NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States); University Corporation for Atmospheric Research, Boulder, CO (United States); Vikram Sarabhai Space Centre, Thiruvananthapuram (India)
NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States)
National Oceanic and Atmospheric Administration (NOAA), Boulder, CO (United States)
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States); Univ. of Maryland, Baltimore, MD (United States)
NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States); The Catholic Univ. of America, Washington, DC (United States)
Fast reverse shocks (FRSs) cause the magnetosphere to expand, by contrast to the well-known compressions caused by the impact of fast forward shocks (FFS). Usually, FFSs are more geoeffective than FRSs, and consequently the inner magnetosphere dynamic responses to both shock types can be quite different. In this study, we investigate for the first time the radiation belt response to an FRS impact using multi-satellite observations and numerical simulations. Spacecraft on the dayside observed decreases in magnetic field strength and energetic (~40–475 keV) particle fluxes. Timing analysis shows that the magnetic field signature propagated from the dayside to the nightside magnetosphere. Particles with different energies vary simultaneously at each spacecraft, implying a non-dispersive particle response to the shock. Spacecraft located at lower L-shells did not record any significant signatures. The observations indicate a local time dependence of the response associated with the shock inclination, with the clearest signatures being observed in the dusk–midnight sector. Simulations underestimate the amplitude of the magnetic field variations observed on the nightside. The observed decreases in the electron intensities result from a combination of radial gradient and adiabatic effects. The radial gradients in the spectral index appear to be the dominant contributor to the observed variations of electrons seen on the dayside (near noon and dusk) and on the nightside (near midnight). This work shows that even an FRS can affect the radiation belts significantly and provides an opportunity to understand their dynamic response to a sudden expansion of the magnetosphere.
Bhaskar, Ankush, et al. "Radiation Belt Response to Fast Reverse Shock at Geosynchronous Orbit." The Astrophysical Journal, vol. 910, no. 2, Apr. 2021. https://doi.org/10.3847/1538-4357/abd702
Bhaskar, Ankush, Sibeck, David, Kanekal, Shrikanth G., Singer, Howard J., Reeves, Geoffrey, Oliveira, Denny M., Kang, Suk-Bin, & Komar, Colin (2021). Radiation Belt Response to Fast Reverse Shock at Geosynchronous Orbit. The Astrophysical Journal, 910(2). https://doi.org/10.3847/1538-4357/abd702
Bhaskar, Ankush, Sibeck, David, Kanekal, Shrikanth G., et al., "Radiation Belt Response to Fast Reverse Shock at Geosynchronous Orbit," The Astrophysical Journal 910, no. 2 (2021), https://doi.org/10.3847/1538-4357/abd702
@article{osti_1832373,
author = {Bhaskar, Ankush and Sibeck, David and Kanekal, Shrikanth G. and Singer, Howard J. and Reeves, Geoffrey and Oliveira, Denny M. and Kang, Suk-Bin and Komar, Colin},
title = {Radiation Belt Response to Fast Reverse Shock at Geosynchronous Orbit},
annote = {Fast reverse shocks (FRSs) cause the magnetosphere to expand, by contrast to the well-known compressions caused by the impact of fast forward shocks (FFS). Usually, FFSs are more geoeffective than FRSs, and consequently the inner magnetosphere dynamic responses to both shock types can be quite different. In this study, we investigate for the first time the radiation belt response to an FRS impact using multi-satellite observations and numerical simulations. Spacecraft on the dayside observed decreases in magnetic field strength and energetic (~40–475 keV) particle fluxes. Timing analysis shows that the magnetic field signature propagated from the dayside to the nightside magnetosphere. Particles with different energies vary simultaneously at each spacecraft, implying a non-dispersive particle response to the shock. Spacecraft located at lower L-shells did not record any significant signatures. The observations indicate a local time dependence of the response associated with the shock inclination, with the clearest signatures being observed in the dusk–midnight sector. Simulations underestimate the amplitude of the magnetic field variations observed on the nightside. The observed decreases in the electron intensities result from a combination of radial gradient and adiabatic effects. The radial gradients in the spectral index appear to be the dominant contributor to the observed variations of electrons seen on the dayside (near noon and dusk) and on the nightside (near midnight). This work shows that even an FRS can affect the radiation belts significantly and provides an opportunity to understand their dynamic response to a sudden expansion of the magnetosphere.},
doi = {10.3847/1538-4357/abd702},
url = {https://www.osti.gov/biblio/1832373},
journal = {The Astrophysical Journal},
issn = {ISSN 0004-637X},
number = {2},
volume = {910},
place = {United States},
publisher = {IOP Publishing},
year = {2021},
month = {04}}