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Abstract

This paper represents the comparative studies on of TEC bite-outs of plasma structures on transionospheric radio signals received from Kolkata(Latitude:22.58°N,Longitude:88.38°E geographic;36.2°N mag.dip), a station is situated near the northern crest of the EIA in the Indian longitude sector, using GPS during the equinoxes of 2011-2012 of Solar Cycle 24 and 2021-2022 of Solar Cycle 25. It is observed that when a plasma structures moves across a satellite link, scintillations and ionization are usually encountered. The apparent duration of the TEC bite-outs may be different from the true east-west duration because of the presence of a relative velocity between the irregularity cloud and the satellite. The distributions of amplitude and the parameters characterizing the TEC bite-outs, the duration, depth and the leading and trailing edge slopes of the irregularities structures have been studied during the same periods. It is evident that the range error, extent of the bubble and ionization gradients measured in these equinoctial months of the equatorial region provides the worst case figures for system designers. The high range error(~3-4m) is observed during these equinoctial months. The maximum amplitude of about 23.25 TECU with a median of about 5.92 TECU has been observed during the vernal equinox of 2011.The majority of the bubbles were found to have observed duration between 10-20minutes with a maximum of 28.14minutes with a median value of actual duration of 2.37minutes translates to ~ 150sec of possible signal outage. Similar significant statistical distribution has been investigated during the other equinoctial months of 2011-2012 and 2021-2022.