Mesospheric Q2DW interactions with four migrating tides at 53$^circ$N latitude: zonal wavenumber identification through dual-station approaches | CU Experts

Mesospheric winds from two longitudinal sectors at; 53$^circ$N latitude are combined to investigate; quasi-two-days (Q2DWs) and their nonlinear interactions with tides. In a; summer 2019 case study, we diagnose the zonal wavenumber $m$ of; spectral peaks at expected frequencies through two dual-station; approaches, a phase differencing technique (PDT) on individual spectral; peaks and a least-squares procedure on family-batched peaks. Consistent; results from the approaches verify the occurrences of Rossby-gravity; modes ($m$=3 and 4 at periods $T$= 2.1d and 1.7d), and their; secondary waves (SWs) generated from interactions with diurnal,; semi-diurnal, ter-diurnal and quatra-diurnal migrating tides. We further; extend the PDT to 2012$textendash$2019, illustrating; that Q2DWs exhibit significant interannual variability. Composite; analysis reveals seasonal and altitude variations of the Rossby-gravity; modes and their SWs. The Rossby-gravity modes maximize in local summer,; whereas their 16- and 9.6-hr SWs appear more in winter, potentially; originating from Q2DW-tide interactions in the opposite hemisphere.

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