| Summary: | Abstract We show the statistical characteristics of quasi-6-day wave (Q6DW) absolute amplitude in foE and foF2 during 2014–2015 by using six ionosondes at different latitudes. The results show that foE perturbations maximized at mid-latitudes during equinoxes, and the maximum amplitude of Q6DW in foF2 occurred near the northern crest of equatorial ionospheric anomaly (EIA). In addition, the absolute amplitude of Q6DW in foF2 increased with increasing solar activity. Our observations suggest that the dissipative Q6DW-like oscillations in the lower thermosphere may cause variations in the thermospheric neutral density via mixing effect and further result in foE disturbances in Q6DW events. Furthermore, the E region wind dynamo could also be modulated by the 6-day wave, thus leading to the disturbances in vertical plasma velocity via E × B drifts and F region electron density. Our observational investigation provides evidence of thermosphere–ionosphere coupling in the mid- and low-latitude region.
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