Three different approaches to the evaluation of the electrostatic potential in the ionosphere under equatorial spread F(ESF) conditions are considered. First, we calculate the potential using an analytical approach, applying force balance laws to a simplified ionosphere. Second, we compute the potential around a cylinder‐like plasma depletion in an idealized ionosphere using both the equipotential field line (EFL) approach and the full 3‐D solution to the electrostatic potential problem. Our third approach involves an initial boundary value simulation in a realistic ionosphere using both EFL and 3‐D potential solutions. The results show that the equipotential field line assumption does not fully capture the 3‐D structure of the ionospheric current system and leads to an underestimation of the growth rate of ESF irregularities in numerical simulations.
