Total electron content variations due to nonclassical traveling ionospheric disturbances: Theory and Global Positioning System observations

Abstract

Abstract. Measurements of total electron content (TEC) variations are easy to perform. As several authors have pointed out, however, TEC variations must be interpreted carefully since TEC is an integrated quantity. Prior studies of TEC variations have considered these variations to stem from "classical" gravitywave interaction with the ionosphere at midlatitudes; that is, the component of gravity-wave neutral wind perturbations along the local magnetic field moves the charged particles up and down the field lines. Recent evidence suggests that at night, in the absence of photoproduction and when E layer conductivity becomes small, electrodynamic effects come into play and gravity-wave perturbations can yield vertical movement of the F layer, rather than movement along the field lines. Here we consider the TEC variations resulting from horizontally propagating disturbances in ionospheric height.

Two‐dimensional imaging of large‐scale traveling ionospheric disturbances over China based on GPS data

“…Based on the study of Georges and Hooke [1970], TEC perturbations in Figures 3 and 4 can be interpreted as enhancements or depletions of electron density caused by atmospheric gravity waves. Some authors have stated that daytime gravity waves carry the charged particles along the magnetic field lines and cause variations in electron density [ Jacobson et al , 1995; Beach et al , 1997]. However, Beach et al [1997]indicated that nighttime gravity waves can produce vertical motion in the ionosphere, which can be measured by the ray‐path difference in slant TEC.…”

“…Some authors have stated that daytime gravity waves carry the charged particles along the magnetic field lines and cause variations in electron density [ Jacobson et al , 1995; Beach et al , 1997]. However, Beach et al [1997]indicated that nighttime gravity waves can produce vertical motion in the ionosphere, which can be measured by the ray‐path difference in slant TEC. At night, the vertical force balance among diffusion, gravity, and electric fields dominates the ionosphere due to the absence of photoproduction [ Kelley , 1989].…”

A study on chaotic behaviour of equatorial/low latitude ionosphere over Indian subcontinent, using GPS-TEC time series

“…Ho et al (1996) studied the global distribution of TEC variations during magnetically disturbed period with more than 60 worldwide GPS receivers. TEC variations in a local area have also been studied with GPS receivers in equatorial (Kelley et al, 1996), mid-latitude (Beach et al, 1997), and high latitude (Aarons, 1997) regions. Saito et al (2002) have conducted studies on nighttime TIDs propagating through the Japanese mid-latitude sector with velocities up to 150 m/s, which produce magnitude of perturbation structures (with respect to the background content) up to 1 TECU (1 TECU¼10 16 electrons/m 2 ).…”

Monitoring, tracking and forecasting ionospheric perturbations using GNSS techniques

“…The immediate response of TEC at storm onset, as shown in Figure 5 at 06:30 UT, is a typical phenomenon which becomes clearly visible when strong storms with a well-defined onset are superposed (Arbesser-Rastburg & Jakowski 2007). In that case the storm onset was defined by a rapid increase of the geomagnetic D st index (DD st /Dt > 10 nT/hour) before the main storm phase starts with a strong depression of D st .…”