The Johns Hopkins University/Applied Physics Laboratory HF radar at Goose Bay often sees F-region drifts or electric fields which are associated with field line resonances in the Earth's magnetosphere. These resonances are seen in the interval from local midnight to morning, and have discrete, latitude-dependent frequencies at approximately 1.3, 1.9, 2.6-2.7, and 3.2-3.4 mHz. We show that these frequencies are compatible with MHD waveguide modes, with antisunward propagation and reflection at the magnetopause and at turning points on dipolar field lines. ¿ American Geophysical Union 1992