WE PROPOSE TO CONTINUE TO PROCESS AND/OR ARCHIVE WHOLE AIR SAMPLES COLLECTED FROM AIRCRAFT AND BALLOON FLIGHTS DURING UPCOMING NASA MISSIONS AND FLIGHTS OF OPPORTUNITY FOR MEASUREMENTS OF THE ISOTOPIC COMPOSITIONS OF CHEMICALLY AND/OR RADIATIVELY IMPORTANT TRACE GASES INCLUDING CARBON DIOXIDE AND NITROUS OXIDE. THE ISOTOPE MEASUREMENTS AND THEIR ANALYSIS WILL ALLOW CONTINUED MONITORING OF ATMOSPHERIC COMPOSITION AND TRANSPORT PROCESSES IN THE STRATOSPHERE AND UPPER TROPOSPHERE OVER THE NEXT 4 YEARS FOLLOWING ON OUR MEASUREMENTS NOW DATING BACK TO NASA SUBORBITAL FLIGHTS IN 1996-1997. THE OBSERVATIONS AND COMPARISON WITH ATMOSPHERIC MODELS WILL BE USED TO BETTER UNDERSTAND AND QUANTIFY STRATOSPHERIC TRANSPORT AND MIXING STRATOSPHERIC MEAN AGES AND RESIDENCE TIMES STRATOSPHERE-TROPOSPHERE EXCHANGE (STE) MESOSPHERE-STRATOSPHERE EXCHANGE PROCESSES THAT CONTROL THE COMPOSITION OF THE TROPICAL TROPOPAUSE TRANSITION LAYER AND MIDLATITUDE UPPER TROPOSPHERE AND THE EXTENT TO WHICH STE CREATES SIGNALS AT EARTH'S SURFACE THAT COMPETE WITH SIGNALS FROM ANTHROPOGENIC AND NATURAL EMISSIONS OF CHEMICALLY AND RADIATIVELY IMPORTANT SPECIES SUCH AS OZONE NITROUS OXIDE AND CARBON DIOXIDE. INSIGHTS AND CONSTRAINTS FOR CHEMISTRY-CLIMATE MODELS WILL ALSO BE GAINED AND ENABLE BETTER PREDICTION OF HOW THESE PROCESSES MAY HAVE CHANGED IN THE PAST AND HOW THEY MAY CHANGE IN THE FUTURE WITH APPLICATIONS TO BETTER PREDICTING THE RECOVERY OF THE OZONE LAYER GREENHOUSE GAS LEVELS AND FEEDBACKS BETWEEN THEM. OVERALL THESE MEASUREMENTS AND ANALYSES WILL CONTRIBUTE TO THE STRATEGIC GOALS OF THIS SOLICITATION AND TO NASA EARTH SCIENCE GOALS IN GENERAL TO BETTER UNDERSTAND AND MONITOR ATMOSPHERIC COMPOSITION FEEDBACKS WITH CLIMATE AND HOW THESE MAY BE CHANGING OVER TIME.