Distortion of the ULF wave spatial structure upon transmission through theionosphere

Citation
Va. Pilipenko et al., Distortion of the ULF wave spatial structure upon transmission through theionosphere, J GEO R-S P, 105(A9), 2000, pp. 21225-21236
Citations number
38
Categorie Soggetti
Space Sciences
Journal title
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
ISSN journal
21699380 → ACNP
Volume
105
Issue
A9
Year of publication
2000
Pages
21225 - 21236
Database
ISI
SICI code
0148-0227(20000901)105:A9<21225:DOTUWS>2.0.ZU;2-Y
Abstract
Distortion of the ground-based spatial structure of ULF waves is described in detail using analytical and numerical models of the resonant Alfven wave transmission through the "thin" ionosphere. The numerical calculations hav e been done for geophysical conditions cor responding to the midlatitude Bo rok Observatory and the low-latitude L'Aquila Observatory. As compared with a resonant field-aligned oscillation above the ionosphere, the ground spat ial structure has the following additional features which have not been des cribed by existing models: the amplitude peak is shifted northward, the wid th of it is changed, and amplitude and phase are modified. The effect is mo st evident when the resonant frequency and ionospheric conductivity are hig h. From a physical point of view the effect is caused by two reasons: (1) e xcitation of a diffusive-like surface-type mode in the ionosphere and (2) f inite Earth's conductivity. The possible influence of the predicted distort ion of the ULF field on various ground-based methods for the determination of the magnetospheric resonant frequency is discussed.