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)