Daytime Zonal Drifts in the Ionospheric 150km and E Regions Estimated Using Ear Observations

Multibeam observations of the 150km echoes made using the Equatorial Atmosphere Radar (EAR), located at Kototabang, Indonesia, provide unique opportunity to study both vertical and zonal ExB plasma drifts in the equatorial ionosphere. In this paper, we focus on estimating daytime zonal drifts at the 150km (140-160km) and E (100-110km) regions using multibeam observations of 150km and E region echoes made using the EAR and study the daytime zonal drifts covering all seasons not studied before from Kototabang. Zonal drifts in the 150km and E regions are found to be westward and mostly below -80ms⁻¹ and -60ms⁻¹, respectively. While the zonal drifts in the 150km and E regions do not go hand in hand on a case-by-case basis, the seasonal mean drifts in the two height regions are found to be in good agreement with each other. Zonal drifts at the 150km region show seasonal variations with three maxima peaking around May, September, and January. The zonal drifts at the 150km region are found to be smaller than the F region drifts obtained from Coupled Ion Neutral Dynamics Investigation (CINDI) onboard Communication and Navigation Outage Forecasting System (C/NOFS) by about 25ms⁻¹ consistent with the height variations of F region zonal drifts observed by the Jicamarca radar. These results constitute the first comprehensive study of zonal drifts at the 150km and E regions from Kototabang, Indonesia, and the results are discussed in the light of current understanding on the low-latitude electrodynamics and coupling.