EARTHS THERMOSPHERE AND IONOSPHERE ARE STRONGLY INFLUENCED BY THE ENERGY AND MOMENTUM INPUT FROM THE MAGNETOSPHERE. THIS INPUT GREATLY DEPENDS ON SOLAR WIND AND INTERPLANETARY MAGNETIC FIELD (IMF) CONDITIONS THAT DETERMINES HIGH-LATITUDE IONOSPHERIC CONVECTIVE ELECTRIC FIELDS PARTICLE PRECIPITATION AND JOULE HEATING. IN PREVIOUS WORK THERMOSPHERIC TEMPERATURE WINDS AND COMPOSITION HAVE BEEN PRIMARILY STUDIED UNDER GEOMAGNETICALLY ACTIVE PERIODS DRIVEN BY SOUTHWARD INTERPLANETARY MAGNETIC FIELD CONDITIONS. HOWEVER THERE ARE MANY CASES WHEN THE IMF BY COMPONENT IS COMPARABLE OR LARGER THAN THE BZ COMPONENT. IN THESE CASES THE HIGH-LATITUDE CONVECTION PATTERN AND PRECIPITATION BEHAVE VERY DIFFERENTLY FROM THEIR BEHAVIOR WHEN IMF BZ IS DOMINANT. THE ENERGY AND MOMENT INPUTS FROM THE MAGNETOSPHERE AND THEIR EFFECTS ON THE STATE OF THE THERMOSPHERE AND IONOSPHERE WHEN IMF BY IS LARGE ARE ALSO VERY DIFFERENT. TO DATE THERE HAVE BEEN VERY FEW STATISTICAL AND EVENT STUDIES OF THE THERMOSPHERIC COMPOSITION CHANGES DURING IMF BY DOMINANT CONDITIONS. THIS IMPAIRS OUR UNDERSTANDING OF HOW THERMOSPHERIC COMPOSITION CHANGES DURING VARIOUS GEOPHYSICAL CONDITIONS THE PHYSICAL MECHANISM BY WHICH THESE CHANGES OCCURS AND THEIR EFFECTS ON THE IONOSPHERE. HERE WE PROPOSE TO ADDRESS THIS ISSUE BY USING NUMERICAL SIMULATIONS AND TIMED GUVI O/N2 COMPOSITION DATA TO UNDERSTAND GLOBAL STRUCTURES OF THERMOSPHERIC COMPOSITION ASSOCIATED WITH IMF BY DOMINANT CONDITIONS AND THE IONOSPHERIC DISTRIBUTIONS RELATED TO THESE CONDITIONS. THIS GOAL WILL BE ACHIEVED BY ADDRESSING THE FOLLOWING SCIENTIFIC QUESTIONS: 1) ARE THE GLOBAL STRUCTURES OF THERMOSPHERE COMPOSITION SIGNIFICANTLY DIFFERENT WHEN THE IMF BY IS LARGE? 2) DO THESE STRUCTURES CHANGE WITH SEASON AND SOLAR CYCLE? 3) ARE OTHER THERMOSPHERIC FIELDS AND THE IONOSPHERE ALSO RESPONSIVE TO IMF BY? THE TIMED GUVI O/N2 AND NO DATA AND THE COUPLED MAGNETOSPHERE IONOSPHERE AND THERMOSPHERE (CMIT) MODEL A FIRST PRINCIPLES MODEL OF THE COUPLED MAGNETOSPHERE IONOSPHERE AND THERMOSPHERE SYSTEM WILL BE USED TO ADDRESS THESE QUESTIONS. MODEL SIMULATIONS WILL BE USED TO INTERPRET SATELLITE OBSERVATIONS AND TO OBTAIN PHYSICAL INSIGHT ABOUT THE FORCES CAUSING COMPOSITION CHANGES DURING IMF BY DOMINANT CONDITIONS. BY DEVELOPING AN UNDERSTANDING OF THREE-DIMENSIONAL VARIATIONS OF THERMOSPHERIC COMPOSITION UNDER THESE CONDITIONS THIS PROPOSAL WILL PROVIDE CONTEXT FOR THE UPCOMING NASA ICON AND GOLD MISSIONS. THE IMF DATA WILL BE OBTAINED FROM THE NASA CDAWEB. THIS PROPOSED WORK USES DATASETS FROM THE ONGOING HELIOPHYSICS MISSION TIMED AND A STATE-OF-ART PHYSICS-BASED NUMERICAL MODEL. IT FITS THE KEY REQUIREMENT OF THE NASA HSR PROGRAM: TO EMPLOY A COMBINATION OF SCIENTIFIC TECHNIQUES THAT INCLUDE BOTH NUMERICAL SIMULATION AND DATA ANALYSIS AND INTERPRETATION OF NASA-SPACECRAFT OBSERVATIONS. THE PROPOSED STUDY CLOSELY ADDRESSES TWO OF THE FOUR HIGH LEVEL SCIENCE GOALS OF THE HELIOPHYSICS DECADAL SURVEY: DETERMINE THE DYNAMICS AND COUPLING OF EARTH S MAGNETOSPHERE IONOSPHERE AND ATMOSPHERE AND THEIR RESPONSE TO SOLAR AND TERRESTRIAL INPUTS ; AND DISCOVER AND CHARACTERIZE FUNDAMENTAL PROCESSES THAT OCCUR BOTH WITHIN THE HELIOSPHERE AND THROUGHOUT THE UNIVERSE .