Estimating High Latitude Electrodynamics: Opportunities for Synergy Netween L1-driven Models and Global Observations to Improve Prediction and Specification

Abstract:

The advent of continuous solar wind and interplanetary magnetic field observations with the launches of WIND and ACE opened new opportunities in evaluating the relationships between external driving conditions and high-latitude electrodynamics. Numerous studies attempted to derive optimal parameterizations to estimate the global energy transfer to the magnetosphere. Other analyses of high-latitude potential, Birkeland currents, and auroral precipitation provide a means to estimate an instantaneous state assuming that the statistical distribution approximates the instantaneous state. More recently available global observations of high-latitude electrodynamical parameters, in particular the Birkeland currents from the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE), allow us to examine these statistical pattern techniques to assess their veracity. The availability of global determinations of Birkeland currents with AMPERE allows a hybrid approach in which the patterns are derived using very stable upstream conditions for periods of at least two hours to ensure that the conditions observed at the L1 point correspond as near as possible to those at Earth. The resulting patterns show greater contrast between IMF orientations than the standard approach that uses more precise satellite data but includes all of the L1 observations. These results indicate that the dynamics of the IMF and solar wind, together with intrinsic uncertainties in timing of arrival at Earth from L1 and structure in the interplanetary medium, may fundamentally limit the precision of standard approaches. Using this new approach, analyses can be extended to transitions in the solar wind and IMF to study characteristic dynamics of the magnetospheric response including delays, construction of empirical models of high-latitude electrodynamics for improved near-term forecasting, and how new real-time observations from AMPERE-NEXT might be used to provide new tools for specification.