RELATIVISTIC ELECTRON FLUX IN THE EARTH'S RADIATION BELT ARE OBSERVED TO DROP BY ORDERS OF MAGNITUDE ON TIMESCALES OF A FEW HOURS. WHERE DO THE ELECTRONS GO? THIS IS ONE OF THE MOST COMPELLING OUTSTANDING QUESTIONS IN RADIATION BELT STUDIES. RADIATION BELT ELECTRONS CAN BE LOST EITHER BY TRANSPORT ACROSS THE MAGNETOPAUSE INTO INTERPLANETARY SPACE OR BY PRECIPITATION INTO THE ATMOSPHERE. TRADITIONAL MECHANISMS SUCH AS MAGNETOPAUSE SHADOWING AND WAVE-PARTICLE INTERACTION INDUCED OUTWARD RADIAL DIFFUSION AND PITCH ANGLE DIFFUSION HAVE BEEN INCLUDED TO MODEL THE FAST LOSS OF RADIATION BELT ELECTRONS. HOWEVER IN MANY CASES THE OBSERVED FAST DROPOUTS ARE STILL NOT WELL EXPLAINED CALLING FOR THE IMPLEMENTATION OF NEW PHYSICAL PROCESSES. RECENTLY A MECHANISM CALLED DRIFT ORBIT BIFURCATION (DOB) HAS BEEN SUGGESTED TO PLAY A MAJOR ROLE IN THE LOSS AND TRANSPORT OF RADIATION BELT ELECTRONS. IT OCCURS WHEN THE DAYSIDE MAGNETOSPHERE IS COMPRESSED BY THE SOLAR WIND EXHIBITING TWO LOCAL MAGNETIC FIELD MINIMA ON EITHER SIDE OF THE EQUATOR. WHEN ELECTRONS TRAVERSE ACROSS THAT REGION THEY BECOME TEMPORARILY TRAPPED IN ONE OF THE HEMISPHERES OFF THE EQUATOR. DOB VIOLATES BOTH THE SECOND AND THIRD ADIABATIC INVARIANTS OF ELECTRONS LEADING TO FAST RADIAL TRANSPORT OF ELECTRONS FOR THEM TO BE LOST THROUGH THE MAGNETOPAUSE AND EFFICIENT PITCH ANGLE SCATTERING OF ELECTRONS FOR THE PRECIPITATION LOSS. HOWEVER THE EFFECT OF DOB HAS NOT BEEN WELL QUANTIFIED AND ITS RELATIVE IMPORTANCE TO THE LOSS AND TRANSPORT OF RADIATION BELT ELECTRONS IS NOT YET UNDERSTOOD. WE PROPOSE TO REEXAMINE AND EXTEND THE EXISTING THEORIES OF INVARIANT JUMPS AT A SINGLE BIFURCATION TO DERIVE THE LONG-TERM STATISTICAL TRANSPORT COEFFICIENTS OF RADIATION BELT ELECTRONS DUE TO MULTIPLE BIFURCATIONS. THE COEFFICIENTS FORMULAE THAT ARE APPLICABLE TO GENERAL FIELD GEOMETRIES WILL BE EVALUATED IN VARIOUS FIELD CONFIGURATIONS AND VERIFIED WITH DIRECT TEST PARTICLE SIMULATIONS USING STATE-OF-THEART MAGNETIC FIELD MODELS. THE RESULTS WILL DETERMINE IF DOB IS A DIFFUSION OR ADVECTION PROCESS OR A MIX OF BOTH AND CHARACTERIZE THE EFFECT OF DOB ON THE LOSS AND TRANSPORT OF RADIATION BELT ELECTRONS. THEN THE NEW DOB DIFFUSION AND ADVECTION COEFFICIENTS WILL BE INCORPORATED INTO THE DREAM DIFFUSION-ADVECTION MODEL TO SIMULATE THE RADIATION BELT DROPOUTS. BY COMPARING THE MODEL RESULTS WITH AND WITHOUT DOB AND AGAINST REAL-TIME OBSERVATIONS WE WILL QUANTIFY THE EFFECTS OF DOB AND DETERMINE ITS RELATIVE CONTRIBUTION TO THE DROPOUT OF RADIATION BELT ELECTRONS. THE PROPOSAL IS TIMELY FOR THE UNPRECEDENTED HIGH-RESOLUTION AND GLOBAL ENERGETIC ELECTRON AND WAVE DATA FROM NASA VAN ALLEN PROBES THEMIS AND MMS SPACECRAFT THAT COVER THE ENTIRE OUTER BELT ALL THE WAY TO THE MAGNETOPAUSE WHICH WILL PROVIDE AN EXCELLENT TEST TO OUR MODEL RESULTS. SPECIFICALLY WE WILL ADDRESS THE FOLLOWING COMPELLING SCIENCE QUESTIONS: 1. WHEN AND WHERE DOES DOB CAUSE SIGNIFICANT LOSS AND TRANSPORT OF RADIATION BELT ELECTRONS? HOW DOES THE EFFECT VARY WITH SOLAR WIND CONDITIONS GEOMAGNETIC CONFIGURATIONS ELECTRON PITCH ANGLES AND ENERGIES? 2. IS THE DOB OF RADIATION BELT ELECTRONS A DIFFUSION OR ADVECTION PROCESS OR A MIXED OF BOTH? WHAT ARE THE ELECTRON DIFFUSION AND ADVECTION RATES DUE TO DOB? 3. WHAT IS THE RELATIVE IMPORTANCE OF DOB FOR THE DROPOUT OF RADIATION BELT ELECTRONS COMPARED WITH OTHER LOSS MECHANISMS? THE PROPOSED WORK DIRECTLY ADDRESSES THE 2ND SCIENCE GOAL OF THE HELIOPHYSICS DECADAL SURVEY THAT IS "DETERMINE THE DYNAMICS AND COUPLING OF EARTH'S MAGNETOSPHERE IONOSPHERE AND ATMOSPHERE AND THEIR RESPONSE TO SOLAR AND TERRESTRIAL INPUTS". IT IS ALSO RELEVANT TO THE 4TH GOAL "DISCOVER AND CHARACTERIZE FUNDAMENTAL PROCESSES THAT OCCUR BOTH WITHIN THE HELIOSPHERE AND THROUGHOUT THE UNIVERSE" SINCE DOB IS A FUNDAMENTAL PROCESS THAT OCCURS UNIVERSALLY.