Localized enhancements of total electron content in Southern Hemisphere

Localized enhancements of total electron content (TEC) are usually registered during magnetic storms and are often believed to be connected with storm enhanced density (SED) events. Investigating global ionospheric maps we found that such localized TEC enhancements (LTE) could be observed in Southern Hemisphere during both disturbed and quiet time with no clear dependence on parameters of near space. Analysis of occurrence of LTEs in the regions of Indian and Southern Atlantic Oceans showed that part of them (observed during magnetic storms and localized in subpolar latitudes) can be connected with SEDs. Since another part of subpolar LTEs is detected during relatively quiet conditions its generation mechanism should be different despite they have similar spatial distribution. Most of the enhancements are observed in middle latitudes and is detected during all the investigated years. The occurrence rate of LTEs hardly depends on solar activity and the most probable season for LTE detection is April-September (autumn-winter).

Here we investigate reasons of generation both midlatitudinal and subpolar LTEs trying to define the mechanisms of their generation in details.