The formation of a temporary third radiation belt in the slot region of Earth’s magnetosphere was reported (Baker et al. in Science 340:186-190, 2013a) from the early data of the radiation belt storm probes (RBSP) mission. The cumulative flux of relativistic electrons in L = 3-3.5 for the third radiation belt of that study is calculated here and defined as threshold flux (TF) (10⁵ cm⁻² s⁻¹ sr⁻¹ MeV⁻¹). A catalogue of 133 events during Sep 2012 – Feb 2019 is presented. Events are distributed into, below threshold flux (BTF), of the order of, one hundred and one thousand times the threshold flux, (OTF), (HTF), and (TTF) categories respectively. Finding high 2 MeV flux threshold at L = 3-3.5 is a way to find ideal condition for the possible formation of a third radiation belt, aware that attaining TF does not necessarily mean formation of the third radiation belt. It is found that BTF occurred 29 times and 105 times cumulative flux exceeded TF but TTF occurred very rarely. The effects of large scale solar wind structures (LSSS) and number of main phase Dst dips on BTF-TTF events are also studied. The findings of this study may be helpful for understanding the third radiation belt formation in the slot region of Earth’s magnetosphere.

据报道，从辐射带风暴探测器（RBSP）任务的早期数据来看，在地球磁层的缝隙区域中形成了一条临时的第三条辐射带（Baker等人，科学340：186-190，2013a）。在此计算该研究的第三条辐射带的相对论电子在L = 3-3.5中的累积通量，并将其定义为阈值通量（TF）（10 ⁵ cm ^-2  s ^-1  sr ^-1  MeV ^-1）。提供了2012年9月至2019年2月133个事件的目录。在阈值通量（BTF）以下，事件分别被分配为阈值通量（OTF），（HTF）和（TTF）类别的一百一十倍的数量级。在L = 3-3.5处找到较高的2 MeV通量阈值是找到可能形成第三条辐射带的理想条件的一种方法，要知道达到TF并不一定意味着要形成第三条辐射带。发现BTF发生了超过TF的29倍和105倍的累积通量，但是TTF很少发生。还研究了大型太阳风结构（LSSS）和主相Dst骤降对BTF-TTF事件的影响。这项研究的结果可能有助于理解地球磁层隙区域的第三辐射带形成。