@article{ZhuShpritsSpasojevicetal.2019,
  author    = {Zhu, Hui and Shprits, Yuri Y. and Spasojevic, M. and Drozdov, Alexander Y.},
  title     = {New hiss and chorus waves diffusion coefficient parameterizations from the Van Allen Probes and their effect on long-term relativistic electron radiation-belt VERB simulations},
  series = {Journal of Atmospheric and Solar-Terrestrial Physics},
  volume    = {193},
  journal   = {Journal of Atmospheric and Solar-Terrestrial Physics},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {1364-6826},
  doi       = {10.1016/j.jastp.2019.105090},
  pages     = {13},
  year      = {2019},
  abstract  = {New wave frequency and amplitude models for the nightside and dayside chorus waves are built based on measurements from the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) instrument onboard the Van Allen Probes. The corresponding 3D diffusion coefficients are systematically obtained. Compared with previous commonly-used (typical) parameterizations, the new parameterizations result in differences in diffusion rates that depend on the energy and pitch angle. Furthermore, one-year 3D diffusive simulations are performed using the Versatile Electron Radiation Belt (VERB) code. Both typical and new wave parameterizations simulation results are in a good agreement with observations at 0.9 MeV. However, the new parameterizations for nightside chorus better reproduce the observed electron fluxes. These parameterizations will be incorporated into future modeling efforts.},
  language  = {en}
}
@article{WangShpritsZhelayskayaetal.2019,
  author    = {Wang, Dedong and Shprits, Yuri Y. and Zhelayskaya, Irina S. and Agapitov, Oleksiy and Drozdov, Alexander Y. and Aseev, Nikita A.},
  title     = {Analytical chorus wave model derived from van Allen Probe Observations},
  series = {Journal of geophysical research : Space physics},
  volume    = {124},
  journal   = {Journal of geophysical research : Space physics},
  number    = {2},
  publisher = {American Geophysical Union},
  address   = {Washington},
  issn      = {2169-9380},
  doi       = {10.1029/2018JA026183},
  pages     = {1063 -- 1084},
  year      = {2019},
  abstract  = {Chorus waves play an important role in the dynamic evolution of energetic electrons in the Earth's radiation belts and ring current. Using more than 5 years of Van Allen Probe data, we developed a new analytical model for upper-band chorus (UBC; 0.5fce < f < fce) and lower-band chorus (LBC; 0.05fce < f < 0.5fce) waves, where fce is the equatorial electron gyrofrequency. By applying polynomial fits to chorus wave root mean square amplitudes, we developed regression models for LBC and UBC as a function of geomagnetic activity (Kp), L, magnetic latitude (λ), and magnetic local time (MLT). Dependence on Kp is separated from the dependence on λ, L, and MLT as Kp-scaling law to simplify the calculation of diffusion coefficients and inclusion into particle tracing codes. Frequency models for UBC and LBC are also developed, which depends on MLT and magnetic latitude. This empirical model is valid in all MLTs, magnetic latitude up to 20°, Kp ≤ 6, L-shell range from 3.5 to 6 for LBC and from 4 to 6 for UBC. The dependence of root mean square amplitudes on L are different for different bands, which implies different energy sources for different wave bands. This analytical chorus wave model is convenient for inclusion in quasi-linear diffusion calculations of electron scattering rates and particle simulations in the inner magnetosphere, especially for the newly developed four-dimensional codes, which require significantly improved wave parameterizations.},
  language  = {en}
}
@article{WalkerBoyntonShpritsetal.2022,
  author    = {Walker, Simon N. and Boynton, Richard J. and Shprits, Yuri Y. and Balikhin, Michael A. and Drozdov, Alexander Y.},
  title     = {Forecast of the energetic electron environment of the radiation belts},
  series = {Space Weather: The International Journal of Research and Applications},
  volume    = {20},
  journal   = {Space Weather: The International Journal of Research and Applications},
  number    = {12},
  publisher = {American Geophysical Union},
  address   = {Washington},
  issn      = {1542-7390},
  doi       = {10.1029/2022SW003124},
  pages     = {21},
  year      = {2022},
  abstract  = {Different modeling methodologies possess different strengths and weakness. For instance, data based models may provide superior accuracy but have a limited spatial coverage while physics based models may provide lower accuracy but provide greater spatial coverage. This study investigates the coupling of a data based model of the electron fluxes at geostationary orbit (GEO) with a numerical model of the radiation belt region to improve the resulting forecasts/pastcasts of electron fluxes over the whole radiation belt region. In particular, two coupling methods are investigated. The first assumes an average value for L* for GEO, namely LGEO* L-GEO* = 6.2. The second uses a value of L* that varies with geomagnetic activity, quantified using the Kp index. As the terrestrial magnetic field responds to variations in geomagnetic activity, the value of L* will vary for a specific location. In this coupling method, the value of L* is calculated using the Kp driven Tsyganenko 89c magnetic field model for field line tracing. It is shown that this addition can result in changes in the initialization of the parameters at the Versatile Electron Radiation Belt model outer boundary. Model outputs are compared to Van Allen Probes MagEIS measurements of the electron fluxes in the inner magnetosphere for the March 2015 geomagnetic storm. It is found that the fixed LGEO* L-GEO* coupling method produces a more realistic forecast.},
  language  = {en}
}
@article{ShpritsMeniettiDrozdovetal.2018,
  author    = {Shprits, Yuri Y. and Menietti, J. D. and Drozdov, Alexander Y. and Horne, Richard B. and Woodfield, Emma E. and Groene, J. B. and de Soria-Santacruz, M. and Averkamp, T. F. and Garrett, H. and Paranicas, C. and Gurnett, Don A.},
  title     = {Strong whistler mode waves observed in the vicinity of Jupiter's moons},
  series = {Nature Communications},
  volume    = {9},
  journal   = {Nature Communications},
  publisher = {Nature Publ. Group},
  address   = {London},
  issn      = {2041-1723},
  doi       = {10.1038/s41467-018-05431-x},
  pages     = {6},
  year      = {2018},
  abstract  = {Understanding of wave environments is critical for the understanding of how particles are accelerated and lost in space. This study shows that in the vicinity of Europa and Ganymede, that respectively have induced and internal magnetic fields, chorus wave power is significantly increased. The observed enhancements are persistent and exceed median values of wave activity by up to 6 orders of magnitude for Ganymede. Produced waves may have a pronounced effect on the acceleration and loss of particles in the Jovian magnetosphere and other astrophysical objects. The generated waves are capable of significantly modifying the energetic particle environment, accelerating particles to very high energies, or producing depletions in phase space density. Observations of Jupiter's magnetosphere provide a unique opportunity to observe how objects with an internal magnetic field can interact with particles trapped in magnetic fields of larger scale objects.},
  language  = {en}
}
@article{ShpritsKellermanAseevetal.2017,
  author    = {Shprits, Yuri Y. and Kellerman, Adam C . and Aseev, Nikita A. and Drozdov, Alexander Y. and Michaelis, Ingo},
  title     = {Multi-MeV electron loss in the heart of the radiation belts},
  series = {Geophysical research letters},
  volume    = {44},
  journal   = {Geophysical research letters},
  number    = {3},
  publisher = {American Geophysical Union},
  address   = {Washington},
  issn      = {0094-8276},
  doi       = {10.1002/2016GL072258},
  pages     = {1204 -- 1209},
  year      = {2017},
  abstract  = {Significant progress has been made in recent years in understanding acceleration mechanisms in the Earth's radiation belts. In particular, a number of studies demonstrated the importance of the local acceleration by analyzing the radial profiles of phase space density (PSD) and observing building up peaks in PSD. In this study, we focus on understanding of the local loss using very similar tools. The profiles of PSD for various values of the first adiabatic invariants during the previously studied 17 January 2013 storm are presented and discussed. The profiles of PSD show clear deepening minimums consistent with the scattering by electromagnetic ion cyclotron waves. Long-term evolution shows that local minimums in PSD can persist for relatively long times. During considered interval of time the deepening minimums were observed around L* = 4 during 17 January 2013 storm and around L* = 3.5 during 1 March 2013 storm. This study shows a new method that can help identify the location, magnitude, and time of the local loss and will help quantify local loss in the future. This study also provides additional clear and definitive evidence that local loss plays a major role for the dynamics of the multi-MeV electrons.},
  language  = {en}
}
@article{ShpritsDrozdovSpasojevicetal.2016,
  author    = {Shprits, Yuri Y. and Drozdov, Alexander Y. and Spasojevic, Maria and Kellerman, Adam C. and Usanova, Maria E. and Engebretson, Mark J. and Agapitov, Oleksiy V. and Zhelavskaya, Irina S. and Raita, Tero J. and Spence, Harlan E. and Baker, Daniel N. and Zhu, Hui and Aseev, Nikita A.},
  title     = {Wave-induced loss of ultra-relativistic electrons in the Van Allen radiation belts},
  series = {Nature Communications},
  volume    = {7},
  journal   = {Nature Communications},
  publisher = {Nature Publ. Group},
  address   = {London},
  issn      = {2041-1723},
  doi       = {10.1038/ncomms12883},
  pages     = {7},
  year      = {2016},
  language  = {en}
}
@article{RipollLoridanDentonetal.2019,
  author    = {Ripoll, Jean-Francois and Loridan, Vivien and Denton, Michael H. and Cunningham, Gregory and Reeves, G. and Santolik, O. and Fennell, Joseph and Turner, Drew L. and Drozdov, Alexander Y. and Villa, Juan Sebastian Cervantes and Shprits, Yuri Y. and Thaller, Scott A. and Kurth, William S. and Kletzing, Craig A. and Henderson, Michael G. and Ukhorskiy, Aleksandr Y.},
  title     = {Observations and Fokker-Planck Simulations of the L-Shell, Energy, and Times},
  series = {Journal of geophysical research : Space physics},
  volume    = {124},
  journal   = {Journal of geophysical research : Space physics},
  number    = {2},
  publisher = {American Geophysical Union},
  address   = {Washington},
  issn      = {2169-9380},
  doi       = {10.1029/2018JA026111},
  pages     = {1125 -- 1142},
  year      = {2019},
  abstract  = {The evolution of the radiation belts in L-shell (L), energy (E), and equatorial pitch angle (alpha(0)) is analyzed during the calm 11-day interval (4-15 March) following the 1 March 2013 storm. Magnetic Electron and Ion Spectrometer (MagEIS) observations from Van Allen Probes are interpreted alongside 1D and 3D Fokker-Planck simulations combined with consistent event-driven scattering modeling from whistler mode hiss waves. Three (L, E, alpha(0)) regions persist through 11 days of hiss wave scattering; the pitch angle-dependent inner belt core (L similar to <2.2 and E < 700 keV), pitch angle homogeneous outer belt low-energy core (L > similar to 5 and E similar to < 100 keV), and a distinct pocket of electrons (L similar to [4.5, 5.5] and E similar to [0.7, 2] MeV). The pitch angle homogeneous outer belt is explained by the diffusion coefficients that are roughly constant for alpha(0) similar to <60 degrees, E > 100 keV, 3.5 < L < L-pp similar to 6. Thus, observed unidirectional flux decays can be used to estimate local pitch angle diffusion rates in that region. Top-hat distributions are computed and observed at L similar to 3-3.5 and E = 100-300 keV.},
  language  = {en}
}
@article{KronbergRashevDalyetal.2016,
  author    = {Kronberg, Elena A. and Rashev, M. V. and Daly, P. W. and Shprits, Yuri Y. and Turner, D. L. and Drozdov, Alexander Y. and Dobynde, M. and Kellerman, Adam C. and Fritz, T. A. and Pierrard, V. and Borremans, K. and Klecker, B. and Friedel, R.},
  title     = {Contamination in electron observations of the silicon detector on board},
  series = {Space Weather: The International Journal of Research and Applications},
  volume    = {14},
  journal   = {Space Weather: The International Journal of Research and Applications},
  publisher = {American Geophysical Union},
  address   = {Washington},
  issn      = {1542-7390},
  doi       = {10.1002/2016SW001369},
  pages     = {449 -- 462},
  year      = {2016},
  abstract  = {Since more than 15 years, the Cluster mission passes through Earth's radiation belts at least once every 2 days for several hours, measuring the electron intensity at energies from 30 to 400 keV. These data have previously been considered not usable due to contamination caused by penetrating energetic particles (protons at >100 keV and electrons at >400 keV). In this study, we assess the level of distortion of energetic electron spectra from the Research with Adaptive Particle Imaging Detector (RAPID)/Imaging Electron Spectrometer (IES) detector, determining the efficiency of its shielding. We base our assessment on the analysis of experimental data and a radiation transport code (Geant4). In simulations, we use the incident particle energy distribution of the AE9/AP9 radiation belt models. We identify the Roederer L values, L\&\#8902;, and energy channels that should be used with caution: at 3\&\#8804;L\&\#8902;\&\#8804;4, all energy channels (40-400 keV) are contaminated by protons (\&\#8771;230 to 630 keV and >600 MeV); at L\&\#8902;\&\#8771;1 and 4-6, the energy channels at 95-400 keV are contaminated by high-energy electrons (>400 keV). Comparison of the data with electron and proton observations from RBSP/MagEIS indicates that the subtraction of proton fluxes at energies \&\#8771; 230-630 keV from the IES electron data adequately removes the proton contamination. We demonstrate the usefulness of the corrected data for scientific applications.},
  language  = {en}
}
@article{DrozdovShpritsUsanovaetal.2017,
  author    = {Drozdov, Alexander Y. and Shprits, Yuri Y. and Usanova, Maria E. and Aseev, Nikita A. and Kellerman, Adam C. and Zhu, H.},
  title     = {EMIC wave parameterization in the long-term VERB code simulation},
  series = {Journal of geophysical research : Space physics},
  volume    = {122},
  journal   = {Journal of geophysical research : Space physics},
  publisher = {American Geophysical Union},
  address   = {Washington},
  issn      = {2169-9380},
  doi       = {10.1002/2017JA024389},
  pages     = {8488 -- 8501},
  year      = {2017},
  abstract  = {Electromagnetic ion cyclotron (EMIC) waves play an important role in the dynamics of ultrarelativistic electron population in the radiation belts. However, as EMIC waves are very sporadic, developing a parameterization of such wave properties is a challenging task. Currently, there are no dynamic, activity-dependent models of EMIC waves that can be used in the long-term (several months) simulations, which makes the quantitative modeling of the radiation belt dynamics incomplete. In this study, we investigate Kp, Dst, and AE indices, solar wind speed, and dynamic pressure as possible parameters of EMIC wave presence. The EMIC waves are included in the long-term simulations (1year, including different geomagnetic activity) performed with the Versatile Electron Radiation Belt code, and we compare results of the simulation with the Van Allen Probes observations. The comparison shows that modeling with EMIC waves, parameterized by solar wind dynamic pressure, provides a better agreement with the observations among considered parameterizations. The simulation with EMIC waves improves the dynamics of ultrarelativistic fluxes and reproduces the formation of the local minimum in the phase space density profiles.},
  language  = {en}
}
@article{DrozdovAseevEffenbergeretal.2019,
  author    = {Drozdov, Alexander Y. and Aseev, Nikita A. and Effenberger, Frederic and Turner, Drew L. and Saikin, Anthony and Shprits, Yuri Y.},
  title     = {Storm Time Depletions of Multi-MeV Radiation Belt Electrons Observed at Different Pitch Angles},
  series = {Journal of geophysical research : Space physics},
  volume    = {124},
  journal   = {Journal of geophysical research : Space physics},
  number    = {11},
  publisher = {American Geophysical Union},
  address   = {Washington},
  issn      = {2169-9380},
  doi       = {10.1029/2019JA027332},
  pages     = {8943 -- 8953},
  year      = {2019},
  abstract  = {During geomagnetic storms, the rapid depletion of the high-energy (several MeV) outer radiation belt electrons is the result of loss to the interplanetary medium through the magnetopause, outward radial diffusion, and loss to the atmosphere due to wave-particle interactions. We have performed a statistical study of 110 storms using pitch angle resolved electron flux measurements from the Van Allen Probes mission and found that inside of the radiation belt (L* = 3 - 5) the number of storms that result in depletion of electrons with equatorial pitch angle alpha(eq) = 30 degrees is higher than number of storms that result in depletion of electrons with equatorial pitch angle alpha(eq) = 75 degrees. We conclude that this result is consistent with electron scattering by whistler and electromagnetic ion cyclotron waves. At the outer edge of the radiation belt (L* >= 5.2) the number of storms that result in depletion is also large (similar to 40-50\%), emphasizing the significance of the magnetopause shadowing effect and outward radial transport.},
  language  = {en}
}