Analysis of the global ionospheric disturbances of the March 2015 great storm

TLDR: In this article, the global ionospheric storm in March 2015 was investigated using data from over 3000 GPS stations worldwide, and the results show that, based on the multiple methods above, we all observed that, for the first time, there were three equatorward traveling ionosphere disturbances (TIDs) in the main phase of this storm.

Abstract: The global ionospheric storm in March, 2015 was investigated using data from over 3000 GPS stations worldwide. In this study, Total Electron Content(TEC), Rate of TEC(ROT) and ROT's standard deviation ROTI, as well as the second-order difference operator TECT, were considered as main characteristic methods to distinguish ionosphereic disturbances.The results show that, (1) Based on the multiple methods above, we all observed that, for the first time, there were three equatorward traveling ionospheric disturbances (TIDs) in the main phase of this storm. In North America, the disturbance zone expanded to ~40°N; the disturbance periods and AE peak stages were roughly synchronous. We suggest that these three TIDs were induced by the propagation of AGWs to low latitudes under the action of AE. (2) The most intense positive storm occurred over South America and the South Atlantic (over 300% enhancement; 00:00–05:00 UT March 18), whereas a negative storm was observed in the corresponding region of the NH. Such inverse hemispheric asymmetry in intensity and structure can be explained by the variations of the thermospheric composition, the IMF By component and the geomagnetic intensity. (3) On March 18, a negative storm dominated globally (except at certain low latitudes), and tended to propagate equatorward and decay with time, which could be largely attributed to the storm circulation theory. And the evolution of the negative storm was further characterized by the foF2 variations of ionosondes.