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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 February 1, 2027
The Ionospheric Lunar Tidal Response to the 2020–2021 Sudden Stratospheric Warming Observed by COSMIC‐2, ICON and Modeled by SD‐WACCMX, TIE‐GCM
Abstract This study examines how the breakdown of the stratospheric polar vortex influences lunar semidiurnal (M2) tides in F‐region electron density using Global Ionospheric Specification (GIS) data from the Constellation Observing System for Meteorology, Ionosphere, and Climate‐2 (COSMIC‐2). During the 2020–2021 Sudden Stratospheric Warming (SSW) event—marked by an exceptionally disrupted polar vortex—we observe up to a 16% enhancement in the M2 lunar tide at low latitudes (equatorial ionization anomaly) around 300 km altitude relative to the mean state. The response of M2 in vertical plasma drifts measured by the ion velocity meter on board the Ionospheric Connection Explorer satellite shows similar variability. Whole‐atmosphere model simulations using the Specified Dynamics Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension (SD‐WACCM‐X) reproduce consistent M2 tidal signatures in E‐region zonal winds, F‐region vertical drifts, and electron density. To quantify the relative contributions of electrodynamics and neutral winds, we analyzed the ion continuity equation using the National Center for Atmospheric Research Thermosphere–Ionosphere–Electrodynamics General Circulation Model with SD‐WACCM‐X as the lower boundary. Results show M2 tides impact F‐region electron densities primarily through vertical plasma drifts, which increase by ∼114% during the SSW, while transport by neutral winds rises by ∼43%. These findings confirm that vertical drifts dominate lunar tide transport, with neutral winds providing a secondary contribution.
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- PAR ID:
- 10680078
- Publisher / Repository:
- AGU Wiley
- Date Published:
- Journal Name:
- Journal of Geophysical Research: Space Physics
- Volume:
- 131
- Issue:
- 2
- ISSN:
- 2169-9380
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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