pfu, which was much lower than 355 pfu measured on 14 July 2000. This demonstrated that in the Bastille Day event, the quantity of the seed particles, which could be accelerated to the energy beyond 100 MeV, was significantly larger than its counterpart in the 28OCT03 case. Therefore, the peak flux of an SPE event depends not only on the interplanetary intensity of the solar energetic particles, but also on the velocity of the associated CME-driven shock, and the quantity of the seed particles as well as on the interplanetary magnetic en- vironment. This paper also reveals that the magnetic sheath associated with ICME on 28 October 2003 captured a large number of solar energetic protons, including those having energy greater than 100 MeV.
基金supported by the National Natural Science Foundation of China (Grant Nos.40804046,40890160 and 40731054)National Basic Research Program of China (Grant No.2006CB806304)the Specialized Research Fund for State Key Laboratories
文摘Two interplanetary shocks are examined to determine the responses of the magnetic field and plasma in the plasma sheet upon the shock impacts by using TC-1 observational data.The two shocks are observed by WIND on November 7,2004.Prior to and after the shock,the IMF is either weakly southward or northward.The responses of the plasma sheet to the two shocks are intense and much similar.When the shock interacts with the magnetosphere,the magnetic field impulsively increases 1-2 min after the geomagnetic field sudden impulse (SI) judged from the Sym-H index change,and the magnetic field line is stretched.On the other hand,all of the ion density,the ion temperature,and the velocity of ion flow in the plasma sheet increase.Interestingly,quasi-periodical oscillations of the ion flow are suddenly enhanced,and the plasma flow is basically perpendicular to the local magnetic field.The responses of the magnetic field and the plasma are nearly simultaneous.The responses in the plasma sheet are probably caused by the lateral compression due to the dynamic pressure enhancement downstream the shock when the shock propagates antisunward in the magnetosheath.
