DEEP MOIST CONVECTION CAN AFFECT THE CONCENTRATION AND DISTRIBUTION OF TRACE GASES IN THE UPPER TROPOSPHERE AND LOWER STRATOSPHERE (UTLS) WHICH IS IMPORTANT FOR ATMOSPHERIC CHEMISTRY EARTHS RADIATION BUDGET AND CLIMATE. FOR EXAMPLE THE RADIATIVE FORCING OF CLIMATE BY GREENHOUSE GASES SUCH AS OZONE AND WATER VAPOR HAS BEEN SHOWN TO VARY SIGNIFICANTLY WITH CHANGES IN THEIR DISTRIBUTION AND CONCENTRATION NEAR THE TROPOPAUSE. DUE PRIMARILY TO THE CONTRAST IN THE COMPOSITION OF THE TROPOSPHERE AND STRATOSPHERE PROCESSES LEADING TO STRATOSPHERE-TROPOSPHERE EXCHANGE (STE) OFTEN RESULT IN THE LARGEST AND MOST RAPID CHANGES IN UTLS COMPOSITION. HOWEVER THE GLOBAL IMPACT OF SMALL-SCALE PROCESSES SUCH AS CONVECTION ON UTLS COMPOSITION IS UNKNOWN DUE TO A LIMITED UNDERSTANDING OF THEIR GEOGRAPHIC DISTRIBUTION FREQUENCY AND ADDITIONAL CHARACTERISTICS. THIS STUDY SEEKS TO IMPROVE OUR UNDERSTANDING OF CONVECTIVE INFLUENCE USING A UNIQUE COMBINATION OF GROUND-BASED RADAR OBSERVATIONS TRACE GAS PROFILES FROM THE MICROWAVE LIMB SOUNDER (MLS) ABOARD THE NASA AURA SATELLITE AND ASSIMILATED ATMOSPHERIC STATES FROM THE NASA MODERN ERA RETROSPECTIVE ANALYSIS FOR RESEARCH AND APPLICATIONS VERSION 2 (MERRA-2). THE EFFORTS IN THIS PROPOSAL WILL TEST A KEY HYPOTHESIS: CONVECTION IS A SIGNIFICANT CONTRIBUTOR TO CHANGES IN THE COMPOSITION OF THE UTLS OVER LARGE SPATIAL SCALES (I.E. REGIONALLY AND/OR GLOBALLY). THROUGH EXAMINING THE VALIDITY OF THIS HYPOTHESIS WE SEEK TO DETERMINE: (1) THE RELATIONSHIP BETWEEN THE PHYSICAL CHARACTERISTICS OF CONVECTION THE THERMODYNAMIC CHARACTERISTICS OF ITS ENVIRONMENT AND ITS IMPACT ON THE COMPOSITION OF THE UTLS (2) THE SEASONALITY OF THE LOCATION FREQUENCY MAGNITUDE AND DEPTH OF CONVECTIVE INFLUENCE OVER THE CONTIGUOUS UNITED STATES AND ITS IMPLICATIONS FOR RADIATION AND CLIMATE AND (3) THE RELATIVE ROLES OF TROPOSPHERIC TRANSPORT STE AND CHEMICAL PROCESSES SUCH AS STRATOSPHERIC OZONE DEPLETION IN ESTABLISHING THE OBSERVED UTLS COMPOSITION LINKED WITH CONVECTION. THE KEY HYPOTHESIS AND RELATED OBJECTIVES WILL BE ADDRESSED USING TRAJECTORY MAPPING TECHNIQUES DRIVEN BY MERRA-2 WINDS. IN PARTICULAR TRAJECTORIES WILL BE USED TO LINK CONVECTION AND CLOUD-FREE REGIONS OVER THE UNITED STATES IDENTIFIED IN A NEW HIGH RESOLUTION HIGH-FREQUENCY DATABASE OF OBSERVATIONS FROM THE U.S. NEXRAD WSR-88D GROUND-BASED PRECIPITATION RADAR NETWORK WITH DOWNSTREAM AURA MLS PROFILES. THE TWO POPULATIONS OF MLS PROFILES WILL THEN BE COMPARED TO DETERMINE THE INFLUENCE OF CONVECTION ON THE COMPOSITION OF THE UTLS. THESE ANALYSES WILL ADVANCE OUR UNDERSTANDING OF CONVECTIVE INFLUENCE AND ITS IMPACT ON CHEMISTRY AND CLIMATE. THE PROPOSED EFFORT WILL SUPPORT NASAS INTERNATIONAL LEADERSHIP AS A DISCOVERY ORGANIZATION BY USING AND PROMOTING THE USE OF UNIQUE NASA DATASETS AND BY BUILDING OFF OF PREVIOUS NASA ACCOMPLISHMENTS. IN ADDITION BY INCREASING OUR UNDERSTANDING OF CONVECTIVE INFLUENCE ON UTLS COMPOSITION THIS STUDY WILL SUPPORT TWO PRIMARY OBJECTIVES OF NASAS MISSION IN EARTH SYSTEM SCIENCE: (1) TO ADVANCE THE UNDERSTANDING OF CHANGES IN THE EARTH'S RADIATION BUDGET THAT RESULT FROM CHANGES IN ATMOSPHERIC COMPOSITION AND (2) TO IMPROVE THE ABILITY TO PREDICT CLIMATE CHANGES BY BETTER UNDERSTANDING THE ROLE OF THE ATMOSPHERE IN THE CLIMATE SYSTEM