ABSTRACT

The high-latitude electric field is one of the most important parameters that influence energy deposition in the form of Joule heating in the upper atmosphere. Numerical models often use statistical or climatological electric-field models which ignore an important component of Joule heating that is due to rapid, small-scale fluctuations in the electric field, or small-scale variability (SSV). Studies attempting to quantify this type of variability using satellite or groundbased incoherent scatter radar measurements have created variability maps associated with statistical electric-field patterns. The variability described in these studies is a different type of variability, namely, climatological model variability (CMV) that describes how well the model reproduces the measurements. The relationship between these two variabilities, and the physical significance of CMV, is presently unknown. This project aims to resolve the ambiguity between CMV and SSV by using data from southern and northern hemisphere SuperDARN radars to develop maps of both CMV (similar to previous studies) and SSV. The latter will be obtained from observations sampled at 1-2 min that are continuous for >10 min. The resulting maps will allow for a direct comparison of the relative magnitudes of CMV and SSV over the entire high-latitude region, providing a clear picture of the physical significance of SSV and CMV in electric fields. By further utilizing the widespread and continuous SuperDARN measurements for specific events, the project obtain additional information that allows the variability measurements to be located relative to large-scale convection and magnetospheric boundaries, providing clues to its origins. The end product of the research should be the resolution of the ambiguity that exists between SSV and CMV, and clarification of the physical significance that CMV plays in the high-latitude ionosphere. Since large-scale convection maps of the high-latitude electric potential are perhaps the most commonly used data product of the SuperDARN HF network, the southern hemisphere statistical patterns resulting from this study will improve the accuracy of the southern hemisphere convection patterns during times when data coverage is not widespread. The availability of hemisphere-specific statistical patterns and variability maps resulting from this project will facilitate studies of the interhemispheric dependencies of various ionospheric and magnetospheric parameters.