DAYSIDE IONOSPHERIC CONVECTION CHANGES IN RESPONSE TO LONG-PERIOD INTERPLANETARY MAGNETIC-FIELD OSCILLATIONS - DETERMINATION OF THE IONOSPHERIC PHASE-VELOCITY - SAUNDERS, MA; FREEMAN, MP; SOUTHWOOD, DJ; COWLEY, SWH; LOCKWOOD, M; SAMSON, JC; FARRUGIA, CJ; HUGHES, TJ (JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 1992)