Equatorial zonal electric fields inferred from a 3D electrostatic potential model and ground-based magnetic field measurements

We present a new technique to infer quiet-time zonal electric fields in the daytime equatorial ionosphere. The electric field inference technique utilizes a three-dimensional (3D) electrostatic potential model of the low-latitude ionosphere constrained by ground-based magnetic field measurements. To test this technique, inferred zonal electric fields for the Peruvian sector in Jicamarca (11.95 degree S; 283.13 degree E; 0.6 degree N dip latitude) were compared with zonal electric field (vertical drift) measurements made by the Jicamarca Incoherent Scatter Radar (ISR). The comparison shows a good agreement between the inferred and measured electric fields. An example of electric field estimation for Davao (7.4 degree N; 125.4 degree E; 0.58 degree S dip latitude) in the Philippines sector, is also presented in this report. Inferred electric fields for Davao are in good agreement with F region vertical plasma drifts measured by drift sensors onboard the AE-E and ROCSAT-1 satellites on that longitude sector. Our results suggest that realistic estimates of quiet-time zonal electric fields for the equatorial ionosphere can be obtained from the 3D potential model whenever observatory magnetic field measurements are available.