Empirical Modeling of the Equatorward Boundary of Auroral Precipitation Using DMSP and DE 2

Abstract

A new model of the equatorward boundary of the diffuse aurora has been developed using observations of precipitating particles made by the Defense Meteorological Satellite Program (DMSP) from 1987 to 2012 as well as Dynamics Explorer 2 (DE 2), which operated from August 1981 to February 1983. Using a local multilinear regression algorithm, we investigated the use of different combinations of magnetometer indices and solar wind coupling functions with different averaging periods and weights to find the best parameterization for a model of the equatorward boundary of the aurora. We find that weighted averages of the AE index and the solar wind coupling function dΦ MP /dt both outperform the often used Kp index. Using conjunction events where two DMSP satellites cross the auroral boundary at nearly the same time, we show that these models are better at extrapolating the auroral boundary to different local times than previous models.This function is derived such that it is proportional to the rate that magnetic flux is opened at the magnetopause. The equatorward boundary of the diffuse aurora is of particular interest when characterizing subauroral electric fields, such as subauroral ion drifts (Yeh et al., 1991) or subauroral polarization streams (Foster & LANDRY AND ANDERSON 2072 Key Points: • Models of the equatorward auroral boundary parameterized by AE and the solar wind coupling function dΦ MP /dt outperform a Kp-based model • Both the AE and dΦ MP /dt models show a seasonal variation not seen when parameterizing by Kp • The two new boundary models outperform previous models at extrapolating the auroral boundary latitude from a single determination

Statistical Analysis of the Main Ionospheric Trough Using Swarm in Situ Measurements

“…In our study, at nighttime and in the early morning, the troughs are located in lower latitudes that below the auroral oval. However, the equatorward boundary of the dayside auroral oval can be highly scattered and blurred in the satellite data, and there are considerable differences between different auroral models' location of this boundary (e.g., Carbary, ; Hardy et al, ; Landry & Anderson, ; Sotirelis & Newell, ; Spiro et al, ). It can be derived from these models that the typical equatorward boundary of the auroral oval during the daytime (09–15 MLT) vary between 70° and 75°, which is almost collocated with the dayside trough positions in our results.…”

A Comparison of Auroral Oval Proxies With the Boundaries of the Auroral Electrojets

“…Using satellite based FUV images and measurements of particle precipitation, previous studies have investigated how season affects the auroral oval (Oznovich et al., 1993), the OCB (Laundal et al., 2010), and the equatorward boundary of the diffuse aurora (Landry & Anderson, 2019). In this section we investigate how the different boundary data sets used in this study vary with season.…”

Occurrence of Large Geomagnetically Induced Currents Within the EPRI SUNBURST Monitoring Network

“…Since most of the United States power grid is located in the higher mid‐latitudes to the low‐latitudes, the absence of events around local midnight indicates that auroral substorms are not likely to be a driving source. However, it should be noted that auroral activity can sometimes produce large GICs in mid‐low latitudes during extreme geomagnetic storms as the auroral current can extended into those regions (Ngwira et al., 2013, 2015; Weygand et al., 2023). Case study #2 in the present paper highlights one of such cases of auroral activity driving GICs at mid‐latitudes.…”

“…The SECS technique has been widely applied in the study of GMDs (Engebretson et al., 2021; Ngwira et al., 2018; Oliveira et al., 2021; Weygand et al., 2016). The current version of SECS ingests 10‐s magnetometer data from ground networks across North America and Greenland but can be run at other resolutions (Weygand et al., 2023). Maps of dB/dt distribution pattern computed from the SECS interpolated magnetic field are presented in Figure 7 (left) at three different time steps.…”