Effect of the spatial and temporal distribution of molecular ions in the ionospheric E-field on the behavior of NmF2 during the geomagnetic storm of March 17–23, 2015

We consider different approaches to calculating the ion composition in the lower ionosphere and use two methods for modeling the concentration of molecular ions. The first method allows us to solve an equation with an effective recombination coefficient for the total concentration of molecular ions, and the second method calculates their concentrations separately. Numerical experiments were performed using a global self-consistent model of the thermosphere, ionosphere, and protonosphere (GSM TIP) for the conditions of March 16–20, 2015. We show that the second method, which provides a more accurate approximation, leads to significant consequences. Due to a strong change in the calculated concentration of ions in the E-region, the conductivity varies thus affecting the qualitative and quantitative behavior of the electric dynamo field at low and equatorial latitudes. Even without mesospheric tides and the electric dynamo field in the F-region, the calculation of partial concentrations of molecular ions makes it possible to qualitatively reproduce the outburst of the eastern electric field observed at the geomagnetic equator and in its low-latitude vicinity. During geomagnetic disturbances, a more accurate approximation leads to significant changes in the pattern of electron density perturbations at the heights of the ionospheric F-region in comparison with that obtained with the calculated total concentration of molecular ions.