Spatio-Temporal Evolution of Global Ionospheric Storm Drivers and Hemispherical Asymmetry During 17–18 March 2015 Geomagnetic Storm

The local, regional, and global morphology of the ionospheric response of the March 2015 geomagnetic storm has been investigated by different studies. However, the spatio-temporal evolution of the drivers of the global ionospheric response to this storm has not yet been investigated, using multi-data sources, in detail. Therefore, in this study drivers of the ionospheric response to the March 17–18, 2015 storm are investigated. Spatial and temporal variations of deposition of solar wind energy are found to be the cause for hemispherical asymmetry of the response of the ionosphere; the American-Canada-Greenland sector, Northern Hemisphere high-latitude ionosphere responded about 12 h earlier than the Southern Hemisphere (SH) high-latitude ionosphere, resulted from hemispherical energy imbalance as detected from Hemispherical Power. The positive ionospheric storm observed in the high-latitude regions is found to be due to solar wind energy deposition at high latitudes. Interestingly, it is found that the Northern hemisphere ionospheric positive storm shifted to the mid-latitude and disappeared there whereas the SH ionospheric positive storm shifted to mid-latitude and then farther to the low-latitude with time; this spatio-temporal evaluation of positive ionospheric storm is found to be due to the spatio-temporal enhancement of the O/N2 ratio. Also, the mid (Europe-African)and low (Brazilian) latitudes positive ionospheric storms prevailed due to prompt penetration electric fields, disturbance dynamo electric fields, and enhancement of the O/N2 ratio. Moreover, the negative ionospheric storm, observed at the NH high and mid-latitudes in the American and Asian sectors, is linked to the reduction of the O/N2 ratio.