DOI: 10.5281/zenodo.18081565
title: Dataset for "Atmospheric Tide Amplitudes and Their Dependence on QBO and ENSO Phases: Insights from MUAM Ensemble Simulations"

description: Research data for the article "Atmospheric Tide Amplitudes and Their Dependence on QBO and ENSO Phases: Insights from MUAM Ensemble Simulations" by Koval A.V., Didenko K.A., Ermakova T.S., Eswaraiah, S., Fadeev A.S., Savenkova E.N., Shnaider A.V., Sokolov A.V.

Abstract. This study examines the dependence of tide amplitudes in the upper atmosphere on long-period tropical oscillations, specifically the Quasi-Biennial Oscillation (QBO) of zonal wind in the equatorial stratosphere and the El Nino–Southern Oscillation (ENSO). Numerical simulations of global atmospheric circulation are performed with the nonlinear mechanistic Middle and Upper Atmosphere Model (MUAM) for different combinations of QBO/ENSO phases. The structures of migrating and non-migrating diurnal and semidiurnal tides are calculated. The analysis focuses on boreal winter (January–February), when planetary waves (PWs) reach peak activity and contribute to the nonlinear generation of non-migrating tides. The results demonstrate, in particular, that the migrating diurnal westward propagationg tide (DW1) is amplified during the westerly QBO phase (wQBO) and under La Nina conditions. For the semidiurnal migrating tide (SDW2), ENSO effects are found to be more pronounced than those of the QBO. During El Nino, the tide’s amplitude decreases in the equatorial region while increasing to the North and South of it, regardless of the QBO phase. Changes in non-migrating tides differ from those of migrating tides with similar periods, which is attributed to the altered wave activity of the stationary PW with zonal wave number 1 (SPW1). The effect of strengthening/weakening of non-migrating diurnal westward propagating tide (DW2) generation for different combinations of QBO/ENSO is demonstrated explicitly by considering the terms responsible for the nonlinear interaction of PW1 and DW1 in the balance equation of perturbed potential enstrophy. Idealized simulations isolating the effects of QBO and ENSO, allowed for the differentiation of the influences of these two oscillations. Such separation is difficult with observational data, where limited time series restrict sample size and reduce statistical power to distinguish between these closely related phenomena.

Results of numerical modeling of atmospheric circulation and calculation of atmospheric tides based on ensemble simulations for different QBO/ENSO phases:

Files marked "LAe", "LAw", "ELe", "ELw" refer to La Nina+easterly QBO, La Nina+westerly QBO, El Nino+easterly QBO, El Nino+westerly QBO, respectively.Files marked "ALL" refer to mean climate values.Files ending with "disp" contain standard deviations of the differences of the corresponding values for calculating statistical significance (see .gs files below). Please, see respective .ctl files w1_tp1_EL_we_disp.ctl, w1_gh1_EL_we_disp.ctl

Files gh_..._jf4.dx and tp_..._jf4.dx contain amplitudes and phases of eastward/westward travelling tides/PWs having periods of 0.5, 1, 5 and 10 days (for znoam wavenumber m=1) and 0.5, 1, 4 and 7 days (for m=2). (Please, see respective .ctl file w1_gh1_EL_e.ctl)Files marked "m1" and "m2" refer to tidal/PW amplitudes and phases with zonal wavenumbers of 1 and 2, respectively. "gh" and "tp" refer to geopotential height (m) and temperature (K).

Files beginning with "uq_vwres__" contains Eliassen-Palm vectors and EP flux divergence. The files are named in the same way. See uqep_vwres_EL_e.ctl for the structure information.