Abstract The Madden‐Julian Oscillation (MJO) is the dominant mode of intraseasonal variability in the tropical troposphere and known to affect the tidal activity in the mesosphere and lower thermosphere (MLT). Using Constellation Observing System for Meteorology, Ionosphere, and Climate‐2 (COSMIC‐2) Global Ionospheric Specification electron density data, we show that the MJO impact extends into the F‐region ionosphere. The MJO imposes an average amplitude variability of 15% in the non‐migrating diurnal tide (DE3) and 2%–5% for the migrating diurnal tide (DW1), with significant responses observed in other diurnal and semidiurnal tidal components. Sounding of the Atmosphere using Broadband Emission Radiometry MLT temperature tides shows no time lag to COSMIC‐2. E‐region dynamo is thus the likely the main mechanism that couples the MJO into the ionosphere. Magnitude and ubiquity of the ionospheric MJO signal underlines the relevance of recurring tropospheric weather patterns for understanding the space weather of the ionosphere.
Aggarwal et al. (2025) studied this question.