Thermospheric Neutral Wind Studies Over the Equatorial Region: A Review

Thermospheric neutral winds (TNW) refer to the neutral gases in the thermosphere circulating as tides, which play a crucial role in the dynamics of the thermosphere-ionosphere system (TIS). Global geospace neutral winds, particularly over the magnetic equator, have been a subject of study for several decades. However, despite the known importance of neutral winds, there is still a lack of comprehensive understanding and characterization of the winds. Various ground-based and satellite missions have provided valuable information on the contribution of neutral winds to the global atmospheric dynamics. However, efforts in the global monitoring of neutral winds are still lacking, and the drivers behind TNW behavior as well as their influence on the thermosphere-ionosphere coupled system (TIS) remain incomplete. To address these knowledge gaps in the global circulation of TNW, it is crucial to develop a deep understanding of neutral wind characteristics over different regions. The low latitude equatorial region in particular has been observed to exert complex influences on TNW due to the unique effects of the Earth’s magnetic field at the dip equator. Studying neutral winds over this region will provide valuable insights into the unique dynamics and processes that occur in this region, thereby enhancing our understanding of their role in the overall dynamics of the TIS. Additionally, through empirical observations, an improved ability to accurately model and predict the behavior of this region can be achieved. This review paper addresses challenges in understanding equatorial winds by reviewing historical measurements, current missions, and the interactions of ionospheric and thermospheric phenomena, emphasizing the need for comprehensive measurements to improve global atmospheric dynamics and weather forecasting.