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Pervasive small‐scale enhancements in mantle and polar rain precipitation
Author(s) -
Veselovsky Igor S.,
Newell Patrick T.,
Lui Anthony T. Y.
Publication year - 1995
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/95gl03087
Subject(s) - magnetosphere , polar , geophysics , electron precipitation , magnetosheath , geology , latitude , precipitation , ionosphere , physics , spectral line , atmospheric sciences , magnetic field , geodesy , magnetopause , astronomy , meteorology , quantum mechanics
Short duration bursts—1–3 s or 0.05–0.15° MLAT—of 32 eV to several hundred eV electrons are regularly observed in the polar rain and mantle precipitation regions by the DMSP satellites. The spacing between bursts is typically 9–12 s (70–90 km) and is sometimes regular but more often irregular. Sometimes quasi‐periodic trains of 4 or 5 evenly spaced bursts occur. Electron spectra in the bursts are variable, but typically represent an enhancement of an order of magnitude in the spectral differential energy flux, but without showing signs of field‐aligned acceleration. Previous reports of bursty polar cap precipitation consisted of precipitation with large scale (hundreds of km) spatial inhomogeneity of plasma sheet origin under northward IMF conditions. The bursts described herein occur for southward as well as northward IMF B z , and represent fine structure (7.5 km) within regions that are of magnetosheath origin and which are homogenous over larger spatial scales (>∼100 km). We suggest that the observed phenomena may be related to the nonstationary processes in the outer high latitude magnetosphere.