GPS based TEC measurements for a period August 2008– December 2009 near the northern crest of Indian equatorial ionospheric anomaly region

• Published in: Journal of Earth System Science 2011-10, Vol.120 (5), p.851-858
• Main Authors: KARIA, S P, PATHAK, K N
• Format: Article
• Language: English
• Subjects: Annual variations; Atmospheric sciences; data collection; Delay; diurnal variation; Diurnal variations; Earth and Environmental Science; Earth ionosphere; Earth Sciences; earth system science; Earth, ocean, space; Electrons; Equatorial regions; Exact sciences and technology; Geomagnetic activity; geophysics; Global Positioning System (GPS) satellite; Global positioning systems; GPS; Ionosphere; Ionospheric anomalies; Ionospheric electron content; magnetism; monitoring; Navigation; Propagation; Satellite navigation systems; Scintillation; Solar wind; Space Exploration and Astronautics; Space Sciences (including Extraterrestrial Physics; Space weather; summer; Sunspot activity; Sunspots; Total Electron Content; weather; winter
• ISSN: 0253-4126; 2347-4327; 0973-774X
• DOI: 10.1007/s12040-011-0114-1

In recent years, measurements of total electron content (TEC) have gained importance with increasing demand for the GPS-based navigation applications in trans-ionospheric communications. To study the variation in ionospheric TEC, we used the data obtained from GPS Ionospheric Scintillation and TEC monitoring (GISTM) system which is in operation at SVNIT, Surat, India (21.16°N, 72.78°E) located at the northern crest of equatorial anomaly region. The data collected (for the low sunspot activity period from August 2008–December 2009) were used to study the diurnal, monthly, seasonal semi-annual and annual variations of TEC at Surat. It was observed that the diurnal variation at the region reaches its maximum value between 13:00 and 16:00 IST. The monthly average diurnal variations showed that the TEC maximizes during the equinox months followed by the winter months, and are lowest during the summer months. The ionospheric range delay to TEC for the primary GPS signal is 0.162 m per TECU. The diurnal variation in TEC shows a minimum to maximum variation of about 5 to 50 TECU (in current low sunspot activity periods). These TEC values correspond to range delay variations of about 1 to 9 m at Surat. These variations in the range delay will certainly increase in high sunspot activity periods. Detected TEC variations are also closely related to space weather characterizing quantities such as solar wind and geomagnetic activity indices.