TEC storm on November 6, 2001, derived from dense GPS receiver network and ionosonde chain over Japan

Ionospheric disturbances during a magnetic storm on November 6, 2001 were analyzed using total electron content (TEC) calculated from measurements made with a dense GPS receiver network, GEONET, which covers the whole of Japan and F-layer peak parameters obtained by a meridional ionosonde chain. Maps of TEC as a function of latitude and time were compared with NmF2 and hpF2. A weak to moderate ionospheric positive storm in terms of foF2 was associated with the magnetic storm. On the other hand, TEC was nearly doubled at all latitudes during the daytime. The significant difference in storm signatures between NmF2 and TEC was interpreted as increased upward plasma diffusion, which worked as a sink for the plasma at the F layer peak. The increase in TEC in the plasmasphere, however, was the order of 10 TEC units, which is insufficient to cause the large observed TEC enhancement but was responsible for maintaining the nighttime TEC enhancement. On the bottom side, the plasma-distribution departed significantly from the photo-chemical equilibrium due to the upwelling, and the photo-chemical production tended to adjust it, providing the major source of the great increase in TEC.