Variations of ionospheric TEC at geomagnetic conjugate points during solar minimum

Abstract

We have studied the variations of TEC at quasi-conjugate points using data obtained from GPS receiver at Syowa station, Antarctica (SYOG) (GC: −69.00° S, 39.58° E; CGM: −66.08°S, 71.65 E°), and Árholt station (ARHO), Iceland (high Arctic region) (GC: 66.19° N, 342.89° E; CGM: 66.37°S, 71.48 E°) for a period in 2007, during the minimum phase of solar cycle 23. The GPS measurements of IGS and IMO network were used to create TEC maps. The time resolution of TEC maps is about 1 hour. The TEC maps show that the maximum TEC value over SYOG is at 1000 UT (1300 LT) while in ARHO is at 1300 UT (UT = LT). March 2007, when it was summer in the southern polar region, the TEC value over SYOG range was higher by 3 TECU than ARHO, which was experiencing winter during that time. This has proved the role of sun in the TEC distribution with photoionization process. The measurements of the TEC variation obtained from GPS during different months at both hemispheres showed symmetry in the median TEC at the conjugate points.