Dynamics of Space-Time TEC Enhancements seen in JPL GIMs: Variations with Latitude, Season and Geomagnetic Activity

Total Electron Content (TEC) is central to characterizing ionospheric response to so11 lar and geomagnetic activity. Variations in TEC structures over time provide insight into 12 underlying physical processes and inform monitoring of space weather events, which pose 13 a risk to navigation and communication systems. JPL processed GNSS observations over 14 20 years provide a series of 15-minute Global Ionospheric Maps (GIMs) of spatial res15 olution 1◦×1◦ longitude/latitude. We translate these into geomagnetic coordinates cen16 tered about the sub-solar point and we isolate the top 1% of TEC values in each map 17 to define High Density Regions (HDRs) of TEC. Image processing tools are used to de18 velop an algorithm that detects and tracks these to compile a set of contiguous, uniquely 19 labelled space-time TEC HDRs. We find that HDRs naturally divide into two popula20 tions by peak area, separated by a size of 8.0×106km2, which is around the continen21 tal scale. These populations are studied for different storm conditions - quiet (Kp < 4), 22 moderate (4 ≤ Kp < 7) and extreme (Kp ≥ 7): small HDRs form primarily around 23 four magnetic latitude bands and move roughly parallel to lines of constant magnetic lat24 itude towards later MLT. Large HDRs form around the same latitude bands but follow 25 more complex paths. The statistical nature of these results could be used in predictive 26 ionospheric models and identify reproducible trends on these spatial/temporal scales.