A Storm-Time Super Bubble as Observed with Dense GPS Receiver Network at East Asian Longitudes

Abstract

A post sunset plasma bubble manifested by TEC depletion was observed at midlatitudes (ca.30-34 deg N, ca.130-134 deg E) during the main phase of a geomagnetic storm on 12 February 2000. The storm was characterized by southward turning IMF B(sub z) preceded with storm sudden commencement. With loss of lock and ROTI maps, the bubble was seen to bifurcate at the early growth phase of the storm. The upward drift speed was observed ca. 300 m/s at ca. 2150 km, and decreasing with increasing altitude and time. The bubble had unusually large latitudinal extension reaching midlatitude of 36.5 deg N (31.5 deg N magnetic latitude), indicating an apex height of ca. 2550 km at the magnetic equator. In process of the evolution, the bubble drifted eastward at a speed of ca. 50 m/s. The F region peak height and density obtained by a meridional ionosonde chain suggested a prompt penetrating magnetospheric electric field helped to trigger the super bubble.