Study of Ionospheric Irregularities in the Vicinity of SED Region During a Super Geomagnetic Storm

Small-scale ionospheric irregularities can cause strong amplitude and phase scintillations of radio wave signals passing through the ionosphere. In this paper, the phenomena of Storm Enhanced Density (SED) were studied during a super geomagnetic storm in October 2003 by using the TEC data of IGS. Rate of TEC Index (ROTI) is calculated with the observed data of GPS. The ROTI has been used to analyze the spatial and temporal distribution of small scale ionospheric irregularities in the vicinity of SED region. It shows that the irregularities near the SED border were gradually increased with the development of geomagnetic storm during the main phase, and the distribution density reached its maximum value in the latter part of the main phase, and then was reduced during the recovery phase. Initially, the irregularities were mainly distributed in latitudes 40º~45ºN. Subsequently, the irregularities drifted to higher latitude, and were mainly distributed in latitudes 45 º~55ºN. This study provides an important theoretical foundation on revealing the propagation characteristics of radio waves passing through the vicinity of SED region.