The auroral ionosphere TEC response to an interplanetary shock

Abstract

AbstractThis letter investigates the global total electron content (TEC) response in the auroral ionosphere to an interplanetary shock on 8 March 2012, using GPS TEC data from three pierce point chains. One is a longitudinal chain along ~65° magnetic latitude (MLAT) from ~19 magnetic local time (MLT) through dayside to 03 MLT clockwise; one meridional chain is around 14 MLT from 88° to 59° MLAT; and the third one is a chain along ~75° MLAT from ~14 to 00 MLT clockwise. The first chain clearly presents a TEC signal propagation away from ~14 MLT, indicating the shock impact location. Such a propagation is well consistent with the diffuse shock aurora propagation, and the impact location is well predicted by the shock normal direction calculated using the Geotail solar wind and interplanetary magnetic field data. The meridional chain reveals a very fast TEC signal equatorward expansion at ~45 km/s, which is the manifestation of the shock impact and further compression near the subsolar magnetopause. While TEC along the high‐latitude chain varies randomly, lacking any pattern, it is consistent with the discrete aurora dynamics along the poleward boundary of the auroral oval. These findings strongly support the shock aurora mechanisms of adiabatic compression and field‐aligned current establishment or enhancement, suggest that due to the same mechanisms a shock‐generated TEC variation is a “duplication” of the shock aurora from the global picture to the auroral forms and their dynamics, and open the door for the TEC to be an important tool to understand the solar wind and geospace coupling. These results, for the first time, reveal the prompt, intense, and global ionospheric TEC response to the interplanetary fast‐forward shock.