Statistical characteristics of small‐scale spatial and temporal electric field variability in the high‐latitude ionosphere

Abstract

The statistical characteristics of small‐scale spatial and temporal electric field variability in the high‐latitude regions of Earth's ionosphere are investigated using 48 months of data from the Super Dual Auroral Radar Network (SuperDARN) radars in both hemispheres. Electric field fluctuations on spatial scales between 45 km and 450 km and on temporal scales between 2 min and 20 min are considered. It is found that both the distribution shapes and scale‐size dependencies of the fluctuations are consistent with the expected properties of a turbulent flow. The observed spatial and temporal variability is influenced primarily by the magnitude of the shear or gradient in the background plasma drift and by season and solar cycle, suggesting plasma instabilities and gradients in the conductance as sources of the electric field variability. The relationship between spatial and temporal variability is investigated and it is found that the fluctuations are likely to be a mixture of convecting static and time‐varying structures. It is also observed that the small‐scale variability has statistical characteristics that are very similar in the two hemispheres. For practical purposes, although a stretched exponential function best matches the data, the distribution of observed electric field fluctuations can be approximated using an exponential function, enabling straightforward generation of nearly realistic random fluctuations.