On the Disintegration of the Vortex Structure of Ionospheric Current System along Asian Longitude Sector.

The disintegration of vortex type of ionospheric Sq current system in the northern hemisphere along the Asian longitudes during the local winter months (December solstices) is manifested by the abnormally low daily variation of the eastward component of the geomagnetic field (Y) at any of the stations. Such a weakening of the Sq(Y) field during local winter months is not observed at east African or Australian stations.