Statistical Characteristics of Total Electron Content Intensifications on Global Ionospheric Maps

Abstract

Global ionospheric total electron content (TEC) maps exhibit TEC intensifications and depletions of various sizes and shapes. Characterizing key features on TEC maps and understanding their dynamic coupling with external drivers can significantly benefit space weather forecasting. However, comprehensive analysis of ionospheric structuring over decades of TEC maps is currently lacking due to large data volume. We develop feature extraction software based on image processing techniques to extract TEC intensification regions, that is, contiguous regions with sufficiently elevated TEC values than surrounding areas, from global TEC maps. Applying the software to the Jet Propulsion Laboratory Global Ionospheric Map data, we generate a TEC intensification data set for years 2003–2022 and carry out a statistical study on the number and strength of TEC intensifications. We find that the majority of the TEC maps (about 86%) are characterized with one or two intensification(s), while the rest of the TEC maps have three or more intensifications. Both the number and strength of TEC intensifications exhibit semi‐annual variation that peaks near equinoxes and dips near solstices, as well as an annual asymmetry with larger values around December solstice compared to June solstice. The number and strength of intensifications increase with enhanced solar extreme‐violet irradiance. The strength of intensifications also increases with elevated geomagnetic activity, but the number of intensifications does not. In addition, the number of intensifications is not correlated with the strength of intensifications.

Temporal Variability of Equatorial Ionization Anomaly Crest Locations Extracted From Global Ionospheric Maps

“…The intensification characteristics include the maximum, median, and minimum TEC within an intensification region, the geographic longitude and latitude of the TEC maximum, regional electron content as an indication of the intensification strength, intensification size, and the number of GNSS receivers located within and nearby the intensification region. For a more complete description of the data set and how it was generated, we refer the readers to Meng et al (2024).…”

“…The workflow of the feature extraction procedure contains several major steps including computing Laplacian values, applying dilation and erosion, merging and removing objects (Figure S2 in Supporting Information S1). The development, implementation, and application of the feature extraction software are described in detail in Verkhoglyadova et al (2021); Verkhoglyadova et al (2022); Meng et al (2024). Applying the feature extraction software to each JPLD global TEC map during 2003-2022, we have obtained the TEC intensification data set, which records the number of intensifications per TEC map and several characteristics of each intensification (Meng & Verkhoglyadova, 2023).…”