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Nonmigrating tidal modulation of the equatorial thermosphere and ionosphere anomaly
Author(s) -
Lei Jiuhou,
Thayer Jeffrey P.,
Wang Wenbin,
Yue Jia,
Dou Xiankang
Publication year - 2014
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1002/2013ja019749
Subject(s) - thermosphere , ionosphere , atmospheric tide , dynamo , atmospheric sciences , geophysics , geology , mesosphere , anomaly (physics) , atmosphere (unit) , physics , meteorology , magnetic field , quantum mechanics , condensed matter physics , stratosphere
The modulation of nonmigrating tides on both the ionospheric equatorial ionization anomaly (EIA) and the equatorial thermosphere anomaly (ETA) is investigated on the basis of simulations from the Thermosphere Ionosphere Mesosphere Electrodynamics General Circulation Model (TIME‐GCM). Our simulations demonstrate the distinct features of the EIA and ETA seen in observations after the inclusion of field‐aligned ion drag in the model. Both the EIA and the ETA in the constant local time frame display an obvious zonal wave‐4 structure associated with the modulation of nonmigrating tides. However, the modeled EIA and ETA show a primary zonal wave‐1 structure when only the migrating tides are specified at the model lower boundary. Our simulations reveal that the zonal wave‐4 structure of the ETA under both low and high solar activity conditions is mainly caused by the direct response of the upper thermosphere to the diurnal eastward wave number 3 and semidiurnal eastward wave number 2 nonmigrating tides from the lower atmosphere. There is a minor contribution from the ion‐neutral coupling. The zonal wave‐4 structure of the EIA is also caused by these nonmigrating tides but through the modulation of the neutral wind dynamo.