IN ORDER TO BETTER UNDERSTAND THE MARTIAN THERMOSPHERE AND THE DYNAMICAL THERMAL AND CHEMICAL PROCESSES ACTING WITHIN IT WIND PATTERNS IN THIS REGION OF THE ATMOSPHERE NEED TO BE ACCURATELY DESCRIBED. THUS THE GOAL OF THIS PROJECT IS TO UNDERSTAND WHICH PHYSICAL PROCESSES ARE IMPORTANT IN DRIVING NEUTRAL WINDS AND THEIR VARIABILITY IN THE UPPER ATMOSPHERE OF MARS. THIS STUDY IS MOTIVATED BY A UNIQUE NEW DATASET OF THERMOSPHERIC WIND OBSERVATIONS - THE FIRST IN-SITU OBSERVATIONS OF NEUTRAL WINDS AT THESE ALTITUDES - FROM THE NEUTRAL GAS AND ION MASS SPECTROMETER (NGIMS) ON THE MARS ATMOSPHERE AND VOLATILE EVOLUTION (MAVEN) SPACECRAFT CURRENTLY ORBITING MARS. THIS WIND DATASET WILL BE USED TO HELP CONSTRAIN A GENERAL CIRCULATION MODEL THE MARS GLOBAL IONOSPHERE-THERMOSPHERE MODEL (M-GITM) AS NEW PHYSICAL PROCESSES ARE INCORPORATED INTO THE MODEL IN ORDER TO BETTER REPLICATE AND UNDERSTAND THE OBSERVED THERMOSPHERIC WINDS. SPECIFICALLY A NEW GRAVITY WAVE PARAMETERIZATION AND A TIME DEPENDENT DUST SCHEME WILL BE INCORPORATED AND TESTED IN M-GITM. THE RESULTING SIMULATIONS WILL THEN BE COMPARED TO THE NGIMS WIND OBSERVATIONS. THIS METHOD WILL HELP REVEAL THE RELATIVE IMPORTANCE OF THESE PROCESSES IN DRIVING THERMOSPHERIC WINDS COMPARED TO EACH OTHER AND SOLAR FORCING. IN ADDITION NGIMS NEUTRAL WIND OBSERVATIONS SPANNING A RANGE OF CONDITIONS INCLUDING DIFFERENT SEASONS WILL BE ANALYZED AND COMPARED TO CORRESPONDING M-GITM SIMULATIONS TO EXAMINE THE VARIABILITY OF THE WINDS. THUS THE CENTRAL OBJECTIVES THAT WILL BE ADDRESSED IN THIS RESEARCH ARE: (1) TO ADD PHYSICAL PROCESSES TO M-GITM WHICH ARE KNOWN TO BE LACKING OR OVERLY SIMPLIFIED SPECIFICALLY THROUGH A NEW GRAVITY WAVE PARAMETERIZATION AND TIME DEPENDENT DUST SCHEME AND (2) TO DETERMINE WHICH PHYSICAL PROCESSES ARE COMPARATIVELY MORE SIGNIFICANT IN DRIVING THERMOSPHERIC WINDS AND UNDER WHAT ENVIRONMENTAL CONDITIONS BY COMPARING MODEL SIMULATIONS WITH NGIMS WIND OBSERVATIONS. THIS PROJECT DIRECTLY ADDRESSES ONE OF THE MAIN GOALS OF THE MAVEN MISSION BY WORKING TO UNDERSTAND THE CURRENT STATE OF THE MARTIAN UPPER ATMOSPHERE AND THE PROCESSES CONTROLLING IT. THE PROPOSED WORK IS SIMILARLY RELEVANT TO THE PLANETARY SCIENCE DIVISION AT NASA AS IT WILL ADVANCE THE UNDERSTANDING OF THE PHYSICAL PROCESSES ACTING AT PLANETS IN THE SOLAR SYSTEM AND SPECIFICALLY AT MARS. NAMELY THIS RESEARCH IS SIGNIFICANT TO THE INTERESTS OF NASA AS IT WILL INVESTIGATE THE PROPERTIES OF THE MARTIAN ATMOSPHERE AND WILL ENHANCE THE RETURN OF THE MAVEN MISSION THROUGH ANALYSIS OF THE NGIMS NEUTRAL WIND DATASET TOGETHER WITH SIMULATIONS FROM A GENERAL CIRCULATION MODEL.