Two Wide‐Angle Imaging Neutral‐Atom Spectrometers and Interstellar Boundary Explorer energetic neutral atom imaging of the 5 April 2010 substorm

Abstract

[1] This study is the first to combine energetic neutral atom (ENA) observations from Two Wide-Angle Imaging Neutral-Atom Spectrometers (TWINS) and Interstellar Boundary Explorer (IBEX). Here we examine the arrival of an interplanetary shock and the subsequent geomagnetically effective substorm on 5 April 2010, which was associated with the Galaxy 15 communications satellite anomaly. IBEX shows sharply enhanced ENA emissions immediately upon compression of the dayside magnetosphere at 08:26:17+/À9 s UT. The compression drove a markedly different spectral shape for the dayside emissions, with a strong enhancement at energies >1 keV, which persisted for hours after the shock arrival, consistent with the higher solar wind speed, density, and dynamic pressure ($10 nPa) after the shock. TWINS ENA observations indicate a slower response of the ring current and precipitation of ring current ions as low-altitude emissions $15 min later, with the >50 keV ion precipitation leading the <10 keV precipitation by $20 min. These observations suggest internal magnetospheric processes are occurring after compression of the magnetosphere and before the ring current ions end up in the loss cone and precipitate into the ionosphere. We also compare MHD simulation results with both the TWINS and IBEX ENA observations; while the overall fluxes and distributions of emissions were generally similar, there were significant quantitative differences. Such differences emphasize the complexity of the magnetospheric system and importance of the global perspective for macroscopic magnetospheric studies. Finally, Appendix A documents important details of the TWINS data processing, including improved binning procedures, smoothing of images to a given level of statistical accuracy, and differential background subtraction.

Magnetosphere dynamics during the 14 November 2012 storm inferred from TWINS, AMPERE, Van Allen Probes, and BATS-R-US–CRCM

“…The fact that modeled ring current structures are not as dynamic as those observed by TWINS agrees with previously published results (McComas et al, 2012). From the comparison between the model and TWINS observations we see that the modeled ring current shows much smoother behavior than the TWINS ring current that has both stronger and clearer injection signatures and faster decay.…”

Imaging the development of the cold dense plasma sheet

“…However, no studies have investigated the thickness (i.e., the north-south direction) of the developing CDPS. Regions of the magnetosphere that have been imaged by IBEX include the dayside subsolar region McComas et al, 2012;Ogasawara et al, 2013Ogasawara et al, , 2015, the Earth's magnetospheric cusps [Petrinec et al, 2011], and the plasma sheet [McComas et al, 2011;Dayeh et al, 2015]. [Funsten et al, 2009;Fuselier et al, 2009], image the Earth's magnetosphere.…”

Electron source at the outer boundary of the radiation belts: Storm time case

“…This storm that started on 5 April 2010 was associated with a coronal mass ejection driven shock [Singer et al, 2010] and was investigated previously in several reports [e.g., Connors et al, 2011;McComas et al, 2012;Goldstein et al, 2012aGoldstein et al, , 2012bClilverd et al, 2012].…”