Variations of the magnetic flux content in the innermagnetosphere during an intense storm

During the intense storm of December 19, 2015, we benefited from an exceptional configuration of several space missions (MMS, THEMIS, GOES, RBSP) in the inner magnetosphere from the dayside magnetopause to 13 Earth’s radii in the geomagnetic tail . The observations are satisfactory fitted by the simple Tsyganenko model T96. We use it to compute the pattern of closed drift shells of equatorial energetic particles. This pattern shows a strong compression during the Storm Sudden Commencement (SSC) and an increase of total magnetic flux content of about 120 MWb relative to the quiet phase before the storm. Conversely, during the main phase and the first recovery day, we find a decrease by about -800 MWb which could be caused by the effect of cross-tail currents in the plasma sheet on the nightside. These orders of magnitude demonstrate that inner magnetosphere plays an important role in the magnetic flux transport in response to solar wind events.