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A comparison of ionospheric O + /light‐ion transition height derived from ion‐composition measurements and the topside ion density profiles over equatorial latitudes
Author(s) -
Tulasi Ram S.,
Liu C. H.,
Su S.Y.,
Heelis R. A.
Publication year - 2010
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 - 10.1029/2010gl045199
Subject(s) - ionosphere , ion , f region , equator , ionization , scale height , latitude , anomaly (physics) , atmospheric sciences , physics , atomic physics , geophysics , astrophysics , astronomy , condensed matter physics , quantum mechanics
A comparative investigation is made, for the first time, of direct (ion‐composition measurements) and indirect (from topside ion density profiles) methods to determine the O + /light‐ion transition height over equatorial latitudes. The transition height determined from the ion‐composition follows similar latitudinal and local time variations as the underlying Equatorial Ionization Anomaly (EIA) in the F‐region ionosphere. The north‐south hemispheric asymmetries in the transition height from ion composition are consistent with the summer‐to‐winter interhemispheric neutral wind patterns. On the other hand, the transition height derived from ion density profiles is chiefly influenced by changes in the scale height (shape) due to vertical E × B drift at the equator and steep vertical ion density gradients in topside ionosphere. As a result, the transition height derived from topside profiles are systematically lower and exhibit inconsistent latitudinal and local time variations when compared to direct ion‐composition measurements at equatorial latitudes.