scholarly journals On the Close Correspondence Between Storm Time ULF Wave Power and the POES VLF Chorus Wave Amplitude Proxy

2019 ◽  
Vol 46 (4) ◽  
pp. 1947-1955
Author(s):  
Stavros Dimitrakoudis ◽  
Ian R. Mann
Keyword(s):  
Wave Amplitude ◽  
Wave Power ◽  
Close Correspondence ◽  
Ulf Wave ◽  
Chorus Wave

ULF Wave Power During Geomagnetic Storms and Implications for Radial Diffusion Processes

2021 ◽  
Author(s):  
Jasmine Sandhu ◽  
Jonathan Rae ◽  
John Wygant ◽  
Aaron Breneman ◽  
Sheng Tian ◽  
...  
Keyword(s):  
Statistical Analysis ◽  
Diffusion Coefficients ◽  
Radiation Belt ◽  
Geomagnetic Storms ◽  
Radial Diffusion ◽  
Ulf Waves ◽  
Wave Power ◽  
Outer Radiation Belt ◽  
Large Variability ◽  
Ulf Wave

<p>Ultra Low Frequency (ULF) waves drive radial diffusion of radiation belt electrons, where this process contributes to and, at times, dominates energisation, loss, and large scale transport of the outer radiation belt. In this study we quantify the changes and variability in ULF wave power during geomagnetic storms, through a statistical analysis of Van Allen Probes data for the time period spanning 2012 – 2019. The results show that global wave power enhancements occur during the main phase, and continue into the recovery phase of storms. Local time asymmetries show sources of ULF wave power are both external solar wind driving as well as internal sources from coupling with ring current ions and substorms.</p><p>The statistical analysis demonstrates that storm time ULF waves are able to access lower L values compared to pre-storm conditions, with enhancements observed within L = 4. We assess how magnetospheric compressions and cold plasma distributions shape how ULF wave power propagates through the magnetosphere. Results show that the Earthward displacement of the magnetopause is a key factor in the low L enhancements. Furthermore, the presence of plasmaspheric plumes during geomagnetic storms plays a crucial role in trapping ULF wave power, and contributes significantly to large storm time enhancements in ULF wave power.</p><p>The results have clear implications for enhanced radial diffusion of the outer radiation belt during geomagnetic storms. Estimates of storm time radial diffusion coefficients are derived from the ULF wave power observations, and compared to existing empirical models of radial diffusion coefficients. We show that current Kp-parameterised models, such as the Ozeke et al. [2014] model, do not fully capture the large variability in storm time radial diffusion coefficients or the extent of enhancements in the magnetic field diffusion coefficients.</p>

scholarly journals Field-aligned chorus wave spectral power in Earth's outer radiation belt

2015 ◽  
Vol 33 (5) ◽  
pp. 583-597 ◽  
Author(s):  
H. Breuillard ◽  
O. Agapitov ◽  
A. Artemyev ◽  
E. A. Kronberg ◽  
S. E. Haaland ◽  
...  
Keyword(s):  
Pitch Angle ◽  
Radiation Belt ◽  
Spectral Power ◽  
Peak Frequency ◽  
Wave Power ◽  
Outer Radiation Belt ◽  
Substantial Impact ◽  
Wide Range ◽  
Frequency Variations ◽  
Chorus Wave

Abstract. Chorus-type whistler waves are one of the most intense electromagnetic waves generated naturally in the magnetosphere. These waves have a substantial impact on the radiation belt dynamics as they are thought to contribute to electron acceleration and losses into the ionosphere through resonant wave–particle interaction. Our study is devoted to the determination of chorus wave power distribution on frequency in a wide range of magnetic latitudes, from 0 to 40°. We use 10 years of magnetic and electric field wave power measured by STAFF-SA onboard Cluster spacecraft to model the initial (equatorial) chorus wave spectral power, as well as PEACE and RAPID measurements to model the properties of energetic electrons (~ 0.1–100 keV) in the outer radiation belt. The dependence of this distribution upon latitude obtained from Cluster STAFF-SA is then consistently reproduced along a certain L-shell range (4 ≤ L ≤ 6.5), employing WHAMP-based ray tracing simulations in hot plasma within a realistic inner magnetospheric model. We show here that, as latitude increases, the chorus peak frequency is globally shifted towards lower frequencies. Making use of our simulations, the peak frequency variations can be explained mostly in terms of wave damping and amplification, but also cross-L propagation. These results are in good agreement with previous studies of chorus wave spectral extent using data from different spacecraft (Cluster, POLAR and THEMIS). The chorus peak frequency variations are then employed to calculate the pitch angle and energy diffusion rates, resulting in more effective pitch angle electron scattering (electron lifetime is halved) but less effective acceleration. These peak frequency parameters can thus be used to improve the accuracy of diffusion coefficient calculations.

scholarly journals A prediction model for the global distribution of whistler chorus wave amplitude developed separately for two latitudinal zones

2015 ◽  
Vol 120 (4) ◽  
pp. 2819-2837 ◽  
Author(s):  
Jin-Hee Kim ◽  
Dae-Young Lee ◽  
Jung-Hee Cho ◽  
Dae-Kyu Shin ◽  
Kyung-Chan Kim ◽  
...  
Keyword(s):  
Prediction Model ◽  
Wave Amplitude ◽  
Global Distribution ◽  
Chorus Wave

On the interplay between solar wind parameters and ULF wave power as a function of geomagnetic activity at high‐ and mid‐latitudes

2021 ◽  
Author(s):  
Stavros Dimitrakoudis ◽  
Ian R. Mann ◽  
Georgios Balasis ◽  
Constantinos Papadimitriou ◽  
Anastasios Anastasiadis ◽  
...  
Keyword(s):  
Solar Wind ◽  
Geomagnetic Activity ◽  
Wave Power ◽  
Ulf Wave ◽  
Solar Wind Parameters

scholarly journals On the dependence of storm time ULF wave power on magnetopause location: Impacts for ULF wave radial diffusion

2015 ◽  
Vol 42 (22) ◽  
pp. 9676-9684 ◽  
Author(s):  
Kyle R. Murphy ◽  
Ian R. Mann ◽  
David G. Sibeck
Keyword(s):  
Radial Diffusion ◽  
Wave Power ◽  
Ulf Wave

scholarly journals Correspondence between the latitudinal ULF wave power distribution and auroral oval in conjugate ionospheres

2018 ◽  
Author(s):  
V.A. Martines-Bedenko ◽  
V.A. Pilipenko ◽  
M.D. Hartinger ◽  
M.J. Engebretson ◽  
D.A. Lorentzen ◽  
...  
Keyword(s):  
Power Distribution ◽  
Auroral Oval ◽  
Wave Power ◽  
Ulf Wave

scholarly journals The Roles of the Magnetopause and Plasmapause in Storm‐Time ULF Wave Power Enhancements

2021 ◽  
Author(s):  
J. K. Sandhu ◽  
I. J. Rae ◽  
F. A. Staples ◽  
D. P. Hartley ◽  
M.‐T. Walach ◽  
...  
Keyword(s):  
Wave Power ◽  
Ulf Wave

The Angular Distribution of Whistler-Mode Chorus and the Importance of Plumes in the Chorus-Hiss Mechanism

2020 ◽  
Author(s):  
David P. Hartley ◽  
Lunjin Chen ◽  
Craig Kletzing ◽  
Richard Horne ◽  
Ondrej Santolik
Keyword(s):  
Ray Tracing ◽  
Wave Vector ◽  
Initial Conditions ◽  
Large Fraction ◽  
Wave Power ◽  
Statistical Distributions ◽  
Chorus Waves ◽  
Van Allen Probes ◽  
Vector Orientation ◽  
Chorus Wave

<p>Correlations between chorus waves and plasmaspheric hiss have been directly observed, leading to the proposition that the two wave modes are causally linked. Ray tracing simulations have confirmed that chorus waves can propagate into the plasmasphere and be a source of plasmaspheric hiss, but only for a specific set of initial conditions, particularly relating to the orientation of the wave vector at the chorus source. In this study, both survey and burst mode observations from the Van Allen Probes EMFISIS Waves instrument are coupled with ray tracing simulations to determine the fraction of chorus wave power that exists with the conditions required to enter the plasmasphere. In general, it is found that only a small fraction (< 2%) of chorus wave power exists with the required wave vector orientation. An exception is found when the chorus source is located close to a plasmaspheric plume. Here, azimuthal density gradients modify the wave propagation to permit a large fraction, up to 94%, of chorus wave power to access the plasmasphere. Therefore plasmaspheric plumes are identified as an important access region if a significant fraction of chorus wave power is to enter the plasmasphere and be a source of plasmaspheric hiss. To provide context, we note that plumes are most commonly observed on the dusk side whereas chorus wave power typically peak on the dawn side. The post-noon sector, where these two statistical distributions overlap, appears to be key for observing correlations between chorus and hiss. As such, particular attention is devoted to this region.</p>

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