A Climatology of Long-Duration High 2-MeV Electron Flux Periods in the Outer Radiation Belt.

Since the advent of the Space Age, the importance of understanding and forecasting relativistic electron fluxes in the Earth's radiation belts has been steadily growing due to the threat that such particles pose to satellite electronics. Here, we provide a model of long-duration periods of high time-integrated 2-MeV electron flux deep inside the outer radiation belt, based on the significant correlation obtained in 2001-2017 between time-integrated electron flux measured by satellites and a measure of the preceding time-integrated homogenized geomagnetic index. We show that this correlation is likely due to a stronger cumulative chorus wave-driven acceleration of relativistic electrons and a stronger cumulative inward radial diffusion of such electrons during periods of higher time-integrated geomagnetic activity.

A Survey of Dense Low Energy Ions in Earth's Outer Magnetosphere: Relation to Solar Wind Dynamic Pressure, IMF, and Magnetospheric Activity.

The properties of cold, dense, low energy ( 150 eV) ions within Earth's magnetosphere between 6 and 14 distance are examined using data sampled by Time History of Events and Macroscale Interactions during Substorms spacecraft during a new low-energy plasma mode that operated from June 2016 to July 2017. These ions are a persistent feature of the magnetosphere during enhanced solar wind dynamic pressure and/or magnetospheric activity. These ions have densities ranging from 0.

Electron Microburst Size Distribution Derived With AeroCube-6.

Microbursts are an impulsive increase of electrons from the radiation belts into the atmosphere and have been directly observed in low Earth orbit and the upper atmosphere. Prior work has estimated that microbursts are capable of rapidly depleting the radiation belt electrons on the order of a day; hence, their role to radiation belt electron losses must be considered. Losses due to microbursts are not well constrained, and more work is necessary to accurately quantify their contribution as a loss process.

Direct Observation of Electron Distributions inside Millisecond Duration Electron Holes.

Despite the importance of millisecond duration spatial structures [chorus wave nonlinearity or time domain structures (TDS)] to plasma dynamics, there have been no direct observations of the generation and interaction of these waves and TDS with electrons at the millisecond timescale required for their understanding. Through superposition of 0.195 ms Magnetospheric Multiscale Satellite electron measurements inside 37 superposed, millisecond duration electron holes, the first observations of electron spectra and pitch angle distributions on a submillisecond timescale have been obtained.

Electrostatic Steepening of Whistler Waves.

We present surprising observations by the NASA Van Allen Probes spacecraft of whistler waves with substantial electric field power at harmonics of the whistler wave fundamental frequency. The wave power at harmonics is due to a nonlinearly steepened whistler electrostatic field that becomes possible in the two-temperature electron plasma due to the whistler wave coupling to the electron-acoustic mode. The simulation and analytical estimates show that the steepening takes a few tens of milliseconds.