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IJRSP Vol.40 [2011] >
IJRSP Vol.40(1) [February 2011] >
| Title: | Diurnal and seasonal variation of GPS-TEC during a low solar activity period as observed at a low latitude station Agra |
| Authors: | Chauhan, Vishal
Singh, O P
Singh, Birbal |
| Keywords: | Ionospheric total electron content (TEC)
GPS-TEC variation
Solar activity
Global ionospheric maps (GIMs) of TEC |
| Issue Date: | Feb-2011 |
| Publisher: | NISCAIR-CSIR, India |
| PACS No.: | 94.20.dv; 96.60.qd |
| Abstract: | Employing a dual frequency GPS receiver at a low latitude station Agra (geographic
lat 27.120N, long 78.890E, dip 41.10), India
(located just outside the equatorial anomaly crest), the measurement of
ionospheric total electron content (TEC) has been carried out since 24 June
2006. Three years of data for a low solar activity period during 01 August 2006
- 31 July 2009 has been analysed. The temporal, seasonal and solar activity
dependence of GPS-TEC data has been studied for the ionospheric region around
Agra. The results show that the mean TEC varies from a minimum at 0500 hrs LT
(LT=UT+5.5 hrs) to a peak value at about 1400 hrs LT and then decreases. The
lowest values of TEC have been observed in winter whereas highest values have
been observed in equinox and summer. The variation of the data has been
compared with the variation of three solar indices, i.e. EUV flux, 10.7 cm
solar radio flux (F10.7), and sunspot numbers (SSN) during the
period of analysis. It is found that all the solar indices show high
correlation with day maximum TEC (TECmax) in the summer than in
equinox and low correlation is shown in winter season. It is also found that
the data show high correlation with F10.7 in the two seasons of
summer and equinox while the same is found with EUV flux in winter. The
correlation of TECmax and SSN is found to be low as compared to
those of F10.7 and EUV flux in all seasons. The GPS-TEC data
obtained at Agra station for the year 2009 has also been compared with global
ionospheric maps (GIMs) of TEC and a very good correlation is found between the
two. Further, GIMs of TEC have been analysed for five different latitudes along
the common meridian of 800E longitude. The present study has been
carried out for three months of the year 2009 in each season. The role of
equatorial ionization anomaly (EIA) crest is clearly visible on TEC data. These
results are significant for Agra station which is a new location in the low
latitude sector of Indian region. |
| Page(s): | 26-36 |
| CC License: |  CC Attribution-Noncommercial-No Derivative Works 2.5 India |
| ISSN: | 0975-105X (Online); 0367-8393 (Print) |
| Source: | IJRSP Vol.40(1) [February 2011]
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