Analysis of the global spatiotemporal characteristics of ionospheric noontime bite-outs

Abstract This study utilizes global ionospheric map data with high spatiotemporal resolution to analyze the phenomenon of noontime bite-outs in 2014 (a year of high solar activity) and 2020 (a year of low solar activity). By statistically examining the occurrence rate, intensity, and timing characteristics of noontime bite-outs at various grid points, this study explores the impact of solar activity on these phenomena and their spatiotemporal distribution. The results indicate that noontime bite-outs exhibit significant variations with solar activity, season, longitude, and latitude. During years of low solar activity, the occurrence rate of noontime bite-outs is higher and covers a broader area compared to years of high solar activity, while the duration tends to be shorter. The highest occurrence rate is observed in winter, with minimal variation across other seasons. This is primarily because the total electron content (TEC) is lower in the winter hemisphere than in the summer hemisphere, while the duration of noontime bite-outs is longer in summer. The intensity varies by region, with the radio intensity metric being more effective in mid- and high-latitudes, while the absolute intensity metric captures variations more effectively in mid- and low-latitude regions. During noontime bite-outs, the minimum TEC values across all regions typically occur around 13:00 local time. The duration of these patterns ranges from 2.5 to 6 h. The mechanism of noontime bite-outs in high latitude regions differs significantly from that in mid-to-low latitude regions.