Longitudinal inequalities in Sq current system along 20 deg - 210 deg E meridian

Abstract

In the present study, longitudinal inequalities in Sq current system have been examined utilizing the data of northern and southern hemispheric stations for the period 1976 - 1977 along 200-2100 E meridian. The anomalous behavior in the horizontal component (H) at a few southern hemispheric stations reveal that the solar quiet daily (Sq) variations in longitudinal sector (20o-120o E) do not show the expected V type or inverted V shaped variations but instead are marked by northern hemispheric D variations. The technique of Principal Component Analysis (PCA) is applied to the D, H and Z components of the Earth’s magnetic field. First Principal Component (PC-1) brings out a well defined anticlockwise loop with focus near geomagnetic latitude (~ 26.0o N) at 11 hours local time in the northern hemisphere and clockwise with focus near geomagnetic latitude (~ 43.2o S) at 12 hours local time in the southern hemisphere. This phenomenon has been observed during summer months and disappearance of the northern and southern hemispheric ‘Sq-Vortex’ during winter months. Anomalous deformation of Sq vortex, confined to longitudinal sector (20o to 120o E) may arise due to the changes in the local ionospheric conductivity and tidal winds driven by the main geomagnetic field.