Mapping high‐latitude ionospheric electrodynamics with SuperDARN and AMPERE

Abstract

An assimilative procedure for mapping high-latitude ionospheric electrodynamics is developed for use with plasma drift observations from the Super Dural Auroral Radar Network (SuperDARN) and magnetic perturbation observations from the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE). This procedure incorporates the observations and their errors, as well as two background models and their error covariances (estimated through empirical orthogonal function analysis) to infer complete distributions of electrostatic potential and vector magnetic potential in the high-latitude ionosphere. The assimilative technique also enables objective error analysis of the results. Various methods of specifying height-integrated ionospheric conductivity, which is required by the procedure, are implemented and evaluated quantitatively. The benefits of using both SuperDARN and AMPERE data to solve for both electrostatic and vector magnetic potentials, rather than using the data sets independently or solving for just electrostatic potential, are demonstrated. Specifically, solving for vector magnetic potential improves the specification of field-aligned currents (FACs), and using both data sets together improves the specification of features in regions lacking one type of data (SuperDARN or AMPERE). Additionally, using the data sets together results in a better correspondence between large-scale features in the electrostatic potential distribution and those in the FAC distribution, as compared to using SuperDARN data alone to infer electrostatic potential and AMPERE data alone to infer FACs. Finally, the estimated uncertainty in the results decreases by typically ∼20% when both data sets rather than just one are included.

Modes of high‐latitude auroral conductance variability derived from DMSP energetic electron precipitation observations: Empirical orthogonal function analysis

“…EOFs of the Hall and Pedersen conductances, herein represented using the polar cap spherical harmonics basis, are obtained by a sequential nonlinear regression analysis of observations along DMSP satellite trajectories and ordered by their variance. These EOFs and their amplitudes can be used to describe the spatial and temporal coherence of the Pedersen and Hall conductances in a manner similar to that reported by Matsuo et al [, ] and Cousins et al [, ] for electric field variability and Cousins et al [, ] for field‐aligned current variability. Our results allow for improved modeling of the background error covariance needed for ionospheric assimilative procedures [ Richmond and Kamide , ; Matsuo et al , ].…”

High‐latitude ionospheric conductivity variability in three dimensions

“…Such specification is important because electric fields and currents are a large source of energy and momentum for the upper atmosphere and is an area where data assimilation has been particularly effective in addressing shortcomings of global models [Matsuo et al, 2005;Cousins et al, 2013aCousins et al, , 2015McGranaghan et al, 2016]. Such specification is important because electric fields and currents are a large source of energy and momentum for the upper atmosphere and is an area where data assimilation has been particularly effective in addressing shortcomings of global models [Matsuo et al, 2005;Cousins et al, 2013aCousins et al, , 2015McGranaghan et al, 2016].…”

“…Our EOFs will support global modeling of 3-D ionospheric electrodynamics. Such specification is important because electric fields and currents are a large source of energy and momentum for the upper atmosphere and is an area where data assimilation has been particularly effective in addressing shortcomings of global models [Matsuo et al, 2005;Cousins et al, 2013aCousins et al, , 2015McGranaghan et al, 2016]. Quantifying ionospheric conductivity variability supports uncertainty estimation for constraining 3-D data assimilative analyses in the same manner that McGranaghan et al [2016] used two-dimensional (2-D) conductance EOFs to constrain 2-D ionospheric electrodynamics analyses.…”

Validity Study of the Swarm Horizontal Cross‐Track Ion Drift Velocities in the High‐Latitude Ionosphere

“…They are based on measurements from single or multiple, space-or ground-based instruments. In addition, analytical (Heelis et al, 1982;Rich & Maynard, 1989;Volland, 1978) and data-driven (Cousins et al, 2015;Richmond, 1992;Richmond & Kamide, 1988) models have also been developed.…”