An Improved Estimation of SuperDARN Heppner‐Maynard Boundaries Using AMPERE Data

Abstract

Super Dual Auroral Radar Network (SuperDARN) ionospheric convection maps are a powerful tool for the study of solar wind-magnetosphere-ionosphere interactions. SuperDARN data have high temporal (approximately minutes) and spatial (∼45 km) resolution, meaning that the convection can be mapped on fine time scales that show more detail than the large-scale changes in the pattern. The Heppner-Maynard boundary (HMB) defines the low-latitude limit of the convection region, and its identification is an essential component of the standard SuperDARN convection mapping technique. However, the estimation of the latitude of this boundary is dependent on ionospheric scatter availability. Consequentially it is susceptible to nonphysical variations as areas of scatter in different latitude and local time regions appear and disappear, often due to changing propagation conditions. In this paper, the HMB is compared to an independent field-aligned current data set from the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE). A linear trend is found between the HMB and the boundary between the AMPERE Region 1 and Region 2 field-aligned currents in the Northern Hemisphere, at both solar minimum and solar maximum. The use of this trend and the AMPERE current data set to predict the latitude position of the HMB is found to improve the interpretation of the SuperDARN measurements in convection mapping.Both the convection and FAC patterns are a barometer for the state of the coupled magnetosphereionosphere system. Like the convection pattern, the FAC pattern will expand and contract in response to

HMB Variations Measured by SuperDARN During the Extremely Radial IMFs: Is the Coupling Function Applicable in Radial IMF?

“…The distribution peaks in this work are 63° and 64° for antisunward and sunward radial IMF, respectively. Essentially, our results basically agree with the previous findings of HMB variations (Fogg et al., 2020; Imber et al., 2013a).…”

“…This criterion is identical to that in Imber et al (2013a). Besides, the estimation of the HMB latitude is limited to a minimum of 50° and a maximum of 75°, it may lead to the cluster of outliers of HMB latitude at 50° (e.g., Fogg et al, 2020). Thus, we remove the HMB latitude at 50° or 75° MLAT.…”

Super Dual Auroral Radar Network Expansion and Its Influence on the Derived Ionospheric Convection Pattern

“…It is however worth noting that the fitting by Fogg et al. (2020) does not include mid‐latitude data and their fitting stops at 55°, so further analysis is necessary, which will be the subject of a future study.…”

The Evolution of Long‐Duration Cusp Spot Emission During Lobe Reconnection With Respect to Field‐Aligned Currents

“…All available radar data have been processed using the SuperDARN software FitACF, Version 3.0, using the Radar Software Toolkit 4.2 (SuperDARN Data Analysis Working Group et al, 2018), and assimilated using the map potential technique (Ruohoniemi & Baker, 1998). A new method to refine the latitude selection of the Heppnard-Maynard boundary that defines the lower limit in latitude of ionospheric convection has been employed, by using AMPERE data to derive a proxy for the boundary between the Regions 1 and 2 currents (Fogg et al, 2020). Vectors with speeds of less than 100 m s −1 are not considered in our analysis here.…”