OBJECTIVES WE PROPOSE TO RESOLVE THE ROLE OF MOIST CONVECTION IN THE ATMOSPHERIC CIRCULATION AND GLOBAL HYDROLOGIC CYCLE OF TITAN WHOSE EXISTENCE AND IMPORTANCE HAS BEEN INFERRED OBSERVATIONALLY AND THROUGH NUMERICAL SIMULATIONS. TROPOSPHERIC METHANE CLOUDS INDICATE A SEASONAL CYCLE THAT RECENT GENERAL CIRCULATION MODELS (GCMS) REPRODUCE. HOWEVER THESE MODELS LACK ROBUST REPRESENTATIONS OF MOIST CONVECTION WHICH IS LIKELY RESPONSIBLE FOR GENERATING MOST OF THESE CLOUDS AND INSTEAD EITHER IGNORE IT OR PARAMETERIZE IT WITH A SIMPLIFIED ADJUSTMENT SCHEME. MODEL-PREDICTED PRECIPITATION IS ONLY IN APPROXIMATE AGREEMENT WITH OBSERVED CLOUDS AND ONLY UNDER SPECIFIC CIRCUMSTANCES. MOREOVER THE INTERACTION BETWEEN THE LARGE-SCALE CIRCULATION AND THE METHANE CYCLE DEPENDS ON THE SPECIFIC TREATMENT OF THE PHASE-CHANGE OF THE CONDENSABLE WHICH AFFECTS THE OUTFLOW LEVEL OF CONVECTION AND THEREFORE THE HUMIDIFICATION OF THE MIDDLE TROPOSPHERE. ON THE OTHER HAND TITAN CLOUD-RESOLVING MODELS EXPLICITLY SIMULATE CONVECTION INCLUDING PROCESSES LIKE ENTRAINMENT THAT GCMS CANNOT RESOLVE. THESE MODELS WHICH MUST BE INITIATED WITH A BACKGROUND ATMOSPHERIC STATE SHOW THAT THE INTENSITY DEPTH AND RESULTING PRECIPITATION OF THE ENSUING CONVECTION DEPENDS ON THE ENVIRONMENT. THERE IS THEREFORE A FEEDBACK BETWEEN MOIST CONVECTION AND THE GLOBAL CIRCULATION LINKING THE TWO WITHIN THE HYDROLOGIC CYCLE WHICH WE PROPOSE TO INVESTIGATE. RAYLEIGH DISTILLATION MODELING SUGGESTS THAT PRECIPITATING CONVECTION ENHANCES THE D/H RATIO OF METHANE VAPOR BY TENS OF PERMIL ON TITAN. THEREFORE GROUND-BASED OBSERVATIONS OF FRACTIONATION CAN BE USED TO CONSTRAIN THE OUTFLOW LEVELS OF CONVECTION PROVIDING A TOOL FOR VALIDATING OUR MODELS. METHODOLOGY WE WILL USE TWO VALIDATED AND PUBLISHED NUMERICAL MODELS FOR THIS WORK: THE CLOUD-RESOLVING TITAN REGIONAL ATMOSPHERIC MODELING SYSTEM (TRAMS) AND THE TITAN ATMOSPHERIC MODEL (TAM) GCM. WE WILL MODEL AND ANALYZE CONVECTION WITH TRAMS USING INITIAL SPECIFIED BACKGROUND STATES FROM CHARACTERISTIC TAM RESULTS OF ATMOSPHERIC TEMPERATURE HUMIDITY AND WIND FIELDS. WE WILL THEN USE THE RESULTS TO EVALUATE ADJUST AND CALIBRATE THE CONVECTION PARAMETERIZATION IN TAM IN ORDER TO MOST ACCURATELY CAPTURE THE EFFECTS OF UNRESOLVED PHYSICS ON THE LARGE-SCALE FIELDS. THIS APPROACH HAS BEEN USED IN EARTH MODELING AND IS PARTICULARLY VALUABLE IN APPLICATION TO TITAN WHERE OBSERVATIONAL DATA OF CONVECTION ARE SCARCE. THE RESULTING IMPACTS ON THE LARGE-SCALE CIRCULATION AND THE GLOBAL METHANE CYCLE WILL BE INVESTIGATED. FINALLY WE WILL IMPLEMENT A SIMPLE FRACTIONATION MODEL IN TAM TO TRACK THE FRACTIONATION OF METHANE VAPOR AND COMPARE TO EXISTING GROUND-BASED OBSERVATIONS. RELEVANCE THIS WORK IS RELEVANT TO THE SOLAR SYSTEM WORKINGS PROGRAM BY INVESTIGATING PHYSICAL PROCESSES OCCURRING WITHIN THE SOLAR SYSTEM. IT IS RESPONSIVE TO THE AREA OF PLANETARY ATMOSPHERES PARTICULARLY TO THE THEMES OF COMPOSITION AND EVOLUTION AND DYNAMICS AND THERMAL STRUCTURE. WE WILL CHARACTERIZE VERTICAL MIXING AND PROFILES OF METHANE AND ITS ISOTOPES IN THE ATMOSPHERE OF TITAN AS WELL AS ACCURATELY DESCRIBE CLOUD FEATURES AND THEIR TEMPORAL VARIABILITY AND THE ROLE OF METHANE IN THE VERTICAL STRUCTURE OF AND TRANSPORT IN TITAN S ATMOSPHERE. WE NOTE THAT WHILE IT IS IN PART MOTIVATED BY THE SPECTACULAR DISCOVERIES MADE BY CASSINI THE PROPOSED WORK WILL NOT INVOLVE ANALYSIS OR NEW DIRECT USE OF DATA FROM THAT MISSION.