Model simulation of the equatorial electrojet in the Peruvian and Philippine sectors

Between 100 and 120 km height at the Earth's magnetic equator, the equatorial electrojet (EEJ) flows as an enhanced eastward Current in the daytime E region ionosphere, which can induce a magnetic perturbation on the ground. Calculating the difference between the horizontal components of magnetic perturbation (H) at magnetometers near the equator and about 6-9 degrees away from the equator, Delta H, provides us with information about the strength of the EFJ. The NCAR Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM) is capable of simulating the EEJ current and its magnetic perturbation on the ground. The Simulated diurnal, seasonal (March equinox, June solstice, December solstice), and solar activity (F(10.7) = 80, 140 and 200 units) variations of Delta H in the Peruvian (76 degrees W) and Philippine (121 degrees E) sectors, and the relation of Delta H to the ionospheric vertical drift velocity, are presented in this paper. Results show the diurnal, seasonal and solar activity variations are captured well by the model. Agreements between simulated and observed magnitudes of Delta H and its linear relationship to vertical drift are improved by modifying the standard daytime E region photoionization in the TIE-GCM in order to better simulate observed E region electron densities. (C) 2008 Elsevier Ltd. All rights reserved.