SCIENCE GOALS AND OBJECTIVES: WE PROPOSE A SYSTEMATIC INVESTIGATION OF THE ROLE OF DISTURBANCE ELECTRIC FIELDS OF MAGNETOSPHERIC ORIGIN ON THE IONOSPHERIC ELECTRON DENSITY DYNAMICS REDISTRIBUTION AND OCCURRENCE OF SPREAD-F TYPE INSTABILITIES. THESE TRANSIENT LATITUDE MLT AND LONGITUDE-DEPENDENT ELECTRIC FIELDS ARE KNOWN TO PRODUCE LARGE CHANGES IN IONOSPHERIC ELECTRON DENSITIES AND AFFECT CONDITIONS FAVORABLE FOR OCCURRENCE OF SPREAD F INSTABILITIES. BOTH RECENT OBSERVATIONS AND THEORY INDICATE THAT TRANSPORT IN THE PLASMA SHEET WHICH CONTROLS FORMATION OF REGION-2 CURRENTS IS A BI-MODAL PROCESS OF FAST AND NARROW CHANNELS OF DEPLETED ENTROPY REGIONS ( BUBBLES ) SPORADICALLY SUPERIMPOSED ON THE BACKGROUND LARGE-SCALE CONVECTION.