Gravity and Pressure-Gradient Currents Using Ionospheric Electron Density Measurements From COSMIC Satellites

摘要

The gravity-driven and pressure-gradient currents coexist in the ionosphere, and their effects are significant in there, rather than at the outside of the ionosphere; and can be important while studying the ionospheric currents using low-Earth-orbiting (LEO) satellite measurements. Maute and Richmond (2017, https://doi.org/10.1002/2017JA024841) (MR17) have demonstrated that above the F region peak, directions of these two coexisting currents are opposite and the net magnetic effects along the ambient magnetic field are nonsignificant. In the view of the diamagnetic corrections being applied to the LEO magnetic field measurements to account for the pressure-gradient currents, it is imperative to examine the proposition of MR17. In the present paper, we have estimated the gravity and pressure-gradient currents, using altitude profiles of electron density obtained from the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC)-1 satellite cluster. In order to get the latitudinal profiles of magnetic field variations at a fixed local time (LT) using COSMIC data, it is required to combine either different days at a fixed longitude or all the longitudes on a fixed day, thus compromising with either days or longitudes. It is found that the net magnetic field is significant in the low-latitude region, which increases with solar flux and decreases with altitude. The magnetic field effects show strong LT dependence and are significant in the noon to evening sector. The comparison of the present estimates with the diamagnetic corrections emphasizes that correcting for only one current can introduce unviable errors and thus supports the suggestion of MR17.