ONE OF THE LIMITING SOURCES OF ERROR IN ESTABLISHING A ROBUST STABLE GLOBAL TERRESTRIAL REFERENCE FRAME (TRF) SUITABLE FOR MODERN ACCURACY GOALS (E.G. PLAG AND PEARLMAN 2009) IS THE LOCAL GEODETIC TIES (ALTAMIMI ET AL. 2016). THE DISAGREEMENT BETWEEN LOCAL TIES AND SPACE GEODESY SOLUTIONS IS GENERALLY SIGNIFICANTLY LARGER THAT THE FORMAL UNCERTAINTIES OF THE LOCAL SURVEYS AND IS LIKELY ASSOCIATED WITH THE DIFFICULTY OF LOCATING PHYSICALLY INACCESSIBLE INSTRUMENTAL REFERENCE POINTS (E.G. ALTAMIMI ET AL. 2007 2016). THE SOLUTION IN MULTITECHNIQUE REFERENCE-FRAME COMBINATIONS USED TO PRODUCE THE INTERNATIONAL TERRESTRIAL REFERENCE FRAME (ITRF) (ALTAMIMI ET AL. 2016) IS SIMPLY TO DOWNWEIGHT THE LOCAL SURVEYS (WHICH ARE INCLUDED IN THE COMBINATION AS OBSERVATIONS) THUS PLACING MORE RELATIVE WEIGHT ON THE SPACE GEODETIC TECHNIQUES. IN ESSENCE THE ACCURACY OF THE INDIVIDUAL GEODETIC TECHNIQUES IS USED TO IMPROVE THE ESTIMATES OF THE LOCAL TIES.THERE ARE THUS TWO APPROACHES THAT CAN BE USED TO INCREASE THE ACCURACY OF THE TRF AND OF THE TIES BETWEEN TECHNIQUES: (1) DEVELOP METHODS THAT CAN REDUCE OR ELIMINATE THE SYSTEMATIC ERRORS ASSOCIATED WITH LOCAL TIES; OR (2) IMPROVE THE ACCURACY --OR MORE CORRECTLY THE CONSISTENCY-- OF THE RELATIVE POSITIONS FROM GEODETIC TECHNIQUES. THE FIRST APPROACH LIKELY BEING EXPENSIVE AND PERHAPS IMPOSSIBLE SHORT OF A SATELLITE-BASED APPROACH WE PROPOSE A METHOD THAT USES THE LATTER APPROACH TO ACHIEVE IMPROVED ACCURACY OF THE TRF COMBINATION THROUGH CONSTRAINTS BASED ON LOCAL ATMOSPHERIC STRUCTURE AT MULTI-TECHNIQUE SITES. ITRF-LIKE COMBINATIONS DO NOT CURRENTLY TAKE ADVANTAGE OF ATMOSPHERIC STRUCTURE; DOING SO COULD SIGNIFICANTLY ENHANCE SOLUTION STRENGTH INCLUDING ACCURACY OF LOCAL SYSTEM TIES ESTIMATED DURING COMBINATION. THE PROPOSED APPROACH IS DESIGNED TO TAKE ADVANTAGE OF THE INTEGRATION THAT COULD BE ACHIEVE AT THE FUTURE MULTI-TECHNIQUE CORE GEODETIC SITES OF NASA'S SPACE GEODESY PROJECT (SGP). THE RESULTS OF THE PROPOSED RESEARCH MAY HELP TO GUIDE OVERALL DESIGN FOR THESE SITES.OUR PROPOSED RESEARCH WILL EXPLORE TRADE-OFFS IN ACCURACY VERSUS MODEL COMPLEXITY AND PROPOSE REASONABLE APPROACHES TO COMBINATION THAT IMPROVES INFORMATION FROM MULTI-TECHNIQUE COMBINATIONS. THE APPROACH WILL TAKE ADVANTAGE BOTH OF KNOWN STOCHASTIC (I.E. TURBULENT) STRUCTURE AS WELL AS SYSTEMATIC (E.G. FRONTS GRADIENTS) ATMOSPHERIC STRUCTURE TO DEVELOP A PROCEDURE FOR APPLYING ATMOSPHERIC CONSTRAINTS AT THE TIME OF TRF COMBINATION. THE APPROACH REQUIRES EXPANDING THE NORMAL EQUATIONS TO INCLUDE A SET OF ATMOSPHERIC PARAMETERS AND OUR RESEARCH WILL EXPLORE WHAT ATMOSPHERIC PARAMETERS WOULD BE REQUIRED. WE ALSO PROPOSE A LIMITED PROOF-OF-CONCEPT STUDY TO ASSESS THE NEW MODELS AND ALGORITHMS.THE PROPOSED RESEARCH ADDRESSES THE GEODETIC SYSTEM TIES TOPIC OF THIS SOLICITATION BUT IS ALSO RELEVANT TO THE NETWORK ARCHITECTURE TOPIC.