Geomagnetic field fluctuations at synchronous orbit 2. Radial diffusion

Lanzerotti, L. J.; Webb, David C.; Arthur, C. W.

doi:10.1029/ja083ia08p03866

Cited by 63 publications

(55 citation statements)

References 28 publications

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“…The value of D LL can be increased by several orders of magnitude during strong magnetic activity (e.g., Tverskoy, 1969;Lanzerotti et al, 1978;Walt, 1994). It also depends on the phase of the solar cycle, the state of the ionosphere, and the spectral density of electromagnetic fluctuations (pulsations) in the range of ultralow frequency (ULF).…”

Section: Introductionmentioning

confidence: 99%

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Deduction of the rates of radial diffusion of protons from the structure of the Earth's radiation belts

Kovtyukh

2016

Ann. Geophys.

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Abstract. From the data on the fluxes and energy spectra of protons with an equatorial pitch angle of α 0 ≈ 90 • during quiet and slightly disturbed (Kp ≤ 2) periods, I directly calculated the value D LL , which is a measure of the rate of radial transport (diffusion) of trapped particles. This is done by successively solving the systems (chains) of integrodifferential equations which describe the balance of radial transport/acceleration and ionization losses of low-energy protons of the stationary belt. This was done for the first time. For these calculations, I used data of International SunEarth Explorer 1 (ISEE-1) for protons with an energy of 24 to 2081 keV at L = 2-10 and data of Explorer-45 for protons with an energy of 78.6 to 872 keV at L = 2-5. Ionization losses of protons (Coulomb losses and charge exchange) were calculated on the basis of modern models of the plasmasphere and the exosphere. It is shown that for protons with µ from ∼ 0.7 to ∼ 7 keV nT −1 at L≈ 4.5-10, the functions of D LL can be approximated by the following equivalent expressions:, where f d is the drift frequency of the protons (in mHz), D LL is measured in s −1 , E is measured in kiloelectronvolt and µ is measured in kiloelectronvolt per nanotesla. These results are consistent with the radial diffusion of particles under the action of the electric field fluctuations (pulsations) in the range of Pc6 and contradict the mechanism of the radial diffusion of particles under the action of sudden impulses (SIs) of the magnetic field and also under the action of substorm impulses of the electric field. During magnetic storms D LL increases, and the expressions for D LL obtained here can change completely.

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Section: Introductionmentioning

confidence: 99%

“…The spectra of the fluctuations of magnetic and electric fields in the range of ULF were also obtained from satellites (e.g., Lanzerotti et al, 1978;Holzworth and Mozer, 1979;Lanzerotti and Wolfe, 1980;Ali et al, 2015). The results of these estimates of D LL differ from each other by several orders of magnitude.…”

Section: Introductionmentioning

confidence: 99%

Deduction of the rates of radial diffusion of protons from the structure of the Earth's radiation belts

Kovtyukh

2016

Ann. Geophys.

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“…To circumvent the prob lem of incomplete data coverage by CRRES during the storm, the CRRES prestorm boundary fluxes were used, scaled by stormtime LANL/SOPA geosynchronous data. The electric and magnetic radial diffusion coefficients were modeled in a Kp-dependent way, by fitting to pre viously reported values over the range Kp = 1-6 [Lyons and Thome, 1973;Lyons and Schulz, 1989;Lanzerotti and Morgan, 1973;Lanzerotti et al, 1978]. This re…”

Section: Outer Zone Electrons During the Moderate Storm Of October 9mentioning

confidence: 99%

Dynamic Radiation Belt Modeling at the Air Force Research Laboratory

Albert

Brautigam

Hilmer

et al. 2013

Geophysical Monograph Series

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Despite its well-known limitations, diffusion remains an important con cept for modeling radiation belt energization and transport. Recent work at AFRL has applied radial diffusion to observations of: (a) 1 -10 MeV equatorially mirroring protons at 1.2 < L < 3, before and after the March 1991 magnetic storm; (b) ~ 1 MeV electrons at 3.5 < L < 6 following the 9 October 1990 storm; (c) 1.6 -3.2 MeV electrons at L = 4.2 between Decem ber 1994 and September 1996, following enhancements of > 2 MeV electrons at geosynchronous orbit associated with high speed solar wind streams. In general, encouraging results were obtained, but only after implementing: (1) non-steady state initial conditions; (2) time-dependent boundary condi tions; (3) realistic magnetic field models; (4) tweaked, scaled, fit, activitydependent, or enhanced diffusion coefficients. This paper reviews these var ious modeling efforts, including the modifications that they required, their successes and failures, and lessons learned.

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Section: Outer Zone Electrons During the Moderate Storm Of October 9mentioning

confidence: 99%

Space Weather

2001

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Geomagnetic field fluctuations at synchronous orbit 2. Radial diffusion

Cited by 63 publications

References 28 publications

Deduction of the rates of radial diffusion of protons from the structure of the Earth's radiation belts

Deduction of the rates of radial diffusion of protons from the structure of the Earth's radiation belts

Dynamic Radiation Belt Modeling at the Air Force Research Laboratory

Space Weather

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