The goal of this project is to advance understanding of the spectrum of large-scale ionospheric electron density irregularities commonly observed in the nighttime equatorial and low-latitude ionosphere, known as Equatorial Spread F (ESF), as a function of varying geophysical conditions. The result will be an improved understanding of the processes responsible for ESF development, variability and morphology. The approach is to use in-situ ion density measurements made by the Planar Langmuir Probe (PLP) onboard the C/NOFS (Communication/Navigation Outage Forecasting System) satellite. The observations made by the C/NOFS-PLP can provide a characterization of the spatial (in the zonal direction) spectrum of large-scale ESF structures under different geophysical conditions. Analysis of the PLP measurements will also make it possible to identify the occurrence of periodic structures, and the occurrence of a dominant wavelength (or a dominant range of wavelengths). PLP measurements will allow the estimation of the occurrence rate of large-scale ESF structures as a function of season and longitude sector. The project will investigate possible explanations for the variability in ESF periodicities.
