TO ACCURATELY MODEL AND FORECAST THE EARTH S RADIATION BELT AND ENERGETIC PLASMA ENVIRONMENT REQUIRES A ROBUST SPECIFICATION OF THE PHYSICAL PROCESSES CONTROLLING THE DYNAMICS WITHIN THE ENVIRONMENT. ONE OF THE KEY PROCESSES IN RADIATION BELT DYNAMICS IS RADIAL DIFFUSION VIA ULTRA-LOW FREQUENCY WAVES WHICH CAN DRIVE ENERGETIC ELECTRON ACCELERATION TRANSPORT AND LOSS IN THE REGION OF THE EARTH S RADIATION BELT. IN THIS PROPOSAL WE WILL DEVELOP A STATE-OF-THE-ART ULF RADIAL DIFFUSION MODEL USING AN AUTO REGRESSIVE INTEGRATE MOVING AVERAGE MODEL WITH EXOGENOUS VARIABLES (ARIMAX) TO SPECIFY ULF WAVE POWER AND RADIAL DIFFUSION COEFFICIENTS. THIS NEWLY DEVELOPED MODEL WILL BE TESTED BY COMPARING MODEL OUTPUT WITH OBSERVATIONS OF ULF WAVE POWER FROM GROUND-BASED MAGNETOMETER AND OUTER RADIATION BELT ELECTRONS FROM THE VAN ALLEN PROBES DURING SELECT GEOMAGNETIC STORMS. METRICS AND SKILL SCORES WILL BE USED TO TEST THE ROBUSTNESS OF THE NEW MODEL AND COMPARE WITH HISTORICAL MODELS OF ULF WAVE RADIAL DIFFUSION COEFFICIENTS. THE TWO MAIN OBJECTIVES OF THIS STUDY ARE: 1. DEVELOP A STATE-OF-THE-ART ARIMAX MODEL OF ULF WAVE POWER AND THE RESULTING RADIAL DIFFUSION COEFFICIENTS FOR USE IN RADIATION BELT SIMULATIONS AND FORECASTS. 2. VALIDATE THE ARIMAX MODEL AND RADIATION BELT SIMULATIONS AND FORECASTS USING THE NEWLY DERIVED RADIAL DIFFUSION COEFFICIENTS. THESE OBJECTIVES WILL BE ACCOMPLISHED USING GROUND-BASED MAGNETOMETERS AND SOLAR WIND OBSERVATIONS TO DEVELOP AN ARIMAX MODEL OF ULF WAVE POWER AND SUBSEQUENTLY CALCULATE ULF WAVE RADIAL DIFFUSION COEFFICIENTS. THESE NEW MODELS WILL BE TESTED AND ACCEPTED VALIDATION METRICS WILL BE USED TO QUANTIFY THE SKILL OF THE MODELS. THE OBJECTIVES OF THIS STUDY ARE SIGNIFICANT TO THE SPACE WEATHER OPERATIONS TO RESEARCH GOALS IN THAT IT DIRECTLY ADDRESSES THE NASA AND NOAA FOCUS AREA TO ADVANCE FORECAST MODELS OF ENERGETIC PARTICLES IN THE EARTH S MAGNETOSPHERE. SPECIFICALLY THE WORK PROPOSED HERE WILL DEVELOP STATE-OF-THE-ART INPUTS USED IN RADIATION BELT MODELLING ENABLING IMPROVED FORECASTS OF THE ENERGETIC PARTICLE ENVIRONMENT ENCOUNTERED BY SPACECRAFT WITHIN EARTH S MAGNETOSPHERE.