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Abstract The Madden–Julian Oscillation (MJO), a recurring intraseasonal (30–96 days) disturbance in the troposphere, strongly influences the E‐region and F‐region ionosphere through its modulation of atmospheric tides. Among these, the diurnal eastward wave number 3 (DE3) tide, driven by MJO‐modulated latent heating, carries MJO signals upward into the E‐region. However, coupling into the F‐region remains poorly understood due to the lack of direct thermospheric neutral wind observations. To address this, we investigate MJO propagation from the E‐region to the F‐region using simulations from the Thermosphere Ionosphere Electrodynamics General Circulation Model (TIE‐GCM) nudged with outputs from the Specified Dynamics Whole Atmosphere Community Climate Model with thermosphere ionosphere Extension (SD‐WACCM‐X). The results show that DE3 amplitudes in F‐region electron density (∼300 km, 15°N) vary by about ∼ 20%. The simultaneous response of E‐region zonal winds, F‐region vertical drifts, and electron density highlights the role of the E‐region dynamo. Controlled simulations reveal that ∼ 73% of DE3 MJO perturbations are transported by vertical drifts, with the remainder by neutral winds. The semidiurnal eastward wave number 2 (SE2) tide contributes about 65% of its variability transmitted via field‐aligned neutral winds. While SE2 plays a secondary role (∼10%, half of DE3), DE3 dominates the tidal variability, emphasizing the E‐region dynamo's control over the ionospheric response. The MJO further modulates zonal mean F‐region electron density by 4%–5%, primarily through semidiurnal westward (SW2) migrating tides. These results highlight how MJO–tide interactions shape ionospheric variability, with potential impacts on satellite drag, navigation, and communication systems.
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This content will become publicly available on December 1, 2026
Tidally Driven Wavenumber‐3 and ‐4 Structures in the Ionosphere‐Thermosphere Observed by ICON and Comparison of Their Coupling Mechanisms
Abstract We analyze fixed local time, longitudinal wavenumber‐3 (WN3) and wavenumber‐4 (WN4) structures in the low‐latitude F‐region ionosphere using ICON‐IVM observations of ion drifts, temperatures, and densities from Jan 2020 to Jun 2022. These ionospheric wave patterns are compared to non‐migrating tides and stationary planetary waves in the Mesosphere and Lower Thermosphere (MLT) zonal winds from ICON‐MIGHTI. We find relative amplitudes of ionospheric WN4 are highly correlated with WN4 in MLT zonal winds (cc = 0.80), and particularly with DE3 (cc = 0.77). WN4 shows the strongest correlation with DE3 near ∼110 km altitude and ∼15° magnetic latitude, where MLT winds are approximately field‐aligned with the ionospheric measurements and E‐region conductivities peak. Phase analysis further supports the E‐region dynamo as the dominant mechanism coupling MLT and ionospheric WN4. In contrast, no such evidence is found for WN3, suggesting alternative coupling mechanisms dominate. The relative amplitudes of ionospheric WN3 show correlations with WN3 in MLT zonal winds but with a weaker coefficient (cc = 0.55, and cc = 0.50 with DE2). Variability in ionospheric WN3 is also significantly influenced by the stationary planetary wave SPW3 (cc = 0.30). To test whether thermospheric composition changes contribute to the generation of ionospheric WN3/4, we correlate O/N2wave amplitudes with ionospheric wave amplitudes. We find a significant correlation between ionospheric and O/N2WN3 (cc = 0.41) but only a weak correlation for WN4 (cc = 0.19) consistent with a greater role for composition‐driven coupling in WN3 than WN4.
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- PAR ID:
- 10680076
- Publisher / Repository:
- AGU Wiley
- Date Published:
- Journal Name:
- Journal of Geophysical Research: Space Physics
- Volume:
- 130
- Issue:
- 12
- ISSN:
- 2169-9380
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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