New Observations of Large-Scale Waves Coupling With the Ionosphere Made by the GOLD Mission: Quasi-16-Day Wave Signatures in the F-Region OI 135.6-nm Nightglow During Sudden Stratospheric Warmings

The recently launched Global-scale Observations of the Limb and Disk (GOLD) Mission observed prominent quasi-16-day oscillations (Q16DOs) in the OI 135.6-nm nightglow from the equatorial ionization anomaly (EIA) region during 26 November 2018 to 25 January 2019. Meanwhile, the enhanced and concurrent quasi-16-day wave (Q16DW) activity was observed in the middle atmosphere by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument. This implies that the F-region ionosphere couples with the lower atmosphere through large-scale waves. A noteworthy phenomenon was that the Q16DOs displayed an asymmetric behavior between the northern and southern EIA crests. This asymmetry indicates that the ionospheric Q16DOs might be driven by the Q16DW-modulated tides, which not only modulated the E-region dynamo winds but also modulated the F-region field-aligned neutral winds via vertical penetration, producing the oscillations in plasmas densities. Plain Language Summary Driving of the short-term variability in the ionosphere is a crucial scientific question of space physics, which connects the thermosphere and ionosphere to the solar and magnetospheric forcing, as well as terrestrial atmosphere weather. It is also the most challenge part of space weather forecast. Traveling planetary waves (PWs), including the eastward propagating Kelvin waves and westward propagating Rossby waves, are responsible for a large amount of day-to-day variability in ionospheric parameters. Our study showed an evidence of the Rossby waves coupling with the nighttime F-region ionosphere observed by GOLD. More importantly, the observations suggested a physical pathway accounting for the PW coupling in the atmosphere-ionosphere system; that is, PW-modulated tides penetrate into the F-region ionosphere and produce the field-aligned motion of the plasmas, leading to the oscillations in electron density at the PW periods.