Found 6 results
Filters: Author is Usanova, M. E.  [Clear All Filters]
Authors: Drozdov A. Y., Shprits Y Y, Usanova M. E., Aseev N. A., Kellerman A. C., et al.
Title: EMIC wave parameterization in the long-term VERB code simulation
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 (1 year, including different geomagnetic activity) performed with the Versatile Electron Radiation Belt code, and we co. . .
Date: 08/2017 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2017JA024389 Available at:
More Details
Authors: Aseev N. A., Shprits Y Y, Drozdov A. Y., Kellerman A. C., Usanova M. E., et al.
Title: Signatures of Ultrarelativistic Electron Loss in the Heart of the Outer Radiation Belt Measured by Van Allen Probes
Abstract: Up until recently, signatures of the ultrarelativistic electron loss driven by electromagnetic ion cyclotron (EMIC) waves in the Earth's outer radiation belt have been limited to direct or indirect measurements of electron precipitation or the narrowing of normalized pitch angle distributions in the heart of the belt. In this study, we demonstrate additional observational evidence of ultrarelativistic electron loss that can be driven by resonant interaction with EMIC waves. We analyzed the profiles derived from Van Allen Probe particle data as a function of time and three adiabatic invariants between 9 October and 29 November 2012. New local minimums in the profiles are accompanied by the narrowing of normalized pitch angle distributions and ground-based detection of EMIC waves. Such a cor. . .
Date: 09/2017 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2017JA024485 Available at:
More Details
Authors: Usanova M. E., Malaspina D. M., Jaynes A. N., Bruder R. J., Mann I. R., et al.
Title: Van Allen Probes observations of oxygen cyclotron harmonic waves in the inner magnetosphere
Abstract: Waves with frequencies in the vicinity of the oxygen cyclotron frequency and its harmonics have been regularly observed on the Van Allen Probes satellites during geomagnetic storms. We focus on properties of these waves and present events from the main phase of two storms on 1 November 2012 and 17 March 2013 and associated dropouts of a few MeV electron fluxes. They are electromagnetic, in the frequency range ~0.5 to several Hz, and amplitude ~0.1 to a few nT in magnetic and ~0.1 to a few mV/m in electric field, with both the wave velocity and the Poynting vector directed almost parallel to the background magnetic field. These properties are very similar to those of electromagnetic ion cyclotron waves, which are believed to contribute to loss of ring current ions and radiation belt electro. . .
Date: 09/2016 Publisher: Geophysical Research Letters Pages: 8827 - 8834 DOI: 10.1002/grl.v43.1710.1002/2016GL070233 Available at:
More Details
Authors: Hwang J., Choi E.-J., Park J.-S., Fok M.-C., Lee D.-Y., et al.
Title: Comprehensive analysis of the flux dropout during 7-8 November 2008 storm using multi-satellites observations and RBE model
Abstract: We investigate an electron flux dropout during a weak storm on 7–8 November 2008, with Dst minimum value being −37 nT. During this period, two clear dropouts were observed on GOES 11 > 2 MeV electrons. We also find a simultaneous dropout in the subrelativistic electrons recorded by Time History of Events and Macroscale Interactions during Substorms probes in the outer radiation belt. Using the Radiation Belt Environment model, we try to reproduce the observed dropout features in both relativistic and subrelativistic electrons. We found that there are local time dependences in the dropout for both observation and simulation in subrelativistic electrons: (1) particle loss begins from nightside and propagates into dayside and (2) resupply starts from near dawn magnetic local time . . .
Date: 05/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2015JA021085 Available at:
More Details
Authors: Usanova M. E., Drozdov A., Orlova K., Mann I. R., Shprits Y., et al.
Title: Effect of EMIC waves on relativistic and ultrarelativistic electron populations: Ground-based and Van Allen Probes observations
Abstract: We study the effect of electromagnetic ion cyclotron (EMIC) waves on the loss and pitch angle scattering of relativistic and ultrarelativistic electrons during the recovery phase of a moderate geomagnetic storm on 11 October 2012. The EMIC wave activity was observed in situ on the Van Allen Probes and conjugately on the ground across the Canadian Array for Real-time Investigations of Magnetic Activity throughout an extended 18 h interval. However, neither enhanced precipitation of >0.7 MeV electrons nor reductions in Van Allen Probe 90° pitch angle ultrarelativistic electron flux were observed. Computed radiation belt electron pitch angle diffusion rates demonstrate that rapid pitch angle diffusion is confined to low pitch angles and cannot reach 90°. For the first time, from both obse. . .
Date: 03/2014 Publisher: Geophysical Research Letters Pages: 1375 - 1381 DOI: 10.1002/2013GL059024 Available at:
More Details
Authors: Mann I. R., Usanova M. E., Murphy K., Robertson M. T., Milling D. K., et al.
Title: Spatial localization and ducting of EMIC waves: Van Allen Probes and ground-based observations
Abstract: On 11 October 2012, during the recovery phase of a moderate geomagnetic storm, an extended interval (> 18 h) of continuous electromagnetic ion cyclotron (EMIC) waves was observed by Canadian Array for Real-time Investigations of Magnetic Activity and Solar-Terrestrial Environment Program induction coil magnetometers in North America. At around 14:15 UT, both Van Allen Probes B and A (65° magnetic longitude apart) in conjunction with the ground array observed very narrow (ΔL ~ 0.1–0.4) left-hand polarized EMIC emission confined to regions of mass density gradients at the outer edge of the plasmasphere at L ~ 4. EMIC waves were seen with complex polarization patterns on the ground, in good agreement with model results from Woodroffe and Lysak (2012) and consistent with Earth's . . .
Date: 02/2014 Publisher: Geophysical Research Letters Pages: 785 - 792 DOI: 10.1002/2013GL058581 Available at:
More Details