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A New Four-Component L*-dependent Model for Radial Diffusion based on Solar Wind and Magnetospheric Drivers of ULF Waves
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  • Kyle Robert Murphy,
  • Jasmine Kaur Sandhu,
  • I. Jonathan Rae,
  • Thomas Alexander Daggitt,
  • Sarah A Glauert,
  • Richard B. Horne,
  • Clare E. J. Watt,
  • Sarah N Bentley,
  • Adam C Kellerman,
  • Louis Godwin Ozeke,
  • Alexa J. Halford,
  • Sheng Tian,
  • Aaron Breneman,
  • Leonid Olifer,
  • Ian Mann,
  • Vassilis Angelopoulos,
  • John Wygant
Kyle Robert Murphy
Self

Corresponding Author:[email protected]

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Jasmine Kaur Sandhu
Northumbria University
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I. Jonathan Rae
Northumbria University
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Thomas Alexander Daggitt
British Antarctic Survey
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Sarah A Glauert
British Antarctic Survey
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Richard B. Horne
British Antarctic Survey
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Clare E. J. Watt
Northumbria University
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Sarah N Bentley
University of Reading
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Adam C Kellerman
University of California Los Angeles
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Louis Godwin Ozeke
University of Alberta
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Alexa J. Halford
NASA Goddard Space Flight Center
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Sheng Tian
University of California Los Angeles
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Aaron Breneman
NASA Goddard Space Flight Center
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Leonid Olifer
University of Alberta
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Ian Mann
University of Alberta
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Vassilis Angelopoulos
University of California Los Angeles
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John Wygant
University of Minnesota
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Abstract

Waves which couple to energetic electrons are particularly important in space weather, as they drive rapid changes in the topology and intensity of Earth’s outer radiation belt during geomagnetic storms. This includes Ultra Low Frequency (ULF) waves that interact with electrons via radial diffusion which can lead to electron dropouts and rapid acceleration and inward transport of electrons during. In radiation belt simulations, the strength of this interaction is specified by ULF wave radial diffusion coefficients. In this paper we detail the development of new models of electric and magnetic radial diffusion coefficients derived from in-situ observations of the azimuthal electric field and compressional magnetic field. The new models use L* as it accounts for adiabatic changes due to the dynamic magnetic field coupled with an optimized set of four components of solar wind and geomagnetic activity, Bz, V, Pdyn and Sym-H, as independent variables (inputs). These independent variables are known drivers of ULF waves and offer the ability to calculate diffusion coefficients at a higher cadence then existing models based on Kp. We investigate the performance of the new models by characterizing the model residuals as a function of each independent variable and by comparing to existing radial diffusion models during a quiet geomagnetic period and through a geomagnetic storm. We find that the models developed here perform well under varying levels of activity and have a larger slope or steeper gradient as a function of L* as compared to existing models (higher radial diffusion at higher L* values).
27 Jan 2023Submitted to ESS Open Archive
09 Feb 2023Published in ESS Open Archive