Seasonal and Interannual Variations of Global Tides in the Mesosphere and Lower Thermosphere Neutral Winds: I. Diurnal Tides

Liu, Yangkun; Xu, Jiyao; Smith, A. K.; Liu, Xiao

doi:10.1029/2023ja031887

Cited by 4 publications

(1 citation statement)

References 52 publications

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“…This paper is a continuation of the effort to investigate the seasonal and interannual variations of tidal winds in the MLT. In the companion paper (Liu et al, 2024, hereinafter referred to as Part I), we present the seasonal and interannual variations of diurnal tides in neutral winds. In this paper, we focus on the seasonal and interannual variations of semidiurnal and terdiurnal tides in neutral winds.…”

Section: Introductionmentioning

confidence: 99%

Seasonal and Interannual Variations of Global Tides in the Mesosphere and Lower Thermosphere Neutral Winds: II. Semidiurnal and Terdiurnal Tides

Liu,

Xu,

Smith

et al. 2024

JGR Space Physics

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In the mesosphere and lower thermosphere (MLT) region, semidiurnal and terdiurnal tides are dominant at middle and high latitudes and are important for the dynamics and structures. Using the global neutral horizontal wind data in the MLT region observed by TIMED Doppler interferometer from 2002 to 2021, the seasonal and interannual variations of six semidiurnal and terdiurnal tidal components (SW2, SW3, SW4, TW3, TW2 and TW4) are investigated. Particularly, the responses of these tidal components to the stratospheric quasi‐biennial oscillation (SQBO) and the solar cycle are presented. The results indicate that: (a) seasonal and interannual variations of these tidal components are pronounced in their peak regions. The peak region is defined as the region where the ratio of the annual mean amplitude to the maximum annual mean amplitude is larger than 0.8. (b) In their peak regions, migrating tidal components exhibit strong seasonal variations at annual (annual oscillations (AO)), semiannual (semiannual oscillations (SAO)) and terannual (terannual oscillations (TAO)) periods, whereas nonmigrating tidal components only exhibit prominent AO and SAO. (c) In their peak regions, the responses of the annual mean amplitudes of these tidal components to SQBO are negative; the responses of migrating tidal components to solar cycle are negative whereas those of nonmigrating tidal components are positive. (d) For these tidal components, the responses of the amplitudes of seasonal variations to SQBO and solar cycle are weaker than their annual mean amplitudes, and the latitude × altitude response patterns are not always consistent with those of the annual mean amplitudes.

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Section: Introductionmentioning

confidence: 99%

Seasonal and Interannual Variations of Global Tides in the Mesosphere and Lower Thermosphere Neutral Winds: II. Semidiurnal and Terdiurnal Tides

Liu,

Xu,

Smith

et al. 2024

JGR Space Physics

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Seasonal Dependency of the Solar Cycle, QBO, and ENSO Effects on the Interannual Variability of the Wind DW1 in the MLT Region

Wu,

Ridley,

Cullens

2024

JGR Space Physics

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The migrating diurnal tide (DW1) is derived by fitting Hough Mode Extensions to the TIMED/TIDI near‐global wind measurements within the mesosphere and lower thermosphere between 85 and 100 km from 2004 to 2014. The tidal amplitude peaks around the equinoxes with a large interannual variability of up to 50%. The correlation coefficients between the tidal amplitude variability and the solar cycle as represented by F10.7, stratospheric Quasi‐Biennial Oscillation (QBO), and El Niño‐Southern Oscillation (ENSO) are calculated every 10 days revealing seasonal dependencies. The interannual variability is positively correlated with QBO from spring to fall, maximizing around the equinoxes; anti‐correlated to the solar cycle in early winter; and anti‐correlated to ENSO in early winter and slightly in March. Multivariate linear regressions are performed to quantitatively analyze the linear relationships between the DW1 amplitude and those factors. The fittings perform best with the QBO at 30 and 50 hPa both being considered. The contribution of QBO peaks around January and October may be related to the polar vortex modulated by QBO in the northern and southern hemispheres, respectively. The correlation between the DW1 amplitude and ENSO is negative with time lags <∼5 months during early winter and spring.

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Mechanisms Underlying the Changes in Sporadic E Layers During Sudden Stratospheric Warming

Zheng,

Fang,

Xiao

et al. 2024

Atmosphere

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During sudden stratospheric warming (SSW) events, significant modifications occur, not only in the neutral atmosphere, but also in the ionosphere. Specifically, sporadic E layers in the mesosphere and lower thermosphere regions significantly disrupt satellite communication. Although research has frequently focused on ionospheric alterations during SSW events, detailed studies on sporadic E layers remain limited. Examining these variations during SSW events could enhance our understanding of the interaction mechanisms between the ionosphere and the neutral atmosphere, and provide insights into the patterns of sporadic E layer alterations. This study analyzed the behavior of sporadic E layers during the 2008/2009 winter SSW period using data from three Japanese stations and satellite observations. The principal findings included the following: (1) The enhancement in the critical frequency of the sporadic E layers was most notable following the transition from easterly to westerly winds at 60° N at a 10 hPa altitude, accompanied by quasi 6-day and quasi 16-day oscillations in frequency. (2) The daily average zonal and meridional wind speeds in the MLT region also exhibited quasi 6-day and quasi 16-day oscillations, aligning with the observed periodicities in the critical frequency of the sporadic E layers. (3) Planetary waves were shown to modulate the amplitude of diurnal and semidiurnal tides, influencing the sporadic E layers. Furthermore, a wavelet analysis of foEs data with a time resolution of 0.25 h demonstrated that planetary waves also modulate the frequency of diurnal tides, thereby affecting the sporadic E layers. This research contributes to a deeper understanding of the formation mechanisms and prediction of sporadic E layer behavior.

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Seasonal and Interannual Variations of Global Tides in the Mesosphere and Lower Thermosphere Neutral Winds: I. Diurnal Tides

Cited by 4 publications

References 52 publications

Seasonal and Interannual Variations of Global Tides in the Mesosphere and Lower Thermosphere Neutral Winds: II. Semidiurnal and Terdiurnal Tides

Seasonal and Interannual Variations of Global Tides in the Mesosphere and Lower Thermosphere Neutral Winds: II. Semidiurnal and Terdiurnal Tides

Seasonal Dependency of the Solar Cycle, QBO, and ENSO Effects on the Interannual Variability of the Wind DW1 in the MLT Region

Mechanisms Underlying the Changes in Sporadic E Layers During Sudden Stratospheric Warming

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