太阳高能粒子观测特征经向分布统计

基于多卫星联合观测数据,筛选了2006年12月至2017年10月期间122个太阳高能粒子(SEP)事件及其伴随的日冕物质抛射(CME),分析了SEP事件属性随相对经度的变化、与CME属性之间相关性的经向分布以及与Fe/O比值的关联.研究结果显示:低Fe/O类事件的峰值通量Ip通常更高,伴随CME更大,但通量上升速度较慢...

Statistical Research on the Longitudinal Distribution of Detected Properties of Solar Energetic Particles

Using the observations from multi-points spacecraft, e.g., SOHO and STEREO, 122 SEP events and associated CMEs during the 24th solar cycle from December 2006 to October 2017 are selected. The longitudinal distributions of SEP characteristics and their relationship with CMEs properties are analyzed, as well as the relation with the event-integrated Fe/O ratio. Results are shown as follows: Large SEP events usually have a lower Fe/O ratio, while those events with high Fe/O have lower CME velocity, mass and kinetic energy, but have faster flux rising speed. The duration D_u and peak flux I_p of SEP correlate well with the associated CME velocity positively (correlation coefficient, CC: 0.50 and 0.57). Comparing to the events with a high Fe/O ratio, the events with low Fe/O obviously have much higher correlation coefficients for D_u and I_p with CME. The characteristic time T_O and T_R of SEPs generally increases with the raising of relative longitude, while D_u and I_p decrease distinctly with the raising of relative longitude. And the slope K of the SEPs flux enhancing in the onset phase seems to decrease from the east (-90°) to west (90°) relative to the source region. T_O shows a negative correlation with CME velocity, mass and kinetic energy in the magnetic well-connected points, while there is no distinct correlation in other poor-connected points. Meanwhile, T_R has a positive correlation with CME only in the relative longitude range of -30°, +30°]. D_u and I_p have a stronger correlation with CME velocity in the well-connected condition (CC: 0.60 and 0.75 respectively) than others (0.46 and 0.56). The conclusion reveals that the detection of SEP event and its time profile evolution is not only affected by the associated CME, but also controlled by the relative longitude between the magnetic foot point and the solar eruption source, and for the well-connected points, the detectable SEP event has more high intensity and good positive correlation with its associated CME, which is very important for the space weather prediction of SEP events, especially large or extremely large SEP events. Moreover, the SEP event with a high Fe/O ratio seems to become weaker among the relationship with CME, which implies that some facts such as flare acceleration, seed population, and so on, will play important roles during the generation of gradual SEP events associated with CME-driven shock.