Short intervals (<2.5 hrs) of dense (≥10 cm-3), cold (≤10 eV) plasmaspheric plasma are observed at synchronous orbit in association with the growth phase of geomagnetic substorms. We interpret the strong correlation between these phenomena in terms of the reconfiguration of the duskside/nightside magnetosphere during the growth phase of geomagnetic substorms. This reconfiguration moves plasmaspheric plasma outward to synchronous orbit, occasionally even in the midnight region. ¿ American Geophysical Union 1996