SCIENCE GOALS THE EARTH S ELECTRON OUTER RADIATION BELT IS POPULATED BY ELECTRONS INCLUDING ENERGIES OF SEVERAL MEV WHICH ARE USUALLY REFERRED TO AS ULTRARELATIVISTIC ELECTRONS. DURING GEOMAGNETIC STORMS THE ELECTRON FLUXES EXHIBIT IRREGULAR VARIATIONS OVER SEVERAL ORDERS OF MAGNITUDE ON TIME SCALES RANGING FROM MINUTES TO DAYS. THE ANALYSIS OF SUCH DYNAMICS IS COMPLICATED BY THE FACT THAT SOME OF THE VARIATIONS ARE REVERSIBLE OR ADIABATIC AND OTHERS ARE IRREVERSIBLE. WHILE ADIABATIC CHANGES ARE RELATED TO THE SLOW CHANGES OF THE AMBIENT MAGNETIC FIELD IRREVERSIBLE CHANGES ARE THE RESULT OF THE WAVE-PARTICLE INTERACTION AND LOSSES ON THE MAGNETOPAUSE BOUNDARY AND INTO THE ATMOSPHERE. SEPARATING ADIABATIC AND NONADIABATIC CHANGES CAN BE ACHIEVED BY INFERRING PHASE SPACE DENSITY (PSD) AS A FUNCTION OF THREE ADIABATIC INVARIANTS. SIGNIFICANT PROGRESS HAS BEEN ACHIEVED IN UNDERSTANDING THE ELECTRON ACCELERATION MECHANISMS BY ANALYZING THE MONOTONIC PROFILES AND GROWING PEAKS IN PSD. HOWEVER OUR UNDERSTANDING OF LOSSES IS STILL INCOMPLETE. AT HIGH RADIAL DISTANCES THE TOTAL ELECTRON LOSS CAN BE A COMBINATION OF THE LOSS TO THE INTERPLANETARY MEDIUM AND OUTWARD TRANSPORT OF PARTICLES WHEREAS AT LOWER RADIAL DISTANCES IT IS TRADITIONALLY ASSUMED THAT PARTICLES ARE ALL LOST TO THE ATMOSPHERE DUE TO THE PITCH ANGLE SCATTERING. THE RAPID LOCAL LOSSES OF ULTRARELATIVISTIC ELECTRONS ARE POSSIBLY DUE TO WAVE-PARTICLE INTERACTION WITH ELECTROMAGNETIC ION CYCLOTRON (EMIC) WAVES WHICH MAY PLAY A DOMINANT ROLE IN THE OBSERVED DROPOUTS. IN THIS STUDY WE PROPOSE TO ANALYZE PSD PROFILES AND PITCH ANGLE DISTRIBUTIONS BASED ON THE DATA FROM THE VAN ALLEN PROBES GOES AND THEMIS MISSIONS. THE ANALYSIS WILL INCLUDE MULTIPLE DROPOUTS DURING A PERIOD OF OVER 4 YEARS. THE MAIN SCIENTIFIC GOAL IN THIS STUDY IS: THE INVESTIGATION OF THE ROLE OF THE EMIC WAVES AND THE MAGNETOPAUSE IN THE RAPID DROPOUTS OF ULTRARELATIVISTIC ELECTRONS. THE SCIENTIFIC QUESTIONS ARE: 1. UNDER WHICH GEOMAGNETIC CONDITIONS ARE THE DROPOUTS ASSOCIATED WITH AND WITHOUT OBSERVED LOCAL MINIMUM IN PSD? 2. WHERE IN THE RADIATION BELTS (AT WHICH L-SHELL) AND AT WHICH ENERGIES ARE THE CONTRIBUTIONS TO LOSS FROM THE EMIC WAVES SIGNIFICANT AND HOW DOES IT DEPEND ON GEOMAGNETIC CONDITIONS? 3. UNDER WHICH GEOMAGNETIC CONDITIONS DO THE STATISTICAL RADIAL DIFFUSION COEFFICIENTS NOT REPRESENT REALISTIC OUTWARD RADIAL DIFFUSION RATES? DATA THE VAN ALLEN PROBES MAGEIS AND REPT INSTRUMENTS WILL BE USED TO CONSTRUCT THE PSD PROFILES AND PITCH ANGLE DISTRIBUTIONS. THE GOES EPEAD AND MAGED INSTRUMENTS WILL BE USED FOR ACQUIRING MEASUREMENTS AT GEOSYNCHRONOUS ORBIT AND DATA FROM THE THEMIS SST INSTRUMENT OUTSIDE OF GEOSYNCHRONOUS ORBIT. METHODOLOGY WE WILL STUDY ALL ULTRARELATIVISTIC DROPOUT EVENTS DURING THE PERIOD OF VAN ALLEN PROBE MISSIONS OPERATION. TO CALCULATE ADIABATIC INVARIANTS DIFFERENT MAGNETIC FIELD MODELS WILL BE USED AND PSD PROFILES WILL BE CONSTRUCTEDA. LOCAL LOSSES WILL BE IDENTIFIED BY LOCAL MINIMUMS IN PSD AND BY SIMULTANEOUSLY ENSURING THAT THE DIPS WERE NOT A RESULT OF A VARIABLE UPPER BOUNDARY OF THE OUTER RADIATION BELT. TO CONFIRM THE EMIC WAVE ACTIVITY WE WILL SEARCH FOR A NARROWED PITCH ANGLE DISTRIBUTION AS A SIGNATURE OF EMIC WAVE SCATTERING. WE WILL IDENTIFY THE CONTRIBUTION OF THE MAGNETOPAUSE BY IDENTIFYING THE NEGATIVE GRADIENTS IN THE PSD PROFILES TOWARDS THE OUTER BOUNDARY OF THE RADIATION BELTS. WE WILL USE THE VERB CODE SIMULATIONS TO VALIDATE OUR FINDINGS. THE RELEVANCE TO DECADAL SURVEY GOALS THE STUDY IS RELEVANT TO GOALS 2 AND 4 IN THE DECADAL SURVEY: DETERMINING THE ROLE OF EMIC WAVES AND THE MAGNETOPAUSE IN ... THE DYNAMICS AND COUPLING OF EARTH S MAGNETOSPHERE... AND DISCOVER AND CHARACTERIZE FUNDAMENTAL PROCESSES THAT OCCUR BOTH WITHIN THE HELIOSPHERE AND THROUGHOUT THE UNIVERSE AS THE EARTH S MAGNETOSPHERE SERVES AS A COSMIC LABORATORY FOR STUDYING UNIVERSAL PLASMA PHENOMENA