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CLUSTER observations of lower hybrid waves excited at high altitudes by electromagnetic whistler mode signals from the HAARP facility
Author(s) -
Bell T. F.,
Inan U. S.,
Platino M.,
Pickett J. S.,
Kossey P. A.,
Kennedy E. J.
Publication year - 2004
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 - 10.1029/2003gl018855
Subject(s) - whistler , cluster (spacecraft) , mode (computer interface) , physics , excited state , electromagnetic radiation , environmental science , computational physics , remote sensing , geophysics , geology , optics , atomic physics , nuclear physics , computer science , plasma , operating system , programming language
We report new observations from the CLUSTER spacecraft of strong excitation of lower hybrid (LH) waves by electromagnetic (EM) whistler mode waves at altitudes ≥20,000 km outside the plasmasphere. Previous observations of this phenomenon occurred at altitudes ≤7000 km. The excitation mechanism appears to be linear mode coupling in the presence of small scale plasma density irregularities. These observations provide strong evidence that EM whistler mode waves are continuously transformed into LH waves as the whistler mode waves propagate at high altitudes beyond L ∼ 4. This may explain the lack of lightning generated whistlers observed in this same region of space.