Modeling and analysis of artificial periodic inhomogeneities in the ionosphere

The artificial periodic inhomogeneity (API) technique is an ionospheric modification experiment that creates perturbations in the electron plasma density, studied through the scattering of probing radio waves. This work presents the first comprehensive observation of API irregularities at the HAARP facility including responses from the D, E, and F regions. The measurements were obtained by reprocessing backscatter echoes from an experimental campaign in 2014. To investigate the evolution of these structures, we extend a one-dimensional fluid model previously developed by Hysell and Rojas (2023, https://doi.org/10.1029/2023rs007710), that simulates the formation of API in the E region, incorporating mechanisms that dominate the API formation in other regions. The creation of these irregularities in the D region is accomplished by including a simplified chemical model that contains the reactions necessary for the production of negative ions. In the F region, we consider the inclusion of the ponderomotive force, which is proposed as the primary mechanism to generate these inhomogeneities. The updated model successfully produced API irregularities in the three distinct ionospheric regions according to their respective formation mechanisms. Information about the diffusion process of these structures is obtained by analyzing their decay times.