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Thermospheric observations of equatorial wavenumber 4 density perturbations from WINDII data
Author(s) -
Shepherd Gordon G.
Publication year - 2011
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 - 10.1029/2011gl046986
Subject(s) - wavenumber , thermosphere , geology , atmospheric sciences , geophysics , physics , perturbation (astronomy) , geodesy , environmental science , ionosphere , astronomy , optics
Previous studies have established that the diurnal eastward‐propagating non‐migrating tide of wavenumber 3 (DE3) is produced by latent heat release in deep tropospheric convection and therefore is longitude dependent. Longitudinal variations of F‐region ionospheric electron density show a zonal wavenumber 4 pattern, expected for satellite observations of DE3 for a fixed local time with respect to a rotating Earth. Satellite observations of winds show wavenumber 4 reaching 180 km, indicating neutral coupling of the troposphere with the thermosphere. In the present work, WINDII measurements of O( 1 S) green line emission at 250 km excited by photoelectron impact on atomic oxygen are interpreted as neutral density observations; showing wavenumber 4 to be a common density perturbation, with a fractional amplitude variation of about 10%. This result confirms direct neutral coupling of troposphere and thermosphere but also opens the way to other studies of neutral density variations at 250 km.