Cross-Scale Quantification of Storm-Time Dayside Magnetospheric Magnetic Flux Content: A Statistical Analysis

Interplanetary coronal mass ejections (ICMEs) are massive releases of solar plasma capable of disrupting the interplanetary magnetic field (IMF), leading to geomagnetic storms on Earth. Understanding the processes by which ICMEs interact with Earths magnetosphere would enhance our ability to predict and mitigate damage caused by these periods of heightened solar wind. Using in situ measurements from the heliophsyics system observatory (HSO), including data from OMNI, MMS, GOES, and the Van Allen Probes, we examine 48 large geomagnetic storm events (SYM-H < -50 nT) associated with ICME events over a period of four years (08/2015-10/2018). Magnetic flux content of Earths dayside magnetosphere during different storm phases are investigated, leading to the discovery of flux erosion during storm main phase. The flux erosion is due to different reconnection rates at the dayside and in the magnetotail, resulting in the flux transported to the magnetotail to be greater than the rate at which flux is recovered in the dayside magnetosphere. Superposed epoch analysis of the storm events indicates that the magnitude and the rate of flux erosion during storm main phase are directly proportional to the difference in dayside and magnetotail reconnection rates.