Plasmaspheric electron content in the GPS ray paths over Japan under magnetically quiet conditions at high solar activity

Abstract

Vertical total electron content (GPS-TEC) data obtained from the dual-frequency GPS receiver network (GEONET) in Japan are compared with those calculated using the Sheffield University plasmasphere-ionosphere model (SUPIM). The model is also used to estimate the electron content in the plasmaspheric sections of GPS ray paths for the three seasons of high solar activity (F10.7 = 165) under magnetically quiet conditions. According to the estimates, the plasmaspheric sections of vertical GPS ray paths over Japan at altitudes above the O + to H + transition height and above the upper altitude (2500 km) of Faraday rotation contain up to 11 and 9 TEC units (1 TEC unit = 10 16 electrons m −2 ) of free electrons, respectively. The free electrons present above the Faraday rotation altitude can cause propagation errors of up to 4.9 ns in time delay and 1.6 m in range at the GPS L1 (1.57542 GHz) frequency. The plasmaspheric electron content, PEC, changes appreciably with season and latitude and very little with the time of the day. However, the percentage contribution of PEC to GPS-TEC changes most significantly with the time of the day; the contribution varies from a minimum of about 12% during daytime at equinox to a maximum of about 60% at night in winter.

Similarity and differences in morphology and mechanisms of the <i>fo</i>F2 and TEC disturbances during the geomagnetic storms on 26–30 September 2011

“…This effect is even more pronounced during nighttime at the solar activity minimum, where the plasmaspheric contribution to TEC can exceed the ionospheric one (Lunt et al, 1999a, b;Cherniak et al, 2012;Klimenko et al, 2015c). In fact, the TEC variability depends on the lower and topside ionosphere as well as the plasmasphere (Balan et al, 2002;Gulyaeva and Gallagher, 2007;Yizengaw et al, 2008;Cherniak et al, 2012;Lee et al, 2013;Zakharenkova et al, 2013;Klimenko et al, 2015b, c;Lei et al, 2015). Previous studies have demonstrated both the positive correlation between TEC and foF2 at high and middle latitudes during many storm events and no evident correlation between TEC and foF2 at low and middle latitudes during some storms (Maruyama et al, 2004;Liu et al, 2012).…”

Vertical electron density and topside effective scale height (<I>H</I><sub>T</sub>) variations over the Indian equatorial and low latitude stations

“…This reveals that the shape of the IRI derived vertical electron density profile is contributing a major input to the deviations in TEC. It should be mentioned here that the TEC values from both reconstructed profiles and IRI-2007 profiles are expected to be lower than that of GPS-TEC, as the integration is done from the bottom side to only up to 1000 km altitude, whereas, the GPS-TEC also accounts for the plasmaspheric content up to GPS altitudes (∼22 000 km) (Balan et al, 2002). However, the observed differences between the GPS-TEC and the TEC derived from IRI-2007 profiles are quite larger and in a few cases TEC from reconstructed profile is larger than that of the GPS-TEC.…”

A new technique for mapping of total electron content using GPS network in Japan

“…Electron contents above 1,000 km altitude are extrapolated to match the results reported by Balan et al (2002). Solar maximum equinox −2.0 ± 0.1 TECU −2.5 ± 1.4 TECU −1.9 ± 2.7 TECU Solar maximum winter −0.4 ± 0.9 TECU 0.0 ± 1.6 TECU 2.0 ± 2.9 TECU Solar maximum summer −2.8 ± 0.6 TECU −2.8 ± 0.9 TECU −2.9 ± 1.7 TECU Solar minimum equinox −0.6 ± 0.5 TECU −1.5 ± 1.3 TECU −2.6 ± 2.3 TECU Solar minimum winter −0.6 ± 0.5 TECU −0.9 ± 0.8 TECU −0.8 ± 1.3 TECU Solar minimum summer −0.6 ± 0.3 TECU −1.2 ± 0.6 TECU −2.3 ± 1.5 TECU Averages and standard deviations of difference between the estimated vertical TEC and the corresponding vertical TEC given by the model based on the IRI-95 model over three locations for three seasons under solar maximum and minimum conditions.…”

“…According to Lunt et al (1999b), the plasmaspheric electron content in the European sector is 2 TECU at the solar minimum while the corresponding value in the American sector is about 0.5 TECU. Balan et al (2002) have obtained the plasmaspheric electron contents over Japan by comparing TEC obtained from the GEONET with that derived from SUPIM for different seasons at high solar activity. According to their study, the plasmaspheric contribution to the GPS TEC is up to 12 TECU at high solar activity, which changes appreciably with season and latitude and very little with the time of day.…”