The Impressive Correlation Between Substorm Activity and the Rebuilding of Earth’s Radiation Belts

Jaynes, Allison

The Impressive Correlation Between Substorm Activity and the Rebuilding of Earth’s Radiation Belts

Monday, 5 March 2018: 10:30

Longshot and Bogey (Hotel Quinta da Marinha)

Allison N Jaynes¹, David Malaspina², Veronica Dike³, Daniel N Baker⁴, Xinlin Li², Hong Zhao⁵ and Shrikanth G Kanekal⁶, (1)University of Colorado at Boulder, LASP, Boulder, CO, United States, (2)Univ Colorado, Boulder, CO, United States, (3)University of California Los Angeles, Los Angeles, CA, United States, (4)LASP, University of Colorado at Boulder, Boulder, CO, United States, (5)Laboratory for Atmospheric and Space Physics, Boulder, CO, United States, (6)Heliophysics Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD, United States

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Abstract:

Substorms have long been thought to constitute a crucial mechanism for accelerating medium-energy particles in Earth’s outer radiation belt to relativistic and ultra-relativistic energies. This process involves resonant interaction between seed electrons (10s-100s keV) and VLF chorus waves, which can grow to great intensities from repeated substorm injections consisting of source energy electrons (few-10s keV). Historically, strong enhancements of outer Van Allen belt energetic electrons have been shown to have a clear dependence on a southward interplanetary magnetic field, again indicating a direct relationship to substorm activity. Using data from the REPT instrument onboard the twin Van Allen Probes satellites, we show a clear and repeatable correlation between increases in integrated substorm power (computed from the AE and AL indices) and ultra-relativistic electron flux enhancements. We refer to this new index as the Accumulated Substorm Activity (ASA) index. We also characterize the lag time between AE/AL enhancement and flux increase, which shows the expected dependence on electron energy. With the existing robust models of predicted AE index together with the new ASA index, we can improve prediction of the radiation environment in near-Earth space.