Three‐dimensional nonlinear evolution of equatorial ionospheric spread‐F bubbles

Abstract

Using numerical simulation techniques, we present the first study of the three‐dimensional nonlinear evolution of an equatorial spread‐F bubble. The background ionosphere used to initialize the bubble evolution is computed using a time‐dependent first‐principles equatorial plasma fountain model together with a prereversal enhancement vertical drift model. We find that finite parallel conductivity effects slow down both the linear and nonlinear bubble evolution compared to the two‐dimensional evolution. In addition we find that bubble‐like structures with extremely sharp density gradients can be generated off the equator at equatorial anomaly latitudes in agreement with recent observations.