Impact of the Madden‒Julian Oscillation on Mesospheric Migrating Diurnal Tides Observed by Multiple Equatorial Meteor Radars

In this study, we report the response of migrating diurnal tides (DW1) in the mesosphere and lower thermosphere (MLT) region to the Madden‒Julian oscillation (MJO). The DW1 amplitudes are decomposed from the neutral horizontal wind observed by four meteor radars in the equatorial region. The DW1 and zonal wind in the equatorial MLT region show consistent intraseasonal variations, implying that the upward propagating DW1 can affect the mesospheric zonal wind. By jointly analyzing the real-time multivariate MJO (RMM) indices and mesospheric DW1, we found that DW1 responds strongly to the MJO during both boreal winter (difference relative to seasonal means: ∼20%–25%) and summer (∼25%). The MJO convection affects the mesospheric DW1 by modulating the solar radiative absorption by water vapor and latent heat release in the troposphere. The seasonal difference in DW1–MJO response can be attributed to a slight weakening of the DW1 tidal heating sources during MJO phases 1–4 and a significant enhancement during phases 6–7 during summer, driven by the moisture transport from the Indian Ocean and Pacific to the East Asian continent. This finding provides an opportunity to the understanding of the coupling between the troposphere and the mesosphere through migrating tides.

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