Can drift out the magnetopause account for the rapid loss of relativistic electrons from Earth's radiation belt?

The flux of relativistic electrons that populate Earth's outer radiation belt is highly variable and often decreases by orders of magnitude on relatively short timescales of a few hours. One simple explanation for these rapid flux depletions is that electrons are lost to the solar wind when their drift orbits encounter the magnetopause boundary. Whether or not an electron encounters the boundary depends on the magnetic field strength at the boundary and the electron pitch angle. An equatorial electron is expected to drift about Earth following a contour of constant magnetic field strength. Thus, an electron on an L-shell whose field is lower than the field at the magnetopause should encounter the boundary and potentially be lost. Smaller pitch angle particles are expected to be more efficiently lost because their drift paths move farther out on the dayside. To test this theory we analyze several events comparing the magnetic field strength at GOES to that observed at the magnetopause by Geotail. Additionally, we compare the loss of electrons with different pitch angles and find that the observations are not consistent with these expectations.