Solar cycle influences on the shape and location of the Earth's magnetopause

We have developed an automated routine to determine the location of the Earth's magnetopause using a combination of in situ plasma and magnetic field data. The technique has been applied to almost two solar cycles of Geotail spacecraft data (1996 - 2015), producing a database of 8561 magnetopause crossings. The magnetopause crossings are normalised for solar wind dynamic pressure, and the shape of the magnetopause is modelled with the functional form of the Shue et al. (1997) empirical model for each of the 20 years of data. We find that the yearly averaged level of flaring in the magnetotail and magnetopause standoff distance vary significantly throughout the solar cycle, and that our improved coverage of the flanks is essential for accurately characterising the flaring of the nightside magnetopause. We also find that the shape of the magnetopause depends on the ring current strength and the amount of open magnetic flux in the system.