Claudepierre S G, O'Brien T P, Looper M D, Blake J B, Fennell J F, Roeder J L, Clemmons J H, Mazur J E, Turner D L, Reeves G D, Spence H E
Space Sciences Department The Aerospace Corporation El Segundo CA USA.
Department of Atmospheric and Oceanic Sciences University of California Los Angeles CA USA.
J Geophys Res Space Phys. 2019 Feb;124(2):934-951. doi: 10.1029/2018JA026349. Epub 2019 Feb 4.
We describe a new, more accurate procedure for estimating and removing inner zone background contamination from Van Allen Probes Magnetic Electron Ion Spectrometer (MagEIS) radiation belt measurements. This new procedure is based on the underlying assumption that the primary source of background contamination in the electron measurements at L shells less than three, energetic inner belt protons, is relatively stable. Since a magnetic spectrometer can readily distinguish between foreground electrons and background signals, we are able to exploit the proton stability to construct a model of the background contamination in each MagEIS detector by only considering times when the measurements are known to be background dominated. We demonstrate, for relativistic electron measurements in the inner zone, that the new technique is a significant improvement upon the routine background corrections that are used in the standard MagEIS data processing, which can "overcorrect" and therefore remove real (but small) electron fluxes. As an example, we show that the previously reported 1-MeV injection into the inner zone that occurred in June of 2015 was distributed more broadly in L and persisted in the inner zone longer than suggested by previous estimates. Such differences can have important implications for both scientific studies and spacecraft engineering applications that make use of MagEIS electron data in the inner zone at relativistic energies. We compare these new results with prior work and present more recent observations that also show a 1-MeV electron injection into the inner zone following the September 2017 interplanetary shock passage.
我们描述了一种新的、更精确的程序，用于从范艾伦探测器磁电子离子光谱仪（MagEIS）的辐射带测量中估计和去除内区背景污染。这一新程序基于这样一个基本假设：在L壳层小于3的电子测量中，背景污染的主要来源——高能内带质子——相对稳定。由于磁谱仪能够轻易区分前景电子和背景信号，我们能够利用质子的稳定性，仅通过考虑测量已知以背景为主的时间段，来构建每个MagEIS探测器中背景污染的模型。对于内区相对论电子测量，我们证明新技术相对于标准MagEIS数据处理中使用的常规背景校正有显著改进，后者可能“过度校正”，从而去除真实（但较小）的电子通量。例如，我们表明，先前报道的2015年6月发生在内区的1兆电子伏特注入，在L值上分布更广，且在内区持续的时间比先前估计的更长。这种差异对于利用相对论能量下内区MagEIS电子数据的科学研究和航天器工程应用都可能有重要影响。我们将这些新结果与先前的工作进行比较，并展示了更新的观测结果，这些结果也表明在2017年9月行星际激波通过后，有一次1兆电子伏特电子注入内区。
