Browsing by Author "Gershman, D. J."

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Global-Scale Processes and Effects of Magnetic Reconnection on the Geospace Environment
    (Springer Nature, 2024) Fuselier, S. A.; Petrinec, S. M.; Reiff, P. H.; Birn, J.; Baker, D. N.; Cohen, I. J.; Nakamura, R.; Sitnov, M. I.; Stephens, G. K.; Hwang, J.; Lavraud, B.; Moore, T. E.; Trattner, K. J.; Giles, B. L.; Gershman, D. J.; Toledo-Redondo, S.; Eastwood, J. P.
    Recent multi-point measurements, in particular from the Magnetospheric Multiscale (MMS) spacecraft, have advanced the understanding of micro-scale aspects of magnetic reconnection. In addition, the MMS mission, as part of the Heliospheric System Observatory, combined with recent advances in global magnetospheric modeling, have furthered the understanding of meso- and global-scale structure and consequences of reconnection. Magnetic reconnection at the dayside magnetopause and in the magnetotail are the drivers of the global Dungey cycle, a classical picture of global magnetospheric circulation. Some recent advances in the global structure and consequences of reconnection that are addressed here include a detailed understanding of the location and steadiness of reconnection at the dayside magnetopause, the importance of multiple plasma sources in the global circulation, and reconnection consequences in the magnetotail. These advances notwithstanding, there are important questions about global reconnection that remain. These questions focus on how multiple reconnection and reconnection variability fit into and complicate the Dungey Cycle picture of global magnetospheric circulation.
  • Thumbnail Image
    Item
    Temporal, Spatial, and Velocity-Space Variations of Electron Phase Space Density Measurements at the Magnetopause
    (Wiley, 2023) Shuster, J. R.; Gershman, D. J.; Giles, B. L.; Bessho, N.; Sharma, A. S.; Dorelli, J. C.; Uritsky, V.; Schwartz, S. J.; Cassak, P. A.; Denton, R. E.; Chen, L.-J.; Gurram, H.; Ng, J.; Burch, J.; Webster, J.; Torbert, R.; Paterson, W. R.; Schiff, C.; Viñas, A. F.; Avanov, L. A.; Stawarz, J.; Li, T. C.; Liu, Y.-H.; Argall, M. R.; Afshari, A.; Payne, D. S.; Farrugia, C. J.; Verniero, J.; Wilder, F.; Genestreti, K.; da Silva, D. E.
    Temporal, spatial, and velocity-space variations of electron phase space density are measured observationally and compared for the first time using the four magnetospheric multiscale (MMS) spacecraft at Earth's magnetopause. Equipped with these unprecedented spatiotemporal measurements offered by the MMS tetrahedron, we compute each term of the electron Vlasov equation that governs the evolution of collisionless plasmas found throughout the universe. We demonstrate how to use single spacecraft measurements to improve the resolution of the electron pressure gradient that supports nonideal parallel electric fields, and we develop a model to intuit the types of kinetic velocity-space signatures that are observed in the Vlasov equation terms. Furthermore, we discuss how the gradient in velocity-space sheds light on plasma energy conversion mechanisms and wave-particle interactions that occur in fundamental physical processes such as magnetic reconnection and turbulence.