scholarly journals Modeling radiation belt radial diffusion in ULF wave fields: 1. Quantifying ULF wave power at geosynchronous orbit in observations and in global MHD model

2010 ◽  
Vol 115 (A6) ◽  
pp. n/a-n/a ◽  
Author(s):  
Chia-Lin Huang ◽  
Harlan E. Spence ◽  
Howard J. Singer ◽  
W. Jeffrey Hughes
Keyword(s):  
Radiation Belt ◽  
Radial Diffusion ◽  
Geosynchronous Orbit ◽  
Wave Power ◽  
Wave Fields ◽  
Ulf Wave ◽  
Mhd Model

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 Modeling radiation belt radial diffusion in ULF wave fields: 2. Estimating rates of radial diffusion using combined MHD and particle codes

2010 ◽  
Vol 115 (A6) ◽  
pp. n/a-n/a ◽  
Author(s):  
Chia-Lin Huang ◽  
Harlan E. Spence ◽  
Mary K. Hudson ◽  
Scot R. Elkington
Keyword(s):  
Radiation Belt ◽  
Radial Diffusion ◽  
Wave Fields ◽  
Ulf Wave

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

ULF Wave-Driven Radial Diffusion Simulations of the Outer Radiation Belt

2013 ◽  
pp. 139-150 ◽  
Author(s):  
Louis G. Ozeke ◽  
Ian R. Mann ◽  
Kyle R. Murphy ◽  
I. Jonathan Rae ◽  
Anthony A. Chan
Keyword(s):  
Radiation Belt ◽  
Radial Diffusion ◽  
Outer Radiation Belt ◽  
Ulf Wave

The magnetospheric interactions of predicted ULF wave power

2021 ◽  
Author(s):  
Sarah Bentley ◽  
Rhys Thompson ◽  
Clare Watt ◽  
Jennifer Stout ◽  
Teo Bloch
Keyword(s):  
Solar Wind ◽  
Radiation Belt ◽  
Internal State ◽  
Low Frequency ◽  
Ulf Waves ◽  
Wave Power ◽  
Ulf Wave ◽  
Radiation Belt Electrons ◽  
Spatial Parameters ◽  
The Given

<p>We present and analyse a freely-available model of the power found in ultra-low frequency waves (ULF, 1-15 mHz) throughout Earth’s magnetosphere. Predictions can be used to test our understanding of magnetospheric dynamics, while accurate models of these waves are required to characterise the energisation and transport of radiation belt electrons in space weather.</p><p>This model is constructed using decision tree ensembles, which iteratively partition the given parameter space into variable size bins. Wave power is determined by physical driving parameters (e.g. solar wind properties) and spatial parameters of interest (magnetic local time MLT, magnetic latitude and frequency). As a parameterised model, there is no guarantee that individual physical processes can be extracted and analysed. However, by iteratively considering smaller scale driving processes, we identify predominant wave drivers and find that solar wind driving of ULF waves are moderated by internal magnetospheric conditions. Significant remaining uncertainty occurs with mild solar wind driving, suggesting that the internal state of the magnetosphere should be included in future.</p><p>Models such as this may be used to create global magnetospheric “maps” of predicted wave power which may then be used to create radial diffusion coefficients determining the effect of ULF waves on radiation belt electrons.</p>

Ultra-relativistic radiation belt extinction and ULF wave radial diffusion: Modeling the September 2014 extended dropout event

2017 ◽  
Vol 44 (6) ◽  
pp. 2624-2633 ◽  
Author(s):  
Louis G. Ozeke ◽  
Ian R. Mann ◽  
Kyle R. Murphy ◽  
David G. Sibeck ◽  
Daniel N. Baker
Keyword(s):  
Radiation Belt ◽  
Radial Diffusion ◽  
Diffusion Modeling ◽  
Ulf Wave

scholarly journals Effects of ULF wave power on relativistic radiation belt electrons: 8-9 October 2012 geomagnetic storm

2016 ◽  
Vol 121 (12) ◽  
pp. 11,766-11,779 ◽  
Author(s):  
D. Pokhotelov ◽  
I. J. Rae ◽  
K. R. Murphy ◽  
I. R. Mann ◽  
L. Ozeke
Keyword(s):  
Geomagnetic Storm ◽  
Radiation Belt ◽  
Wave Power ◽  
Ulf Wave ◽  
Radiation Belt Electrons

scholarly journals Analytic expressions for ULF wave radiation belt radial diffusion coefficients

2014 ◽  
Vol 119 (3) ◽  
pp. 1587-1605 ◽  
Author(s):  
Louis G. Ozeke ◽  
Ian R. Mann ◽  
Kyle R. Murphy ◽  
I. Jonathan Rae ◽  
David K. Milling
Keyword(s):  
Diffusion Coefficients ◽  
Radiation Belt ◽  
Radial Diffusion ◽  
Wave Radiation ◽  
Ulf Wave ◽  
Analytic Expressions

scholarly journals ULF wave analysis and radial diffusion calculation using a global MHD model for the 17 March 2013 and 2015 storms

2017 ◽  
Vol 122 (7) ◽  
pp. 7353-7363 ◽  
Author(s):  
Zhao Li ◽  
Mary Hudson ◽  
Maulik Patel ◽  
Michael Wiltberger ◽  
Alex Boyd ◽  
...  
Keyword(s):  
Radial Diffusion ◽  
Wave Analysis ◽  
Ulf Wave ◽  
Diffusion Calculation ◽  
Mhd Model
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