Magnetopause Shape and Location in a Light of New Observations

First magnetopause observations confirmed an expected power-law dependence of its location on the solar wind dynamic pressure but the fact that the power index varies from -1/4.8 to -1/6.6 in different (about equally successful) empirical models suggests that the problem would be treated in a more complex way. An incorporation of the interplanetary magnetic field vertical component (IMF Bz) as a second upstream parameter improved a prediction of magnetopause locations significantly but the uncertainty is still large. Moreover, there are studies showing that the magnetopause can be strongly expanded during intervals when IMF is aligned with the solar wind velocity, during high-speed solar wind streams or when a solar activity is very low. The present contribution analyzes about 30 000 of Geotail, Interball, THEMIS and MMS magnetopause crossings identified in course of a nearly two solar cycles. We analyze the influence of different upstream parameters on the magnetopause shape and location and discuss physical mechanisms leading to magnetopause displacement from its mean position. Since these spacecraft have various orbits, we demonstrate effects of orbital parameters on a development of empirical magnetopause models and suggest a way that can significantly depress these effects.