The relationship between dispersive Alfvén waves (DAWs), magnetospheric activity, and O+ ion outflow/energy density is examined using measurements from the Van Allen Probes. We show that correlated DAW activity and O+ outflow/energization is a characteristic feature of the inner magnetosphere during active conditions and during storms persists for several hours over large L-shell and azimuthal ranges of the plasma sheet. Though enhanced during substorm and storm active periods, these correlated features are most intense during geomagnetic storms. Comparisons show a linear relationship between DAW electric (and magnetic) field energy density and outflowing O+ energy. Statistical measurements from a large number of storms also reveal a linear relationship between DAW energy density and gross enhancements in energetic O+ energy densities. These observations support the notion that DAWs play an important role in the energization of O+ ions into and within the inner magnetosphere.
Bibliographical noteFunding Information:
This research was supported by NASA grant NNX17AG69G and Van Allen Probes funding provided under NASA prime contract NAS5-01072, including the EFW investigation (PI: J.R. Wygant, University of Minnesota), the EMFISIS investigation (PI: C.A. Kletzing, University of Iowa) under JHU/APL contract 921647, RBSP-ECT JHU/APL under contract 967399, and RBSP-RBSPICE JHU/APL under contract 937836 to the New Jersey Institute of Technology. Data used are publicly available online (https://rbsp-ect.lanl.gov/data_pub/), https://emfisis.physics.uiowa.edu/, http://www.space.umn.edu/rbspefw-data/, and http://rbspice.ftecs.com/.
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- dispersive Alfven waves
- geomagnetic storms
- inner magnetosphere
- ion outflow
- oxygen ions