SCIENCE GOALS&OBJECTIVES: A LARGE NUMBER OF KEY PROCESSES THAT SHAPE THE OVERALL STRUCTURE AND COMPOSITION OF THE MIDDLE AND UPPER ATMOSPHERE INCLUDE GRAVITY TIDAL AND PLANETARY WAVES. THE MESOSPHERE-LOWER THERMOSPHERE (MLT) REGION IS THE PRIMARY REGION WHERE THE ATMOSPHERIC WAVES BREAK AND GENERATE TURBULENCE; THE AMOUNT OF ENERGY TRANSFERRED INTO THE MESOSPHERE IS COMPARABLE TO THE AMOUNT OF ENERGY ABSORBED FROM THE SUN. OUR MAIN OBJECTIVE IS TO UNDERSTAND THE EXTENT TO WHICH THE LONGITUDINAL LATITUDINAL AND SEASONAL LOCATION OF THE MESOPAUSE IMPACTS VARIABILITY IN IONOSPHERIC ELECTRON DENSITY BY PRODUCING VARIATIONS OF ATOMIC OXYGEN. THIS PROJECT WILL EXAMINE THE GEOGRAPHY OF THE MESOPAUSE I.E. THE REGION WHERE VERTICAL SHEARS IN THE ZONAL WINDS ARE SIGNIFICANT AND THE TEMPERATURE IS THE COLDEST. IT WILL INVESTIGATE TO WHAT DEGREE VARIATIONS IN TEMPERATURE AND THE HEIGHT OF THE MESOPAUSE ARE LINKED TO THE DENSITY OF ATOMIC OXYGEN IN THE MLT REGION AND TO THE O/N2 RATIO IN THE THERMOSPHERE. AS THE DAYTIME IONOSPHERIC ELECTRON DENSITY DIRECTLY DEPENDS ON THE O/N2 RATIO THE PROJECT WILL INVESTIGATE TO WHAT DEGREE REGIONAL ANOMALIES IN IONOSPHERIC ELECTRON DENSITY CAN BE EXPLAINED BY REGIONAL VARIATIONS IN THERMOSPHERIC COMPOSITION. MISSION DATA: TO CARRY OUT THE PROPOSED WORK WE WILL EMPLOY OBSERVATIONAL DATA THAT RANGE FROM THE STRATOSPHERE TO THE IONOSPHERE FROM VARIETY OF NASA MISSIONS AND PROJECTS. WE WILL USE TIMED SABER TIMED GUVI AIM SOFIE EOS MLS AS WELL AS NASA MERRA-2 REANALYSIS PRODUCTS. WE WILL ALSO EMPLOY GROUND-BASED MEASUREMENTS FROM GNSS TEC RECEIVERS IONOSONDES INCOHERENT SCATTER RADARS AND FPIS. METHODOLOGY: TIMED SABER TEMPERATURE DATA WILL BE USED TO CREATE A NOVEL CLIMATOLOGY OF THE MESOPAUSE THAT VARIES AS A FUNCTION OF LATITUDE LONGITUDE LOCAL TIME AND DAY OF YEAR. AIM SOFIE WILL PROVIDE INDEPENDENT CONFIRMATION OF ZONAL ASYMMETRIES IN MESOPAUSE TEMPERATURE OBSERVED BY SABER BUT WITH HIGH VERTICAL RESOLUTION. TIMED SABER ATOMIC OXYGEN OBSERVATIONS AND TIMED GUVI O/ N2 DATA WILL BE USED JOINTLY TO UNDERSTAND THE VERTICAL EXTENT OF VARIATIONS IN COMPOSITION OF THE LOWER THERMOSPHERE. WE WILL EXPLORE RELATIONSHIPS BETWEEN REGIONAL MESOPAUSE FLUCTUATIONS AND GUVI TEMPERATURE AND O/N2 VARIABILITY IN THE THERMOSPHERE. EXTENDING THE ATMOSPHERIC COLUMN DOWN THROUGH THE POLAR VORTEX WILL BE DONE WITH MERRA-2 REANALYSIS WINDS FOR CONNECTIONS WITH SUDDEN STRATOSPHERIC WARMINGS. WE WILL USE EOS MLS CO DATA TO DEFINE THE VORTEX IN THE MESOSPHERE. GNSS TEC AND IONOSONDE DATA WILL BE USED TO EXAMINE ANOMALIES IN IONOSPHERIC ELECTRON DENSITY AND THEIR CONNECTION WITH THERMOSPHERIC COMPOSITION. EMPIRICAL MODELS OF GPS TEC AND PEAK ELECTRON DENSITY (NMF2) WILL BE USED TO ISOLATE REGIONAL IONOSPHERIC ANOMALIES NOT RELATED TO CHANGES IN SOLAR FLUX SEASON AND GEOMAGNETIC ACTIVITY. OBSERVATIONS FROM GROUND-BASED INCOHERENT SCATTER RADARS AND FPIS WILL SUPPLEMENT PROPOSED RESEARCH. RELEVANCE TO NASA UNDERSTANDING THE SOURCE OF VARIABILITY IN UPPER ATMOSPHERIC PARAMETERS IS A RECOMMENDED PRIORITY OF THE HELIOPHYSICS COMMUNITY DISCUSSED IN THE HELIOPHYSICS ROADMAP FOR SCIENCE AND TECHNOLOGY 2009-2030: WHAT IS RESPONSIBLE FOR THE DRAMATIC VARIABILITY IN MANY OF THE STATE VARIABLES DESCRIBING THE IONOSPHERE-THERMOSPHERE-MESOSPHERE REGION? AND HOW DO COUPLED MIDDLE AND UPPER ATMOSPHERE RESPOND TO EXTERNAL DRIVERS AND TO EACH OTHER? . THIS EFFORT IS RELEVANT TO THE TWO HIGH-LEVEL SCIENCE GOALS FROM THE MOST RECENT HELIOPHYSICS DECADAL SURVEY SOLAR AND SPACE PHYSICS: A SCIENCE FOR A TECHNOLOGICAL SOCIETY 1) DETERMINE THE DYNAMICS AND COUPLING OF EARTH S MAGNETOSPHERE IONOSPHERE AND ATMOSPHERE AND THEIR RESPONSE TO SOLAR AND TERRESTRIAL INPUTS AND 2) DISCOVER AND CHARACTERIZE FUNDAMENTAL PROCESSES THAT OCCUR BOTH WITHIN THE HELIOSPHERE AND THROUGHOUT THE UNIVERSE. THE PROJECT IS ALSO RELEVANT TO THE 2 SCIENCE AREAS: 11. IONOSPHERE ATMOSPHERE COUPLING AND 12. NEUTRAL ATMOSPHERE