Generation of secondary waves arising from nonlinear interaction between the quasi 2 day wave and the migrating diurnal tide

Abstract

Theory and past observations have provided evidence that atmospheric tides and other global‐scale waves interact nonlinearly to produce additional secondary waves throughout the space‐atmosphere interaction region. However, few studies have investigated the generation region of nonlinearly generated secondary waves, and as a result, the manifestation and impacts of these waves are still poorly understood. This study focuses on the nonlinear interaction between the quasi 2 day wave (2dayW3) and the migrating diurnal tide (DW1), two of the largest global‐scale waves in the atmosphere. The fundamental goals of this effort are to characterize the forcing region of the secondary waves and to understand how it relates to their manifestation on a global scale. First, the Fast Fourier Synoptic Mapping method is applied to Thermosphere Ionosphere Mesosphere Energetics and Dynamics‐Sounding of the Atmosphere using Broadband Emission Radiometry satellite observations to provide new evidence of secondary waves. These results show that secondary waves are only significant above 80 km. The nonlinear forcing for each secondary wave is then computed by extracting short‐term primary wave information from a reanalysis model. The estimated nonlinear forcing quantities are used to force a linearized tidal model in order to calculate numerical secondary wave responses. Model results show that the secondary waves are significant from the upper mesosphere to the middle thermosphere, highlighting the implications for the atmosphere‐space weather coupling. The study also concludes that the secondary wave response is most sensitive to the nonlinear forcing occurring in the lower and middle mesosphere and not coincident with the regions of strongest nonlinear forcing.

Ionospheric Variability Due to Tides and Quasi‐Two Day Wave Interactions

“…The vertical and latitudinal structures of the secondary waves generated by the nonlinear interaction between DW1 and 48 hr W3 QTDW are shown in Figure . The 16 hr W4 wave (Figures a, c, and e) is twice (or even larger) as strong as the 48 hr E2 wave, which is similar to the results presented by Chang et al () and Nguyen et al (). The zonal and meridional winds of the 16 hr W4 show stronger amplitudes of 35–40 m/s at ~30–40°S and weaker amplitudes of ~15 m/s at ~30°N.…”

“…The zonal and meridional winds of the 16 hr W4 show stronger amplitudes of 35–40 m/s at ~30–40°S and weaker amplitudes of ~15 m/s at ~30°N. Besides, the meridional wind of 16 hr W4 also shows a third amplitude of 20 m/s at the equator, which agrees well with that from Global Scale Wave Mode (Nguyen et al, ). Besides, the meridional wind amplitude for 16 hr W4 is ~10 m/s at ~20°N, which agrees with the meteor radar observations (Huang et al, ).…”

Climatology and Anomaly of the Quasi‐Two‐Day Wave Behaviors During 2003–2018 Austral Summer Periods

“…The W2 QTDW peaks higher than both W3 and W4 modes, and the W4 QTDW peaks at the lowest height. These features have also been reported many times in previous literatures (Gu, Li, Dou, Wu, et al, ; Huang et al, ; Moudden & Forbes, ; Nguyen et al, ; Pancheva et al, ; Tunbridge et al, ; Wang et al, ). The vertical and latitudinal structures of the W2 and W4 amplitudes do not show clear anomalies from year to year, and thus, we will focus on the anomalies of the W3 QTDW next.…”

Wave coupling from the lower to the middle thermosphere: Effects of mean winds and dissipation

“…This could be explained by nonlinear interactions occurring at lower heights. As reported by Nguyen et al [], secondary waves propagate vertically away from the generation region (e.g., mesosphere) as independent waves and are affected by dissipation and mean winds differently than the primary waves. The modulation of DE3 by the 3 day UFKW is also evident in the time series of DE3 (see Figures a and ), where a clear 3 day modulation can be seen both at 110 km and 260 km.…”