THE FIELD OF EXOPLANET ATMOSPHERES HAS MATURED ENOUGH TO THE POINT WHERE WE CAN BEGIN TO ASK FUNDAMENTAL QUESTIONS REGARDING PLANETARY CLIMATE COMPOSITION ATMOSPHERE-PLANET FORMATION LINKS AND PROVIDE CONTEXT FOR UNDERSTANDING OUR OWN SOLAR SYSTEM PLANETS. THE COMMUNITY HAS LEVERAGED THE POWER OF NUMEROUS GROUND AND SPACE BASED OBSERVATORIES TO CHARACTERIZE A DIVERSE RANGE OF PLANETS RANGING FROM HOT JUPITERS TO TERRESTRIAL SIZED POTENTIALLY HABITABLE WORLDS. MUCH OF THE ATMOSPHERIC CHARACTERIZATION WORK TO DATE HAS FOCUSED ON RESULTS FROM LOW DISPERSION SPECTROSCOPY (LDS) AND PHOTOMETRY FROM SPACE-BASED INSTRUMENTS LIKE THE HUBBLE AND SPITZER SPACE TELESCOPES. WHILE WE OWE MUCH OF OUR EXOPLANETARY ATMOSPHERE INSIGHTS FROM SUCH OBSERVATIONS THEY ARE LIMITED IN THE ACCESSIBILITY OF CERTAIN MOLECULES AND ATMOSPHERIC REGIONS PROBED DUE TO LOW RESOLUTION AND SPARSE WAVELENGTH COVERAGE. JWST WILL SOLVE MANY OF THESE PROBLEMS HOWEVER IT IS A LIMITED RESOURCE AND IT IS PRUDENT THAT WE HAVE INDEPENDENT AND ROBUST ALTERNATIVE METHODS THAT LEVERAGE NUMEROUS GROUND-BASED FACILITIES AN EXCITING EMERGING APPROACH FOR CHARACTERIZING ATMOSPHERES IS HIGH DISPERSION CROSS-CORRELATION SPECTROSCOPY (HDCCS). HDCCS LEVERAGES THE LARGE NUMBER OF MOLECULAR LINES ATTAINABLE AT HIGH RESOLUTIONS (R>30 000) AND LARGE GROUND BASES APERTURES TO ROBUSTLY DETECT MOLECULES. THIS IS THE ONLY METHOD TO HAVE ROBUSTLY DETECTED CARBON-BASED MOLECULES IN TRANSITING EXOPLANET ATMOSPHERES. HOWEVER LITTLE WORK HAS FOCUSED ON THE ABILITY TO CONSTRAINT THE ABUNDANCES OF MOLECULES VERTICAL TEMPERATURE STRUCTURES AND OTHER FUNDAMENTAL ATMOSPHERIC PROPERTIES FROM HDCCS DATA IN A RIGOROUS WAY. ONE OF THE PRIMARY CHALLENGES IN DOING SO IS PLACING THE HDCCS WITHIN A ROBUST ATMOSPHERIC RETRIEVAL FRAMEWORK A WIDELY APPLIED KEY TOOL IN LDS DATA INTERPRETATION. OUR TEAM HAS RECENTLY PIONEERED PLACING HDCCS AND LDS WITHIN IN A COMMON RETRIEVAL FRAMEWORK TO MAXIMIZE ATMOSPHERIC CONSTRAINTS. ADDITIONALLY RECENTLY COMMISSIONED INSTRUMENTS SUCH AS CARMENES GIANO ISHELL IGRINS AND ESPRESSO HAVE GREATLY IMPROVED THE PROSPECTS OF ATMOSPHERIC CONSTRAINTS FROM HDCCS OBSERVATIONS. WE PROPOSE TO LEVERAGE THE POWER OF HDCCS COMBINED WITH BAYESIAN ATMOSPHERIC RETRIEVAL METHODOLOGIES TO:-DETERMINE PREVIOUSLY UNDETERMINED BAYESIAN CONFIDENCE INTERVALS ON ATMOSPHERIC PROPERTIES (MOLECULAR COMPOSITION THERMAL STRUCTURES ELEMENTAL RATIOS) DERIVED FROM CURRENT ARCHIVAL HIGH-RESOLUTION DATASETS OF TRANSITING PLANETS SUCH AS THOSE FROM VLT CRIRES AND KECK NIRSPEC. -DEVELOP A UNIFIED BAYESIAN RETRIEVAL FRAMEWORK THAT COMBINES LDS (R<~5 000 E.G. HST JWST) AND HDCCS AS WELL AS IDENTIFY THE STRENGTHS AND WEAKNESSES OF EACH METHOD. -INVESTIGATE THE POTENTIAL CONSTRAINTS FOR MOLECULES PRESUMED TO BE PRESENT IN TEMPERATE TERRESTRIAL PLANETS AND IDENTIFY HIGH RESOLUTION WAVELENGTH REGIMES THAT ARE MOST AMENABLE TO PRECISION ABUNDANCE CONSTRAINTS WITH APPLICATIONS TO THE NEXT GENERATION OF LARGE TELESCOPES LIKE TMT AND GMT. WE WILL EXPLORE THESE OBJECTIVES WITHIN THE CONTEXT OF ALL TRANSIT GEOMETRIES AND WAVELENGTH REGIMES INCLUDING TRANSMISSION EMISSION PHASE RESOLVED AND REFLECTED LIGHT. OUR TEAM IS UNIQUELY SUITED TO ACCOMPLISH THESE GOALS BOTH FROM A HDDCCS AND LDS DATA ANALYSIS PERSPECTIVE AS WELL AS THE THEORETICAL MODELING. THE PROPOSED WORK WILL DIRECTLY ADDRESS THE NASA XRP GOAL OF UNDERSTANDING EXOPLANETARY SYSTEMS BY REFINING AND STRESS TESTING THE KEY TOOLS USED TO CHARACTERIZE EXOPLANETS AND THEIR ATMOSPHERES IN ORDER TO INFORM TARGET AND OPERATIONAL CHOICES FOR CURRENT NASA MISSIONS AND/OR TARGETING OPERATIONAL AND FORMULATION DATA FOR FUTURE NASA OBSERVATORIES . APPLICATION OF THIS UNIFIED FRAMEWORK WILL ALLOW US TO GAIN A BETTER IDEA OF THE DATA REQUIRED TO UNDERSTAND THE CHEMICAL AND PHYSICAL PROCESSES OF EXOPLANETS (INCLUDING THE STATE AND EVOLUTION OF THEIR ATMOSPHERES)