FOR ATMOSPHERIC CHEMISTRY ONE OF THE GRAND CHALLENGES IS TO BUILD A QUANTITATIVE PREDICTIVE UNDERSTANDING OF THE BUDGETS OF TROPOSPHERIC OZONE (O3) AND METHANE (CH4). IN TERMS OF MANAGING CLIMATE CHANGE AND AIR QUALITY OVER THIS CENTURY WE NEED CHEMISTRY-CLIMATE MODELS (CCMS) WITH SOLID PREDICTIVE CAPABILITY. WE PROPOSE TO DEVELOP A SET OF OBSERVATION-BASED PROCESS-ORIENTED METRICS TO TEST CCMS ON THEIR ABILITY TO MATCH CONDITIONS RELATED TO THE O3 AND CH4 BUDGETS. THE CORE DATA FOR THESE METRICS WILL COME FROM THE NASA DC8 AIRCRAFT IN SITU MEASUREMENTS FROM SEVERAL RECENT CAMPAIGNS. THE MAJOR TASK IS TO BUILD AN OBSERVATIONAL DATABASE OF CHEMICAL STATISTICS INCLUDING HIGH-ORDER PRODUCTS AND CHEMICAL REACTION RATES THAT RELATE TO THESE BUDGETS. COMBINED WITH MODEL DIAGNOSTICS THESE BECOME METRICS THAT CAN TEST AND DIFFERENTIATE ACROSS THE SPECTRUM OF CCMS SO AS TO IDENTIFY GOOD PERFORMERS AND OUTLIERS. THESE METRICS WILL BE DEVELOPED AND TESTED WITH COMMUNITY INPUT AND WILL BE READY FOR THE PLANNING OF THE NEXT MAJOR CYCLE OF CLIMATE ASSESSMENTS WHICH HAVE NOW BECOME A STANDARD CYCLE FOR ATMOSPHERIC CHEMISTRY MODELS. THE OVERALL GOAL HERE IS TO PROVIDE METRICS FOR GUIDANCE IN MODEL DEVELOPMENT AND TESTING IN ORDER TO DOCUMENT IMPROVEMENTS IN OUR ATMOSPHERIC CHEMISTRY MODELS REGARDING THE BUDGETS OF O3 AND CH4 AND OTHER PHOTO-OXIDIZED SPECIES. THE PRIMARY DATA SETS USED HERE ARE FROM AIRCRAFT IN SITU MEASUREMENTS THAT GIVE A NEAR-COMPLETE MEASUREMENT OF ATMOSPHERIC COMPOSITION ON A 10-SECOND FLIGHT PATH. AS WE HAVE SHOWN FOR THE ATMOSPHERIC TOMOGRAPHY (ATOM) MISSION SUCH DATA ALLOW US TO CALCULATE THE DAILY BUDGETS OF O3 CH4 AND OTHER PHOTO-OXIDIZED SPECIES SUCH AS CO OR DIMETHYL SULFIDE. WE WILL COMBINE THE ATOM DATA (REPRESENTING THE VAST REMOTE-FROM-POLLUTION ATMOSPHERE) WITH THE KORUS-AQ AND FIREX-AQ DATA (REPRESENTING THE IMMEDIATE POLLUTION-SOURCE ATMOSPHERE) THUS PROVIDING US A VIEW OF THE RANGES IN PHOTOCHEMISTRY. WE PLAN TO DEVELOP METRICS FOR CCMS THAT EXAMINE THE PRODUCTION AND LOSS OF O3 FOLLOWING FROM NEAR SOURCE TO REMOTE TROPOSPHERE AND IDENTIFYING THE SPECIFIC NATURE OF CHEMISTRY THAT DRIVES IT. THE OTHER CRITICAL COMPONENT OF THE O3 BUDGET IS THE STRATOSPHERE TO TROPOSPHERE EXCHANGE (STE) FLUX. WHILE WE CAN EASILY 'SEE' STE FOLDING EVENTS IT IS NIGH IMPOSSIBLE TO INTEGRATE THE NET O3 FLUX WITH ANY DEGREE OF CERTAINTY. INSTEAD OUR STRATEGY USES A MIX OF O3 AND N2O MEASUREMENTS FROM AURA MLS AND OMI SCISAT/ACE AND NOAA SURFACE MEASUREMENTS OF N2O. THESE METRICS ARE EFFECTIVE PROXIES FOR THE ATMOSPHERIC CHEMISTRY AND TRANSPORT PROCESSES RELATED TO STE AND GOOD MODEL PERFORMANCE FOR THESE GIVES CONFIDENCE IN THE MODEL DERIVED O3 FLUX. THIS RESEARCH IS CLEARLY TIED TO SEVERAL OF THE ATMOSPHERIC COMPOSITION FOCUS AREA SCIENCE QUESTIONS: IT DOCUMENTS AND HELPS EXPLAIN CHANGING COMPOSITION IT QUANTIFIES THE STRATOSPHERIC INFLUX OF OZONE AND POSSIBLE SURFACE AIR QUALITY EFFECTS IT BUILDS CONFIDENCE IN MODEL PROJECTIONS OF LIFETIMES AND FLUXES IN THE FUTURE. IN TERMS OF THE ACCDAM CALL IT COMBINES AIRCRAFT DATA SETS IN NEW WAYS AND EXTENDS THEIR USE EVALUATING CHEMISTRY-CLIMATE MODELS. IN TERMS OF THE OVERALL EARTH SCIENCE RESEARCH PROGRAM IT PROVIDES A NEW BASIS FOR EVALUATING NASA CHEMISTRY MODELS AND THE MERRA-2 METEOROLOGICAL FIELDS.