EMIC wave parameterization in the long‐term VERB code simulation

Drozdov, Alexander; Shprits, Y. Y.; Usanova, Maria; Aseev, Nikita; Kellerman, Adam; Zhu, Hui

doi:10.1002/2017ja024389

Cited by 61 publications

(111 citation statements)

References 64 publications

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“…Consequently, at L * < 4 during the flux dropout interval there appears to be some evidence for other electron loss processes which may be occurring. Additional loss processes could be active there and scatter electrons into the atmosphere at L * < 4 during the March 2015 storm, such as electron resonance with electro‐magnetic ion cyclotron (EMIC) waves (see e.g., Drozdov et al, and Ukhorskiy et al, ). Alternatively, the additional loss may also result from resonant wave‐particle interactions with small scale size kinetic Alfvén waves which are not included in our simulations (see Chaston et al, ).…”

Section: Resultsmentioning

confidence: 99%

“…There is no need to include any additional artificial fast electron loss, which might result from a wave-particle interaction with kinetic Alfvén waves causing loss to the magnetopause (see Chaston et al, 2017) or with EMIC waves causing loss to the atmosphere (see e.g. Drozdov et al, 2017). S.] but with a short time interval of artificial loss with τ = 1 hr included at L* < 3.5, presenting additional fast loss.…”

Section: March 2015 Storm: Improved Simulation Incorporating Additionmentioning

confidence: 99%

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Rapid Outer Radiation Belt Flux Dropouts and Fast Acceleration During the March 2015 and 2013 Storms: The Role of Ultra‐Low Frequency Wave Transport From a Dynamic Outer Boundary

et al. 2020

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We present simulations of the outer radiation belt electron flux during the March 2015 and 2013 storms using a radial diffusion model. Despite differences in disturbance short‐time intensity between the two storms, the response of the ultra‐relativistic electrons in the outer radiation belt was remarkably similar, both showing a sudden drop in the electron flux followed by a rapid enhancement in the outer belt flux to levels over an order of magnitude higher than those observed during the pre‐storm interval. Simulations of the ultra‐relativistic electron flux during the March 2015 storm show that outward radial diffusion can explain the flux dropout down to L*~4. However, in order to reproduce, the observed flux dropout at L* < 4 requires the addition of a loss process characterized by an electron lifetime of around 1 hr operating below L*~3.5 during the flux dropout interval. Nonetheless, during the pre‐storm and recovery phase of both storms, the radial diffusion simulation reproduces the observed flux dynamics. For the March 2013 storm, the flux dropout across all L‐shells is reproduced by outward radial diffusion activity alone. However, during the flux enhancement interval at relativistic energies, there is evidence of a growing local peak in the electron phase space density at L*~3.8, consistent with local acceleration such as by very low frequency chorus waves. Overall, the simulation results for both storms can accurately reproduce the observed electron flux only when event specific radial diffusion coefficients are used, instead of the empirical diffusion coefficients derived from ultra‐low frequency wave statistics.

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Section: Resultsmentioning

confidence: 99%

Section: March 2015 Storm: Improved Simulation Incorporating Additionmentioning

confidence: 99%

Rapid Outer Radiation Belt Flux Dropouts and Fast Acceleration During the March 2015 and 2013 Storms: The Role of Ultra‐Low Frequency Wave Transport From a Dynamic Outer Boundary

et al. 2020

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“…Their relevance to the radiation belt dynamics has been evaluated in earlier works, based either on observations or model simulations (Albert & Young, 2005;Albert et al, 2009;Drozdov et al, 2015Drozdov et al, , 2017Shprits et al, 2006Shprits et al, , 2008Shprits et al, , 2016Shprits et al, , 2017Subbotin et al, 2010;Turner, Angelopoulos, Morley, et al, 2014;Usanova et al, 2014;Xiang et al, 2017;Xiao et al, 2010;Yu et al, 2013). Their relevance to the radiation belt dynamics has been evaluated in earlier works, based either on observations or model simulations (Albert & Young, 2005;Albert et al, 2009;Drozdov et al, 2015Drozdov et al, , 2017Shprits et al, 2006Shprits et al, , 2008Shprits et al, , 2016Shprits et al, , 2017Subbotin et al, 2010;Turner, Angelopoulos, Morley, et al, 2014;Usanova et al, 2014;Xiang et al, 2017;Xiao et al, 2010;Yu et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

“…The bounce-averaged diffusion coefficients for hiss and dayside and nightside chorus waves are computed using the Full Diffusion Code ). In accordance with Drozdov et al (2017), EMIC waves are included in the simulation when the solar wind dynamic pressure is greater than or equal to 3 nPa. The spectral properties from Meredith et al (2014) are used to calculate diffusion coefficients for helium band EMIC waves.…”

Section: Introductionmentioning

confidence: 99%

Identifying Radiation Belt Electron Source and Loss Processes by Assimilating Spacecraft Data in a Three‐Dimensional Diffusion Model

et al. 2020

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Data assimilation aims to blend incomplete and inaccurate data with physics-based dynamical models. In the Earth's radiation belts, it is used to reconstruct electron phase space density, and it has become an increasingly important tool in validating our current understanding of radiation belt dynamics, identifying new physical processes, and predicting the near-Earth hazardous radiation environment. In this study, we perform reanalysis of the sparse measurements from four spacecraft using the three-dimensional Versatile Electron Radiation Belt diffusion model and a split-operator Kalman filter over a 6-month period from 1 October 2012 to 1 April 2013. In comparison to previous works, our 3-D model accounts for more physical processes, namely, mixed pitch angle-energy diffusion, scattering by Electromagnetic Ion Cyclotron waves, and magnetopause shadowing. We describe how data assimilation, by means of the innovation vector, can be used to account for missing physics in the model. We use this method to identify the radial distances from the Earth and the geomagnetic conditions where our model is inconsistent with the measured phase space density for different values of the invariants and K. As a result, the Kalman filter adjusts the predictions in order to match the observations, and we interpret this as evidence of where and when additional source or loss processes are active. The current work demonstrates that 3-D data assimilation provides a comprehensive picture of the radiation belt electrons and is a crucial step toward performing reanalysis using measurements from ongoing and future missions.

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“…Orlova et al , 2016Agapitov et al 2015;Spasojevic et al 2015;Drozodov et al 2017). Still, these models cannot always predict the outcome in event-specific instances, since less is known about which loss mechanism may play a larger role at a given time.…”

Section: Loss Mechanismsmentioning

confidence: 99%

Space Weather Effects in the Earth’s Radiation Belts

et al. 2017

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The first major scientific discovery of the Space Age was that the Earth is enshrouded in toroids, or belts, of very high-energy magnetically trapped charged particles. Early observations of the radiation environment clearly indicated that the Van Allen belts could be delineated into an inner zone dominated by high-energy protons and an outer zone dominated by high-energy electrons. The energy distribution, spatial extent and particle species makeup of the Van Allen belts has been subsequently explored by several space missions. Recent observations by the NASA dual-spacecraft Van Allen Probes mission have revealed many novel properties of the radiation belts, especially for electrons at highly relativistic and ultra-relativistic kinetic energies. In this review we summarize the space weather impacts of the radiation belts. We demonstrate that many remarkable features of energetic particle changes are driven by strong solar and solar wind forcings. Recent comprehensive data show broadly and in many ways how high energy particles are accelerated, transported, and lost in the magnetosphere due to interplanetary shock wave interactions, coronal mass ejection impacts, and high-speed solar wind streams. We also discuss how radiation belt particles are intimately tied to other parts of the geospace system through atmosphere, ionosphere, and plasmasphere coupling. The new data have in many ways rewritten the textbooks about the radiation belts as a key space weather threat to human technological systems.

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EMIC wave parameterization in the long‐term VERB code simulation

Cited by 61 publications

References 64 publications

Rapid Outer Radiation Belt Flux Dropouts and Fast Acceleration During the March 2015 and 2013 Storms: The Role of Ultra‐Low Frequency Wave Transport From a Dynamic Outer Boundary

Rapid Outer Radiation Belt Flux Dropouts and Fast Acceleration During the March 2015 and 2013 Storms: The Role of Ultra‐Low Frequency Wave Transport From a Dynamic Outer Boundary

Identifying Radiation Belt Electron Source and Loss Processes by Assimilating Spacecraft Data in a Three‐Dimensional Diffusion Model

Space Weather Effects in the Earth’s Radiation Belts

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