Quasi‐6‐Day Wave Effects on the Equatorial Ionization Anomaly Over a Solar Cycle

Yamazaki, Yosuke

doi:10.1029/2018ja026014

Cited by 36 publications

(59 citation statements)

References 42 publications

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“…Such enhanced wave activity is not present in the eastward propagating ZW1 component (Figure b) or other components with higher ZWs (not shown here). Although studies have found that the amplitude of the Q6DW in the middle atmosphere is greatest during equinoctial months (Forbes & Zhang, ; Qin et al, ; Yamazaki, ), the wave enhancement in September 2019 was exceptional, with the maximum amplitude larger than 0.4 km in the lower thermosphere, which is much larger than the climatological amplitude (0.15 km) or amplitudes recorded during other individual years during 2004–2018 (Figure d). Thus, the large‐amplitude Q6DW observed in September 2019 cannot be explained merely as a seasonal effect.…”

Section: Resultssupporting

confidence: 90%

“…In this way, the Q6DW can affect the

F

region plasma density, as first revealed in the 1990s by ionosonde measurements (e.g., Apostolov et al, ; Altadill & Laštovička, ; Laštovička, ). More recent studies based on global TEC maps have established that the Q6DW effect on the plasma density is largest in the afternoon local time sector near the equatorial ionization anomaly crests (

\pm

20° magnetic latitudes) (Gu et al, , ; Qin et al, ; Yamazaki, ).…”

Section: Resultsmentioning

confidence: 98%

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September 2019 Antarctic Sudden Stratospheric Warming: Quasi‐6‐Day Wave Burst and Ionospheric Effects

Yamazaki

Matthias

Miyoshi

et al. 2020

Geophysical Research Letters

115

138

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An exceptionally strong stationary planetary wave with Zonal Wavenumber 1 led to a sudden stratospheric warming (SSW) in the Southern Hemisphere in September 2019. Ionospheric data from European Space Agency's Swarm satellite constellation mission show prominent 6‐day variations in the dayside low‐latitude region at this time, which can be attributed to forcing from the middle atmosphere by the Rossby normal mode “quasi‐6‐day wave” (Q6DW). Geopotential height measurements by the Microwave Limb Sounder aboard National Aeronautics and Space Administration's Aura satellite reveal a burst of global Q6DW activity in the mesosphere and lower thermosphere during the SSW, which is one of the strongest in the record. The Q6DW is apparently generated in the polar stratosphere at 30–40 km, where the atmosphere is unstable due to strong vertical wind shear connected with planetary wave breaking. These results suggest that an Antarctic SSW can lead to ionospheric variability through wave forcing from the middle atmosphere.

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Section: Resultssupporting

confidence: 90%

“…In this way, the Q6DW can affect the

F

\pm

20° magnetic latitudes) (Gu et al, , ; Qin et al, ; Yamazaki, ).…”

Section: Resultsmentioning

confidence: 98%

September 2019 Antarctic Sudden Stratospheric Warming: Quasi‐6‐Day Wave Burst and Ionospheric Effects

Yamazaki

Matthias

Miyoshi

et al. 2020

Geophysical Research Letters

115

138

View full text Add to dashboard Cite

show abstract

“…The relative amplitude is used to eliminate the influences of seasonal (Figure 1d) and diurnal (Figure 1e) variations of background ionosphere. Relative amplitude is more intimately related to the Q6DW amplitude in the neutral atmosphere (Gu et al, 2018; Yamazaki, 2018), while the absolute amplitude is influenced more by the ambient ionosphere. The strongest ionospheric Q6DO in the relative amplitude accounts for ~17% of the background TEC at 12 LT.…”

Section: New Characteristics Of Ionospheric Responses To the Q6dwmentioning

confidence: 99%

Local‐Time and Vertical Characteristics of Quasi‐6‐Day Oscillation in the Ionosphere During the 2019 Antarctic Sudden Stratospheric Warming

Lin

Rajesh

et al. 2020

Geophysical Research Letters

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This study investigates new characteristics of ionospheric modulations driven by quasi-6-day wave (Q6DW) burst following a rare Antarctic sudden stratospheric warming (SSW) in September 2019. Local-time and vertical variations of the amplitude and phase of quasi-6-day oscillation (Q6DO) in the ionosphere are examined by using data assimilation analysis of electron density from three-dimensional Global Ionosphere Specification (GIS). The maximum amplitudes of Q6DO are located symmetrically ±20°o ff the magnetic equator at~12 LT, with a secondary peak at 17 LT. The amplitude of Q6DO weakens at 15 LT, with a sudden phase shift, suggesting multiple dynamo processes driving the Q6DO-related ionospheric variations. The altitude-latitude structure of Q6DO shows that the ionospheric modulations extend beyond the equatorial ionization anomaly, indicating the wind dynamo source regions at higher latitudes. A likely physical mechanism is discussed based on possible interactions of Q6DW and semidiurnal migrating tides leading to the dynamo modulation and phase differences. Plain Language Summary Sudden stratospheric warming (SSW) is an extreme meteorological phenomenon in the polar stratosphere, which usually occurs in the Northern Hemisphere. Numerous studies have shown that the SSW can significantly disturb the entire atmosphere from the troposphere all the way to the upper thermosphere and ionosphere. In September 2019, a rare and record-breaking SSW occurred in the Antarctic region, providing an opportunity to investigate the ionospheric variabilities connected to the Antarctic SSW, which is seldom explored. In this study, we present observations of the time evolution and vertical structure of quasi-6-day oscillation (Q6DO) in the ionosphere generated from the unusually large quasi-6-day wave (Q6DW) in the mesosphere and lower thermosphere. Our results show that the observed Q6DO behavior in the ionosphere is quite different from climatological characteristics in the local time and vertical structure, which indicates that the coupling mechanisms driving the ionospheric variability are complex due to the presence of Antarctic SSW.

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“…The Q6DW has recently received elevated attention in the literature due to its demonstrated effectiveness in driving F‐region ionospheric variability (Gan et al, , ; Gu et al, ; Gu, Liu, et al, ; Gu, Ruan, et al, ; Qin et al, ; Yamazaki, ). Changes in F‐region electron densities at Q6DW periods result from transport by ExB drifts, where the electric field E is generated in the ionospheric E‐region through dynamo action of Q6DW winds and possibly Q6DW modulation of tides and/or gravity waves (e.g., Forbes, ; Meyer, ).…”

Section: Introductionmentioning

confidence: 99%

Planetary Wave (PW) Generation in the Thermosphere Driven by the PW‐Modulated Tidal Spectrum

2020

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The National Center for Atmospheric Research thermosphere-ionosphere-electrodynamics general circulation model (TIE-GCM) is used to conduct numerical experiments that isolate and elucidate a substantial modification of the quasi-6-day wave (Q6DW) above 110 km due to presence of the planetary wave (PW)-modulated tidal spectrum. A two-stage nonlinear tidal interaction is proposed, and its role in vertical coupling by the Q6DW is quantified. The theory enables calculation of net Q6DW accelerations and heating rates in the height-latitude domain (90-300 km; ±75 • ) due to wave-wave interactions of up to 10 ms −1 day −1 and 8 K day −1 , respectively. The Global-Scale Wave Model (GSMW) is used to demonstrate that these forcings produce Q6DW zonal and meridional wind amplitudes, and temperatures, of order 5-20 ms −1 , 5-15 ms −1 , and 5-10 K, respectively. Notably, Q6DW thermal forcing in the GSWM accounts for near-doubling of the wind magnitudes calculated with momentum forcing alone. The computed values are comparable to the 10-22 ms −1 , 3-12 ms −1 , and 4-12 KQ6DW amplitudes calculated with lower-boundary forcing of the Q6DW also included. The proposed two-stage interaction plausibly impacts other PW wind structures in the dynamo region and thus how PW in general participate in atmosphere-ionosphere coupling.

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Quasi‐6‐Day Wave Effects on the Equatorial Ionization Anomaly Over a Solar Cycle

Cited by 36 publications

References 42 publications

September 2019 Antarctic Sudden Stratospheric Warming: Quasi‐6‐Day Wave Burst and Ionospheric Effects

September 2019 Antarctic Sudden Stratospheric Warming: Quasi‐6‐Day Wave Burst and Ionospheric Effects

Local‐Time and Vertical Characteristics of Quasi‐6‐Day Oscillation in the Ionosphere During the 2019 Antarctic Sudden Stratospheric Warming

Planetary Wave (PW) Generation in the Thermosphere Driven by the PW‐Modulated Tidal Spectrum

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