Variations in cutoff latitude during selected solar energetic proton events
Variations in cutoff latitude during selected solar energetic proton events
复制标题
选定的太阳高能质子事件期间截止纬度的变化
DOI：
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发表时间：
2005
期刊：
影响因子：
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通讯作者：
B. Bromage
中科院分区：
文献类型：
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作者：
M. J. Birch;J. Hargreaves;J. Hargreaves;A. Senior;B. Bromage
在2001年的三次太阳质子事件期间，从极轨道环境卫星POES 15和POES 16获得了质子计数率测量值。根据这些数据，在四个当地时间确定了质子通量截止的不变纬度。卫星在当地时间大约0300、0830、1230和1800时对北方极冠的边缘进行采样，覆盖清晨、上午晚些时候、中午和晚上。在4月2日的事件中，35-70 MeV质子的截止纬度几乎是恒定的，随当地时间的变化不超过1.5°。日冕物质抛射的影响发生在9月24日和11月4日的事件期间，其影响是使截止纬度降低5°至8°。截止纬度向赤道方向的位移与磁暴指数（Dst和SYM-H）有很强的相关性。定义了截止纬度预报公式。使用Tsyganenko（2002）磁层模型进行的模拟与平静条件和弱扰动下的观测结果在2σ内一致。
Proton count rate measurements were obtained from the polar orbiting environmental satellites POES15 and POES16 during three solar proton events in 2001. From these data the invariant latitude of the cutoff in proton flux was determined at four local times. The satellites sample the edge of the northern polar cap at approximately 0300, 0830, 1230, and 1800 hours local time, covering the early morning, late morning, noon, and evening. During the event of 2 April the cutoff latitude for 35–70 MeV protons was almost constant, showing no more than 1.5° variation with local time. CME impacts occurred during the 24 September and 4 November events, the effects of which were to reduce the cutoff latitudes by between 5° and 8°. The equatorward displacement of the cutoff latitude was found to be strongly correlated with the magnetic storm indices (D st and SYM-H). Cutoff latitude prediction formulae are defined. Simulations using the Tsyganenko (2002) model of the magnetosphere are consistent with observations to within 2σ during quiet conditions and weak disturbances.