Coupling of Earth's ionosphere and upper-atmosphere (thermosphere) is understood to be dominated by processes occurring in daytime, when ion densities are greatest. The clearest signature of this coupling is the equatorial ionospheric anomaly (EIA), two bands of dense ionospheric plasma straddling Earth's magnetic equator. These bands are produced through the upward transport of plasma by wind-driven dynamo electric fields. A NASA "Explorer" has been selected for study, the Neutral-Ion Coupling Explorer (NICE), with the goal to understand the coupling of energy and momentum in this region of geospace using a novel combined in-situ/remote observational approach. The focus of this study is on low latitudes for the recent finding of strong zonal variability in the EIA that changes over time. These changes are synchronous with variations in the amplitude of atmospheric tides that originate from tropospheric sources. Ionospheric/thermospheric variability on hourly, daily, and seasonal timescales will be directly measured by NICE to elicit the sources and neutral-ion interactions that drive temporal and spatial density variability. Further gains may also be made with inclusion of other space- and ground-based datasets, particularly those provided by the Global Observations of Limb and Disk: GOLD mission, an ultraviolet imaging mission also currently under study by NASA. GOLD will carry an imaging spectrograph to geosynchronous orbit to retrieve temperatures and composition of the upper atmosphere, and would both complement and benefit significantly from in-situ observations by NICE.