Statistical study of relationship between medium-scale traveling ionospheric disturbance and sporadic E layer activities in summer night over Japan

We investigate the relationship between medium-scale traveling ionospheric disturbance (MSTID) and sporadic E (Es) layer activities in summer nights by analyzing total electron content (TEC) data obtained from a global positioning system (GPS) network in Japan and ionosonde data obtained at Kokubunji, Japan during May-August in 2001-2005. MSTID activity is defined as δI/I¯, where δI is standard deviation of the TEC perturbations over Kokubunji within 1 h, and I¯ is the background TEC. By analyzing nighttime-averaged (19-02 LT) values of MSTID activity and Es layer parameters, we find that the MSTID activity is closely correlated with f0Es and f0Es-fbEs. This result suggests that MSTID and the spatial structures of Es layer could be generated by an electro-dynamical coupling process between the Es layer and F region through polarization electric fields. Furthermore, we suggest that the appearance of the Es layer in the summer hemisphere could play an important role in generating MSTIDs in both hemispheres.