OUR OBJECTIVES ARE: 1. DETERMINE USING DATA AND A PHYSICS-BASED DRIFT MODEL HOW MAGNETOSPHERIC PLASMA EVOLVES FROM LOW TO HIGH L-SHELL AND DETERMINE THE PROCESSES THAT INFLUENCE THIS EVOLUTION (E.G. FROM CHANGES IN COMPOSITION ENERGY PITCH ANGLE ETC.). 2. QUANTIFY HOW THE IONS AFFECT THE RATE OF RECONNECTION AT THE DAYSIDE (E.G. BY CALCULATING THE PERCENTAGE REDUCTION IN THE RECONNECTION RATE AS A FUNCTION OF ACTIVITY AND SOLAR WIND CONDITIONS). 3. REVEAL THE RELATIVE EFFECTS OF THE ION PLASMA CLOAK THE PLASMASPHERIC PLUME AND THE LLBL PLASMA ON THE DAYSIDE RECONNECTION RATE (E.G. BY COMPARING THE RATE FOR PLUME PLASMA WITH THAT FOR CLOAK PLASMA AND LLBL PLASMA). THE PROPOSAL IS RELEVANT TO THREE DECADAL SURVEY GOALS: DETERMINE THE DYNAMICS AND COUPLING OF EARTH S MAGNETOSPHERE IONOSPHERE AND ATMOSPHERE AND THEIR RESPONSE TO SOLAR AND TERRESTRIAL INPUTS; DETERMINE THE INTERACTION OF THE SUN WITH THE SOLAR SYSTEM AND THE INTERSTELLAR MEDIUM; DISCOVER AND CHARACTERIZE FUNDAMENTAL PROCESSES THAT OCCUR BOTH WITHIN THE HELIOSPHERE AND THROUGHOUT THE UNIVERSE. .THE METHODOLOGY CONSISTS OF: (I) STATISTICAL STUDIES OF IONS IN THE INNER MAGNETOSPHERE AND AT THE RECONNECTION SITE (E.G. AS A FUNCTION OF L MLT AND ACTIVITY); (II) CONJUNCTION EVENT STUDIES WHERE TWO OR MORE OF THE MMS VAP AND LANL SATELLITES ARE CLOSE TO EACH OTHER AND WHEN SPACECRAFT ARE WIDELY SEPARATED BUT ON THE SAME DRIFT PATH; (III) DRIFT MODELING OF IONS AS THEY MOVE FROM INNER TO OUTER MAGNETOSPHERE DURING THESE EVENTS. FOR THE CONJUNCTIONS WE DETERMINE AND QUANTIFY IF AND HOW THE ION POPULATION EVOLVES DURING ITS DRIFT. ULTIMATELY THIS METHODOLOGY WILL LEAD TO QUANTIFICATION OF THE REDUCTION OF THE DAYSIDE MAGNETIC RECONNECTION RATE THAT RESULTS FROM THE PRESENCE OF MAGNETOSPHERIC IONS AT THE DAYSIDE RECONNECTION SITE. .