SCIENCE GOALS AND OBJECTIVES: ULF WAVES WITH RADIAL FIELD LINE DISPLACEMENT (POLOIDAL WAVES) WHICH ACCOMPANY AN AZIMUTHAL ELECTRIC FIELD AND A COMPRESSIONAL MAGNETIC FIELD ARE IMPORTANT IN THE PHYSICS OF THE INNER MAGNETOSPHERE (L<6) DURING GEOMAGNETIC STORMS BECAUSE THE WAVES INTERACT WITH ENERGETIC PARTICLES DRIFTING IN THE EARTH S DIPOLAR MAGNETIC FIELD. PREVIOUS STUDIES REPORTED STATISTICAL PROPERTIES OF POLOIDAL ULF WAVES INCLUDING: (1) THE OCCURRENCE PATTERN IN RADIAL DISTANCE AND LOCAL TIME AND (2) THE DEPENDENCE OF THE OCCURRENCE RATE AND AMPLITUDE OF THE WAVES ON SOLAR WIND PARAMETERS AND GEOMAGNETIC ACTIVITY INDICES. THE GOAL OF THE PROPOSED INVESTIGATION IS TO ANALYZE SPACECRAFT DATA TO OBTAIN DETAILED INFORMATION ON POLOIDAL ULF WAVES IN THE INNER MAGNETOSPHERE. IN CONSIDERATION OF DRIFT RESONANCE INTERACTION OF ULF WAVES WITH ENERGETIC ELECTRONS WE WILL FOCUS ON POLOIDAL WAVES WITH SYMMETRIC FIELD LINE DISPLACEMENT ABOUT THE MAGNETIC EQUATOR AND WHEN POSSIBLE WE WILL INFER THE AZIMUTHAL WAVE NUMBER (M). THE SPECIFIC GOALS OF THE PROPOSED INVESTIGATIONS ARE: (1) TO DETERMINE WHETHER A GIVEN WAVE IS DRIVEN BY THE SOLAR WIND DISTURBANCES (SMALL M) OR INTERNAL INSTABILITIES (LARGE M) (2) TO DETERMINE THEIR STATISTICAL PROPERTIES AND (3) TO EVALUATE THE RELATIVE IMPORTANCE OF LOW-M AND HIGH-M WAVES IN TERMS OF THE OVERALL SPECTRAL POWER IN THE INNER MAGNETOSPHERE. OUR PROJECT WILL COVER THE PC4 5 PULSATION BAND (2 22 MHZ). THE MISSION DATA: WE WILL USE FIELDS AND PARTICLE DATA FROM THE RADIATION BELT STORM PROBES (RBSP ALTERNATIVELY KNOWN AS VAN ALLEN PROBES) AND SOLAR WIND DATA FROM THE THEMIS AND OTHER SPACECRAFT. METHODOLOGY. WE WILL DETERMINE THE LOCAL PROPERTIES (FREQUENCY AMPLITUDE POLARIZATION AND FIELD LINE STANDING MODE) OF ULF WAVES USING FIELDS DATA FROM EACH RBSP SPACECRAFT. WE WILL COMBINE DATA FROM THE TWO RBSP SPACECRAFT TO DETERMINE THE SPATIAL EXTENT AND WAVELENGTH OF THE WAVES. PARTICLE DATA FROM RBSP WILL BE EXAMINED FOR SIGNATURES OF DRIFT RESONANCE FOR FINITE LARMOR RADIUS SOUNDING AND FOR INFORMATION ON THE FREE ENERGY TO EXCITE ULF WAVES. SOLAR WIND DATA WILL BE COMPARED WITH THE ULF WAVES TO DETERMINE DIRECT WAVE DRIVING BY SOLAR WIND DISTURBANCES. WE WILL RUN GLOBAL MHD SIMULATIONS TO OBTAIN THE SPATIAL DISTRIBUTION OF THE ENERGY OF LOW-M ULF WAVES DRIVEN BY SOLAR WIND DYNAMIC PRESSURE VARIATIONS. RELEVANCE: SCIENCE QUESTIONS ADDRESSED BY THE RBSP MISSION INCLUDE THE FOLLOWING: 1. WHICH PHYSICAL PROCESSES PRODUCE RADIATION BELT ENHANCEMENTS? 2. HOW DO RING CURRENT AND OTHER GEOMAGNETIC PROCESSES AFFECT RADIATION BELT BEHAVIOR? POLOIDAL ULF WAVES EXCHANGE ENERGY WITH ENERGETIC ELECTRONS THROUGH DRIFT RESONANCE THUS ARE RELEVANT TO QUESTION 1. RING CURRENT IONS EXCITE ULF WAVES. THIS PROCESS MAY REDUCE RING CURRENT ENERGY AND THE EXCITED ULF WAVES MAY INTERACT WITH ENERGETIC ELECTRONS LEADING TO ACCELERATION OR PRECIPITATION LOSS OF THE LATTER. THEREFORE ULF WAVES EXCITED IN THE RING CURRENT ARE RELEVANT TO QUESTION 2.