A New Four-Component L*-Dependent Model for Radial Diffusion Based on Solar Wind and Magnetospheric Drivers of ULF Waves

被引：3

作者：

Murphy, Kyle R. R. ^{[1
,2
]}

Sandhu, Jasmine ^{[1
]}

Rae, I. Jonathan ^{[1
]}

Daggitt, Thomas ^{[3
,4
]}

Glauert, Sarah ^{[3
]}

Horne, Richard B. B. ^{[3
]}

Watt, Clare E. J. ^{[1
]}

Bentley, Sarah ^{[1
]}

Kellerman, Adam ^{[5
]}

Ozeke, Louis ^{[6
]}

Halford, Alexa J. J. ^{[7
]}

Tian, Sheng ^{[8
,9
]}

Breneman, Aaron ^{[7
]}

Olifer, Leonid ^{[6
]}

Mann, Ian R. R. ^{[1
,6
]}

Angelopoulos, Vassilis ^{[5
]}

Wygant, John ^{[9
]}

机构：

[1] Northumbria Univ, Dept Maths Phys & Elect Engn, Newcastle Upon Tyne, England

[2] Lakehead Univ, Dept Phys, Thunder Bay, ON, Canada

[3] British Antarctic Survey, Cambridge, England

[4] Univ Cambridge, Dept Appl Math & Theoret Phys, Cambridge, England

[5] Univ Calif Los Angeles, Dept Earth Planetary & Space Sci, Los Angeles, CA USA

[6] Univ Alberta, Dept Phys, Edmonton, AB, Canada

[7] NASA, Goddard Spaceflight Ctr, Greenbelt, MD USA

[8] Univ Calif Los Angeles, Dept Atmospher & Ocean Sci, Los Angeles, CA USA

[9] Univ Minnesota, Sch Phys & Astron, Minneapolis, MN USA

来源：

SPACE WEATHER-THE INTERNATIONAL JOURNAL OF RESEARCH AND APPLICATIONS | 2023年 / 21卷 / 07期

基金：

加拿大自然科学与工程研究理事会;

关键词：

LOW FREQUENCY WAVES; BELT ELECTRONS; ACCELERATION; SCATTERING; LOSSES;

D O I：

10.1029/2023SW003440

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

Waves which couple to energetic electrons are particularly important in space weather, as they drive rapid changes in the topology and intensity of Earth's outer radiation belt during geomagnetic storms. This includes Ultra Low Frequency (ULF) waves that interact with electrons via radial diffusion which can lead to electron dropouts via outward transport and rapid electron acceleration via inward transport. In radiation belt simulations, the strength of this interaction is specified by ULF wave radial diffusion coefficients. In this paper we detail the development of new models of electric and magnetic radial diffusion coefficients derived from in-situ observations of the azimuthal electric field and compressional magnetic field. The new models use L* as it accounts for adiabatic changes due to the dynamic magnetic field coupled with an optimized set of four components of solar wind and geomagnetic activity, B-z, V, P-dyn, and Sym - H, as independent variables (inputs). These independent variables are known drivers of ULF waves and offer the ability to calculate diffusion coefficients at a higher cadence then existing models based on Kp. We investigate the performance of the new models by characterizing the model residuals as a function of each independent variable and by comparing to existing radial diffusion models during a quiet geomagnetic period and through a geomagnetic storm. We find that the models developed here perform well under varying levels of activity and have a larger slope or steeper gradient as a function of L* as compared to existing models (higher diffusion at higher L* values). Plain Language Summary The outer radiation belt is a region of space comprising highly energetic electrons. During periods of extreme space weather, the number and energy of these electrons can rapidly vary. During these periods as the electron energies and numbers become enhanced, they can pose a threat to satellite and space infrastructure. While we have an excellent understanding of the physical processes which drive radiation belt electron dynamics, we still have a limited ability to model and forecast radiation belt dynamics; this is a result of the complexity of Earth's radiation belt system. One of the key processes controlling radiation belt dynamics is Ultra Low Frequency (ULF) wave radial diffusion. In this work we detail the development a new model quantifying the strength of ULF wave radial diffusion in the outer radiation belt utilizing space base observations of the electric and magnetic fields in Earth's magnetosphere. Accurately quantifying ULF wave radial diffusion is fundamental to understanding radiation belt dynamics and any improvement or refinements in radial diffusion models can help to provide a better understanding of the complex radiation belt system and importantly improve hindcasts, nowcasts, and forecasts.

引用

页数：20