The objective of this study is to gain a better understanding of the mechanisms of equatorial electrodynamics in the pre-sunrise ionosphere. Strong upward plasma drifts have been observed by satellites and radars in the early morning hours at equatorial latitudes during the recent solar minimum. The investigators will analyze measurements from the C/NOFS satellite and the Jicamarca radar to infer the morphology (local time, longitudinal, and seasonal variations) of the early morning vertical drift. Comprehensive physical models, the Whole Atmosphere Model (WAM), the Global Ionosphere and Plasmasphere model (GIP) and the Thermosphere-Ionosphere-Mesosphere Electrodynamic General Circulation Model (TIME-GCM) will be used to interpret the observations and to investigate the causal mechanisms of the early morning upward drift. The influence of the early morning upward drift on the thermosphere and ionosphere near dawn and in the daytime will also be estimated. The study combines observations, theory and modeling to achieve a better understanding of the dynamics of the upper atmosphere and the physical processes leading to the early morning upward drifts. The results will help improve the prediction of ionospheric irregularities, which cause GPS scintillation and radio communication outages in the equatorial ionosphere.
