Spatial variability of total electron content in the eastern Mediterranean region


  • Haim Soicher,

  • John A. Klobuchar,

  • Patricia H. Doherty


Faraday rotation observations were conducted at Haifa, Israel (32.87°N, 35.09°E), and Athens, Greece (37.97°N, 23.72°E), during the maximum phase of the current solar cycle using the VHF beacon of the SIRIO satellite. The subionospheric points (at 420 km) are (29.9°N, 27.9°E) and (34.5°N, 18.4°E), and the subionospheric L shell values are 1.24 and 1.37, respectively. Expected latitudinal and local time differences in total electron content (TEC) for the two locales are observed. However, the Haifa data are characterized by generally occurring, seasonally independent, large postsunset electron content maxima which are absent for the Athens data. Furthermore, the postsunset increases would appear to be a solar maximum phenomenon, as they are not observed during the minimum phase of the solar cycle. The postsunset increases are attributed to electron fluxes arriving from the equatorial regions along the magnetic lines of force. The correlation coefficients of hourly TEC at the Haifa/Athens locales exhibit a seasonally independent diurnal variation with minimum values at night and maximum values generally at the end of the buildup phase of TEC variation. The daytime ratios of the standard deviation of TEC to the average TEC are generally seasonally independent and behave quite similarly at the two locales, with daytime values below ∼25%.