Ionospheric responses over the Antarctic region to Intense Space Weather events: Plasma Convection vs. Auroral Precipitation

TL;DR

The paper investigates ionospheric TEC responses over the Antarctic during six intense geomagnetic storms in 2023, aiming to disentangle the roles of plasma convection and auroral precipitation. It integrates GPS TEC measurements from Antarctic stations with SuperDARN convection maps, Ovation-Prime precipitation, WACCM-X modeling, and OMNI solar wind data. The main finding is that TEC diurnal maxima correlate much more strongly with plasma convection velocity ($R \approx 0.8783$) than with auroral precipitation ($R \approx 0.3064$), suggesting convection-driven transport dominates TEC enhancements in the south polar region during strong storm main phases. The authors discuss implications for SwMI coupling asymmetries and outline directions for expanding the dataset to improve predictive capabilities for space weather impacts in Antarctica.

Abstract

The present investigation is directed at exploring southern polar ionospheric responses to intense space weather events and their correlations with plasma convection and auroral precipitation. The main phases of six geomagnetic storms occurring in the year 2023 (ascending phase of the present solar cycle) are considered for this study. The ionospheric Total Electron Content (TEC) measurements derived from GPS receivers covering the Antarctic region are used for probing the electron density perturbations during these events. Auroral precipitation maps are shown to illustrate the locations of the GPS stations relative to particle precipitation. SuperDARN maps are shown to understand the effects of plasma convection over these locations. Correlation between the enhanced TEC observations with the auroral precipitation (R $\sim$ 0.31) and the plasma convection (R $\sim$ 0.88) reveals that the latter is more responsible for causing significant enhancements in the diurnal maximum values of TEC over the Antarctic region in comparison to the former. Therefore, this work shows correlation studies between two physical processes and ionospheric density enhancements over the under-explored south polar region under strong levels of geomagnetic activity during 2023.

Figures (5)

• Figure 1: From Top to bottom: variations in the IMF (nT) $B_z$ (red) and $B_y$ (blue), the $V_{sw}$ (km/s), the density (n/cc), the $IEF_y$ (mV/m) along with the westward auroral electrojet SML and the SYM-H variations (nT) during March 23-25, 2023. The peach-shaded region shows the main phase of this storm.
• Figure 2: Diurnal TEC variations (top panel: GPS-derived observations and bottom panel: WACCM-X simulations) over the four Antarctic stations: palm, mtri, bhrt, and sctb during March 23-25, 2023.
• Figure 3: Auroral precipitation pattern over the south polar region on March 23, 2023, at 13 UT. The four stations are marked on the map to observe their locations with respect to the auroral oval and particle precipitation.
• Figure 4: Two-cell convection pattern over the south polar region on March 23, 2023, during the 13:00-13:02 UT window. The four stations are marked on the map so that their locations can be observed with respect to the convection pattern. The dawn (red) cell shows positive potential (+ sign), while the dusk (blue) cell shows negative potential (X sign).
• Figure 5: Correlation between the plasma convection (top) and the particle precipitation (bottom) with the diurnal maximum of TEC. The six geomagnetic storm (GS1 to GS6) events are designated following the nomenclature adapted in Table \ref{['tab1']}.