Ma and Maruyama, based on GPS TEC data and Kokubunji ionosonde foF2 data, reported that seasonal variations of ionospheric slab thickness during a daytime exhibits opposite phase with respect to the nighttime variation. Ionospheric slab thickness depends on three parameters; latitude, season, and solar activity. In the summer, ionospheric slab thickness is greater during daytime than in the night. The ionospheric slab thickness depends linearly on the solar activity. Jayacandran et al. concluded that the diurnal varia tion of the ionospheric slab thickness during low solar activity period is generally characterized by higher value in the night than during the day, while the situation is reversed during high solar activity at the non auroral region. In auroral areas, the nighttime slab thickness is higher than the daytime one during both low and high solar activity periods. Variability of ionospheric slab thickness is higher in the night than during the day in the two phases of solar activity for mid, low and high latitude ionosphere. Suvannasang et al. concluded that the diurnal variation of the ionospheric slab thickness reaches its maximum value at 05:00 LT. The average daytime slab thickness is minimized at around equinox, whereas the average nighttime slab thickness is maximized during summer.
Author(s) Details:
Buldan Muslim
Geospatial Research Center of National Research and Innovation Agency (BRIN), Indonesia.
Mukhamad Nur Cahyadi
Sepuluh Nopember Institute of Technology, Surabaya, Indonesia.
Haris Haralambous
Frederick University, Cyprus
Christina Oikonomou
Frederick University, Cyprus
Recent global research developments in Diurnal Variation of Ionospheric Slab Thickness
The Ionospheric Equivalent Slab Thickness:
- The ionospheric equivalent slab thickness (represented as \\tautau) characterizes both the distribution of plasma in the ionosphere and the shape of the corresponding vertical electron density profile.
- It is calculated as the ratio of the vertical total electron content (vTEC) to the ionospheric F2-layer electron density maximum (NmF2).
- Since its definition in the 1960s, research has accumulated information on \\tautau under different helio-geophysical conditions, demonstrating its connection with various plasma properties.
- The advent of the Global Positioning System (GPS) era in the 1990s significantly impacted studies on \\tautau due to GPS signals providing vTEC data up to about 20,000 km altitude.
- Recent applications of \\tautau include data assimilation methodologies for improving empirical ionospheric models based on near real-time data[1].
Statistical Studies:
- Researchers have conducted comprehensive statistical analyses of \\tautau at various locations:
- Beijing: A study analyzed TEC and NmF2 data from 2010 to 2017, revealing different diurnal variations at different seasons during high/low-solar-activity years[2].
- Guam (near the magnetic equator): Another study investigated diurnal, seasonal, solar, and magnetic activity variations in \\tautau using GPS-TEC and ionosonde NmF2 data from 2012 to 2017.
- Global Picture: A global analysis of \\tautau based on Global Ionospheric Map (GIM) TEC data highlighted its diurnal and temporal variations during a solar minimum year (2007).
References
- Pignalberi, A., Pietrella, M., Pezzopane, M. et al. The Ionospheric Equivalent Slab Thickness: A Review Supported by a Global Climatological Study Over Two Solar Cycles. Space Sci Rev 218, 37 (2022). https://doi.org/10.1007/s11214-022-00909-z
- Zhang, Y., Zhou, Y., Zhang, F., Feng, J., Xu, T., Deng, Z., … & Zhou, C. (2023). Statistical Study of the Ionospheric Slab Thickness at Beijing Midlatitude Station. Remote Sensing, 15(9), 2229.
