RBSPICE Observations of the March 17, 2015 Solar Storm Jerry W. Manweiler – Fundamental Technologies, LLC, Lawrence, KS J. Douglas Patterson – Fundamental Technologies, LLC, Lawrence, KS Matina Gkioulidou – The Johns Hopkins Applied Physics Laboratory, Laurel, MD Andrew Gerrard – New Jersey Institute of Technology, Newark, NJ Don Mitchell – The Johns Hopkins Applied Physics Laboratory, Laurel, MD Lou Lanzerotti – New Jersey Institute of Technology, Newark, NJ Sasha Ukhorskiy – The Johns Hopkins Applied Physics Laboratory, Laurel, MD
Spacecraft Orbital Configuration Spacecraft B leads A in the orbit and observes the incidence of the storm on March 17, 2015 at approximately 6:26:22 AM. We report on the first five orbits of each spacecraft observing the storm through all phases: onset, substorms, and recovery.
Key Indices (Solar wind, magnetic field, Dst, KP, AP) ACE spacecraft observed the solar storm beginning on March 16, 2015 when the initial shock of the storm was observed by the magnetometer and charged particle instruments. The Earth’s magnetosphere responded soon after with an maximum drop of Dst to a largest negative value of -232 nT occurring after 11 pm at the ACE spacecraft.
RBSPICE A Observations B observes an initial depletion of energetic particles as the shock impacts the magnetopause and the Earth’s magnetic field a nd energetic particles respond. The depletion of particles occurs around apogee (dipole L value ~ 6 R E ). After the onset of the storm, multiple “substorms” are observed in Dst and there is an equivalent reaction in the fields and particles observed by both A and B instruments. The fields show oscillations indicating wave activity and there are multiple injections of energetic particles occurring at all values of L.
RBSPICE A Spectrograms The following panels show the observed energy spectrograms for the RBSPICE A observations before and during the storm. Units are #/(cm 2 -sr-s-KeV) Pitch Angle Spectrograms and Distribution plots Prior to the storm the particle pitch angle distributions are either butterfly like or fully trapped depending upon the L value and the energy. Below are shown pitch angle spectrograms for each energy distribution of the observed protons. After the onset of the storm the pitch angle distributions become chaotic as a function of energy showing that newly injected particles are observed streaming into the compressed fields from both directions. There are observations in both A and B when the pitch angle distributions show asymmetry in the distribution of the particles indicating that the particles are on field lines that are either open or the instrument is observing newly accelerated and injected particles.
RBSPICE A Energy Spectrograms – each box is for a different energy channel
RBSPICE A Pitch Angle Diagrams – specified by orbit and cut (A, B, C, D, E, or G) – see following plots for cut locations
Partial Particle Pressure compared to Magnetic Field Pressure Evaluation of the magnetic field pressure versus the partial particle pressure for just the energetic species observed by RBSPICE shows a very interesting story as the solar storm evolves. Prior to storm onset the field pressure dominates significantly over the energetic particle pressures. Even with initial onset of the storm the field pressure continues to dominate. Only when the highest negative Dst is observed and the storm goes from onset to initial stages of recovery does the energetic particle pressure become relevant to the whole. At the peak of the storm the total energetic particle pressure, calculated only using the parallel component of the sum of the partial pressure for each species, becomes significantly dominant over the magnetic field pressure. The b highest value of the plasma 𝑄 𝑞𝑏𝑠𝑢 ( 𝛾 = 𝑄 𝑔𝑗𝑓𝑚𝑒 ) is observed by RBSPICE B at the peak negative Dst with A again just missing the observation due to the lagging orbit. The left panel of the below plots show the partial particle pressures for each species. The second panel shows the oxygen to helium ratios as pressures and log(flux). The left most panel (each SC) then shows the field pressure versus the total pressure and the plasma b . The right and left plots (each SC) include marker lines identifying when the above pitch angle distribution plots occur in the pressure plot.
RBSPICE B Observations B observes an initial depletion of energetic particles as the shock impacts the magnetopause and the Earth’s magnetic field a nd energetic particles respond. The depletion of particles occurs around apogee (dipole L value ~ 6 R E ). After the onset of the storm, multiple “substorms” are observed in Dst and there is an equivalent reaction in the fields and particles observed by both A and B instruments. The fields show oscillations indicating wave activity and there are multiple injections of energetic particles occurring at all values of L.
RBSPICE B Spectrograms The following panels show the observed energy spectrograms for the RBSPICE B observations before and during the storm. Units are #/(cm 2 -sr-s-KeV) Pitch Angle Spectrograms and Distribution plots Prior to the storm the particle pitch angle distributions are either butterfly like or fully trapped depending upon the L value and the energy. Below are shown pitch angle spectrograms for each energy distribution of the observed protons. After the onset of the storm the pitch angle distributions become chaotic as a function of energy showing that newly injected particles are observed streaming into the compressed fields from both directions. There are observations in both A and B when the pitch angle distributions show asymmetry in the distribution of the particles indicating that the particles are on field lines that are either open or the instrument is observing newly accelerated and injected particles.
RBSPICE B Energy Spectrograms – each box is for a different energy channel
RBSPICE B Pitch Angle Diagrams – specified by orbit and cut (A, B, C, D, E, or G) – see following plots for cut locations
Partial Particle Pressure compared to Magnetic Field Pressure Evaluation of the magnetic field pressure versus the partial particle pressure for just the energetic species observed by RBSPICE shows a very interesting story as the solar storm evolves. Prior to storm onset the field pressure dominates significantly over the energetic particle pressures. Even with initial onset of the storm the field pressure continues to dominate. Only when the highest negative Dst is observed and the storm goes from onset to initial stages of recovery does the energetic particle pressure become relevant to the whole. At the peak of the storm the total energetic particle pressure, calculated only using the parallel component of the sum of the partial pressure for each species, becomes significantly dominant over the magnetic field pressure. The b highest value of the plasma 𝑄 𝑞𝑏𝑠𝑢 ( 𝛾 = 𝑄 𝑔𝑗𝑓𝑚𝑒 ) is observed by RBSPICE B at the peak negative Dst with A again just missing the observation due to the lagging orbit. The left panel of the below plots show the partial particle pressures for each species. The second panel shows the oxygen to helium ratios as pressures and log(flux). The left most panel (each SC) then shows the field pressure versus the total pressure and the plasma b . The right and left plots (each SC) include marker lines identifying when the above pitch angle distribution plots occur in the pressure plot.
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