ULF Geomagnetic Power near <i>L</i> = 4, 2. Temporal Variation of the Radial Diffusion Coefficient for Relativistic Electrons

TitleULF Geomagnetic Power near L = 4, 2. Temporal Variation of the Radial Diffusion Coefficient for Relativistic Electrons
Publication TypeJournal Article
Year of Publication1973
AuthorsLanzerotti, LJ, Morgan, CG
JournalJournal of Geophysical Research
Volume78
Pagination4600 - 4610
Date Published08/1973
ISSN0148-0227
KeywordsRadial Transport
AbstractMeasurements at conjugate points on the ground near L = 4 of the power spectra of magnetic-field fluctuations in the frequency range 0.5 to 20 mHz are used as a means of estimating daily values for the relativistic-electron radial-diffusion coefficient DLL for two periods in December 1971 and January 1972. The values deduced for L−10 DLL show a strong variation with magnetic activity, as measured by the Fredricksburg magnetic index KFR. The radial-diffusion coefficient typically increases by a factor of ∼10 for a unit increase in KFR. When KFR ≲ 2, it is generally found that DLL ≲ 2 × 10−9 L10 day−1 for equatorially mirroring electrons having a first invariant M = 750 Mev/gauss; a value of DLL ∼4 × 10−7 L10 day−1 is deduced for one day on which the mean KFR was 4.5. The quantity L−10 DLL theoretically depends on energy and L as (L/M)(s−2)/2 for relativistic particles, where s is the logarithmic slope of the power-law spectrum of magnetic fluctuations observed on the ground. For the time period analyzed, s typically had values between 1 and 3.
URLhttp://onlinelibrary.wiley.com/doi/10.1029/JA078i022p04600/abstract
DOI10.1029/JA078i022p04600


Page Last Modified: July 28, 2014