The Influence of Atmospheric Tides on the Variability of the Mesosphere–Thermosphere–Ionosphere

This paper is a collaborative effort that originated at the International Space Science Institute Workshop on “Physical Links between Weather and Climate in Space and the Lower Atmosphere” held on January 22-26, 2024. Our goals are to survey the role of tides in facilitating the coupling of the lower and upper atmosphere and identify pathways forward that address challenges to our current understanding. To that end, we provide a brief review of the physics of atmospheric tides and the sources of their day-to-day and seasonal variability during quiet geomagnetic conditions. We identify the mechanisms that couple vertically propagating atmospheric tides to variations in thermosphere–ionosphere wind, composition, and plasma. Each process is punctuated with examples showcasing state-of-the-art observations or models, and requirements for scientific progress. A recurrent theme is a thermospheric measurement gap region between 100 and 200 km that precludes direct observations of tidal vertical coupling processes and their day-to-day variability.