基于SAMPEX卫星观测的南大西洋异常区高能质子动态分布特征

Dynamic Distribution Features of Energetic Proton in South Atlantic Anomaly Based on the Observation of SAMPEX

利用SAMPEX卫星1992年7月至2004年6月1927 MeV高能质子数据对南大西洋异常区的分布特征进行研究,发现南大西洋异常区高能质子分布随高度及F10.7的变化十分显著.在540士25 km高度上,地磁较为平静时期南大西洋异常区高能质子微分通量随着F10.7的增大而减小,同时在F10.7≥115 sfu时减小趋势较为平缓.对中等及以上磁暴进行统计分析发现,磁暴期间南大西洋异常区高能质子微分通量和SYM-H指数的绝对值存在明显的反相关关系,且地磁暴对南大西洋异常区高能质子微分通量存在明显的持续影响效应.磁暴发生期间高能质子微分通量明显减少.磁暴恢复相及其之后高能质子微分通量呈现较为显著的恢复过程.

After lots of experiments by using 19~27 MeV differential energetic proton data based on the observation of SAMPEX from July of 1992 to June of 2004,it is found that the change of F_(10.7) and altitude have a great influence on the distribution of differential energetic proton flux in South Atlantic Anomaly.During the geomagnetic quiet time at 540±25km altitude,the energetic proton flux in South Atlantic Anomaly decreased with the increasing of F_(10.7_,and the variation trend was flat when F_(10.7)≥ 115 sfu.It is found that there was obviously an anti-correlation between the absolute value of SYM-H and the differential energetic proton flux in South Atlantic Anomaly for storms with SYM-H <-50,and also there was a lasting effect on differential energetic proton flux in South Atlantic Anomaly.In addition,the proton flux could be significantly reduced in South Atlantic Anomaly during the main phase,while the proton flux showed a substantial resuming trend in the recovery phase of geomagnetic storms.