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Ionospheric currents and their associated magnetic perturbations
In the last several decades Low Earth Orbit (LEO) satellites have provided extensive magnetic measurements to advance our understanding of the complex ionospheric current system. Interpreting the measured magnetic field and its associated current is still challenging since the measured magnetic field reflects the influence of various current sources. At high latitude ionospheric currents are mainly driven by the magnetosphere-ionosphere coupling through ion convection and field-aligned current. At mid- and low latitude the collisional interaction between thermospheric winds and ions is important and sets up electric fields and currents. Smaller low latitude current is produced by gravity and plasma pressure gradient forces. Although the latter currents are weak they can produce persistent 5-7 nT perturbations at LEO altitudes in regions of enhanced plasma as in the equatorial anomaly region, and its effect can last into the evening. Knowledge about the characteristics of these currents and their associated magnetic perturbation is important for studies analyzing day and evening low latitude LEO magnetic perturbations.
Numerical simulations of the ionospheric current system can support the LEO magnetic measurement interpretation. In this presentation we will introduce a numerical model capable of calculating the 3D ionospheric current system and its associated magnetic perturbation at LEO altitude due to the wind dynamo, the magnetospheric field-aligned current, and gravitational and pressure gradient forces. We will apply this model to study effects of the wind dynamo in the E- and F-region. The model will be used to examine the current system and the magnetic perturbations associated.