Nighttime enhancements in TEC near the crest of no

Authors: A Jain S Tiwari S Jain A K Gwal

Publish Date: 2011/10/25

Volume: 85, Issue: 9, Pages: 1367-

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Abstract

Enhancement in nighttime total electron content TEC near the crest of equatorial ionization anomaly at Bhopal Geog 232°N 774°E and MLAT 142°N has been studied for the solar minimum period March 2005 November 2006 TEC data recorded by GPS Ionospheric Scintillation and TEC Monitor GISTM GSV4004A receiver is used for the study and results are presented in the paper More than 10 increase in TEC with respect to background content is considered for analysis Out of total 138 enhancements 65 observed during pre midnight hours and 73 during post midnight hours It is observed that nighttime enhancement in TEC at Bhopal occurs in all seasons it is more frequent during summer less during equinox and least during winter months The enhancement in nighttime TEC can be observed both in geomagnetic disturbed time and in quiet time We found that mean peak amplitude for premidnight TEC enhancement are more in equinox and less in winter while in postmidnight TEC enhancement it is highest in summer and less in winter Postmidnight enhancements have smaller peak amplitude as compared to premidnight Also the most probable values for pre and postmidnights are 44 TECU and 217 TECU respectively The percentage occurrence of nighttime TEC enhancement does not show any dependence on solar activity whereas the peak amplitude depends on solar activity The percentage occurrence of nighttime TEC enhancement decreases as the magnetic activity increases whereas there is no such dependency found with peak amplitude It is also observed that majority of nighttime TEC enhancements are occurred without scintillation The localised nighttime TEC enhancements near the crest of equatorial ionization anomaly region have been observed most of the nights during the period of study

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