THE DUNGEY CYCLE IS ONE OF THE MOST FUNDAMENTAL CONCEPTS OF SPACE PHYSICS AND THE DISTANT PLASMA SHEET (PS) IS ITS FIRST SEGMENT IN THE CLOSED FIELD-LINE REGION OF THE MAGNETOSPHERE. IN THIS PROJECT WE WILL INVESTIGATE THE PLASMA CONVECTION IN THE DISTANT PS WITH AN EMPHASIS ON MAGNETIC FLUX TRANSPORT. MORE SPECIFICALLY BY OBSERVATIONALLY ADDRESSING THE FOLLOWING THREE SCIENCE QUESTIONS (SQS) WE WILL SEEK TO PROVIDE NEW INSIGHTS INTO ELECTRODYNAMIC COUPLING OF THE DISTANT PS WITH OTHER AREAS OF THE SOLAR WIND-MAGNETOSPHEREIONOSPHERE (SW-M-I) SYSTEM: SQ1) HOW IS THE CONVECTION IN THE DISTANT PS STATISTICALLY CHARACTERIZED? SQ2) HOW DOES THE CONVECTION IN THE DISTANT PS RESPOND TO THE ENHANCEMENT OF THE SOLAR WIND DRIVING? SQ3) WHAT IS THE IONOSPHERIC MANIFESTATION OF THE CONVECTION ENHANCEMENT IN THE DISTANT PS? WE WILL USE AS A PRIMARY DATA SET PLASMA MAGNETIC FIELD AND ELECTRIC FIELD MEASUREMENTS MADE BY THE ARTEMIS SPACECRAFT. WE WILL ALSO USE OTHER DATA SETS SUCH AS THE SAME MEASUREMENTS BUT MADE BY THE THEMIS NEAR-EARTH PROBES THE OMNI SOLAR WIND AND IMF DATA AND ALL-SKY IMAGER (ASI) DATA FROM THEMIS GROUND BASED OBSERVATORY STATIONS. SINCE THE EQUATORIAL MAGNETIC FIELD IS USUALLY VERY WEAK IN THE DISTANT PS THE FLOW VELOCITY IS NOT ALWAYS AN APPROPRIATE MEASURE OF CONVECTION. IN THIS PROJECT WE WILL ADDRESS THE PS CONVECTION MOSTLY IN TERMS OF THE TRANSPORT RATE OF MAGNETIC FLUX TRANSPORT THAT IS ELECTRIC FIELD. THE FOLLOWING IS THE DESCRIPTION OF OUR APPROACH TO EACH SCIENCE QUESTION. - FOR SQ1 WE WILL CALCULATE THE PROBABILITY DENSITY FUNCTIONS OF V_PERP AND E (OR -VXB) MEASURED BY ARTEMIS. AN EMPHASIS WILL BE PLACED ON THE RELATIVE CONTRIBUTION OF BURSTY TRANSPORT. BY COMPARING WITH THE PREVIOUSLY REPORTED RESULTS OF THE NEAR-EARTH PS WE WILL ADDRESS THE ROLE OF DISTANT RECONNECTION IN THE EARTHWARD TRANSPORT OF MAGNETIC FLUX. WE WILL ALSO MAKE A SIMILAR COMPARISON WITH MEASUREMENTS MADE AT R<12 RE BY THE THEMIS NEAR-EARTH PROBES DURING THE SAME PERIOD AS ARTEMIS. - FOR SQ2 WE WILL SELECT SOUTHWARD IMF TURNINGS USING THE OMNI DATA. WE WILL CONDUCT A SUPERPOSED EPOCH ANALYSIS WITH THE SOUTHWARD TURNING AS A REFERENCE TIME AND WILL ADDRESS WHEN AND IN WHAT FORM (I.E. BURSTY VS. STEADY) THE CONVECTION ENHANCES IN THE DISTANT PS. WE WILL ALSO EXAMINE IF THE CONVECTION ENHANCEMENT IS PRECEDED BY A CERTAIN PERIOD OF ENERGY STORAGE. - FOR SQ3 USING THE GROUND ASI DATA TAKEN DURING CONVECTION ENHANCEMENT EVENTS OBSERVED BY ARTEMIS WE WILL EXAMINE WHAT AURORAL FORMS CORRESPONDS TO THE CONVECTION ENHANCEMENT AND HOW IT DEVELOPS SPATIALLY (I.E. LONGITUDINALLY OR EQUATORWARD). THE RESULT WILL BE ADDRESSED IN THE CONTEXT OF THE RECENTLY PROPOSED SEQUENCE OF SUBSTORM INITIATION WITH AN EMPHASIS ON THE POSSIBLE LINK BETWEEN THE DISTANT RECONNECTION AND THE POLEWARD BOUNDARY INTENSIFICATIONS (PBIS) OF AURORAL EMISSION. BY SYNTHESIZING THE RESULTS OF THOSE PROPOSED STUDIES WE WILL PROVIDE A NEW LEVEL OF UNDERSTANDING OF THE ELECTRODYNAMIC LINK OF THE DISTANT MAGNETOTAIL WITH OTHER AREAS OF THE SW-M-I SYSTEM. THE SUBJECT OF THIS PROJECT THE ELECTRODYNAMICS OF THE DISTANT PS IS COHERENT WITH THE ONE OF THE SCIENCE TARGETS OF THE ARTEMIS MISSION THAT IS MAGNETOTAIL-SOLAR WIND INTERACTION. THIS PROJECT WILL SIGNIFICANTLY ENHANCE ITS SCIENTIFIC OUTPUT BY INVESTIGATING THE LINK OF THE DISTANT PS WITH THE NEAR-EARTH PS (SQ1) SOLAR WIND (SQ2) AND IONOSPHERE (SQ3). THE SUBJECT IS ALSO CLOSELY RELATED TO THE MAGNETOTAIL RECONNECTION AND SUBSTORM INITIATION SEQUENCE WHICH ARE THE TARGETS OF THE MMS AND THEMIS MISSIONS RESPECTIVELY. THE PROPOSED RESEARCH WILL STUDY THE DISTANT MAGNETOTAIL FROM THE VIEWPOINT OF THE SW-M-I COUPLING AND THEREFORE IT IS COHERENT WITH THE GOAL OF THE HELIOPHYSICS SYSTEM OBSERVATORY AND MORE GENERALLY WITH A HIGH-LEVEL SCIENCE GOAL OF HELIOPHYSICS DECADAL SURVEY.
$415,871FY2020National Aeronautics and Space AdministrationNASA
The Johns Hopkins University