SULFUR DIOXIDE (SO2) AND NITROGEN DIOXIDE (NO2) ARE TOXIC CRITERIA POLLUTANTS AND ALSO PRECURSORS TO SMOG AND HAZE. VOLCANIC SO2 IS A MAJOR NATURAL FORCING TO THE CLIMATE AND PLAYS AN IMPORTANT ROLE IN THE DEPLETION OF STRATOSPHERIC OZONE. SINCE THE BEGINNING OF THE NASA EOS AURA MISSION OUR TEAM AT GSFC HAS BEEN IN CHARGE OF THE OZONE MONITORING INSTRUMENT (OMI) STANDARD SO2 AND NO2 PRODUCTS TWO EOS CORE DATA RECORDS THAT HAVE BEEN INSTRUMENTAL IN ADVANCING OUR UNDERSTANDING OF GLOBAL AIR POLLUTION. MANY OPERATIONAL USERS ALSO RELY ON OUR PRODUCTS FOR IMPROVED AIR QUALITY FORECASTS AND FOR MITIGATION OF AVIATION HAZARDS CAUSED BY VOLCANIC ERUPTIONS. WITH OMI NOW PROVIDING REDUCED SPATIAL COVERAGE IT IS CRITICAL TO EXTEND THE EOS SO2 AND NO2 RECORDS. THE SNPP/OZONE MAPPING AND PROFILER SUITE (OMPS) IS A PRIMARY CANDIDATE FOR THIS TASK. HOWEVER BUILDING COHERENT RECORDS BETWEEN OMI AND OMPS POSES SIGNIFICANT CHALLENGES AS BOTH SO2 AND NO2 HAVE RELATIVELY WEAK SIGNALS AND THEIR RETRIEVALS ARE SUBJECT TO VARIOUS INTERFERENCES. EVEN A SMALL ARTIFACT IN RETRIEVALS MAY CAUSE A LARGE BIAS BETWEEN THE TWO INSTRUMENTS WHICH ALSO FEATURE DIFFERENT SPATIAL AND SPECTRAL RESOLUTIONS. THE BEST APPROACH TO ACHIEVE MAXIMUM CONTINUITY BETWEEN OMI AND OMPS IS THEREFORE TO USE CONSISTENT ALGORITHMS CAPABLE OF PRODUCING RETRIEVALS WITH SMALL NOISE AND BIAS. WE PROPOSE TO IMPLEMENT OUR MATURE STATE-OF-THE-ART AURA/OMI OPERATIONAL ALGORITHMS WITH SNPP/OMPS TO PRODUCE EOS CONTINUITY SO2 AND NO2 PRODUCTS. OUR OBJECTIVES ARE TO: - PRODUCE SNPP/OMPS ANTHROPOGENIC AND VOLCANIC SO2 DATA PRODUCTS TO EXTEND OUR EOS CORE OMI SO2 DATA RECORDS; - PRODUCE SNPP/OMPS NO2 DATA PRODUCT TO EXTEND OUR EOS CORE OMI NO2 DATA RECORD; - EVALUATE AND VALIDATE OUR SNPP/OMPS PRODUCTS AND PRODUCE VALUE-ADDED HIGHER LEVEL PRODUCTS SUCH AS ESTIMATED EMISSIONS AND LIGHTNING NOX THAT WILL EXTEND OMI RECORDS AND ENABLE SCIENTIFIC ANALYSES. - IMPROVE OUR EXISTING DIRECT READOUT VOLCANIC SO2 AND ASH INDEX ALGORITHMS TO BETTER SUPPORT OPERATIONAL USERS IN AVIATION SAFETY MANAGEMENT. - IMPLEMENT AN ADVANCED VOLCANIC SO2 HEIGHT ALGORITHM ALREADY SUCCESSFULLY TESTED ON GLOBAL OZONE MONITORING EXPERIMENT 2 (GOME-2) WITH SNPP/OMPS. COMPREHENSIVE STUDIES [LI ET AL. 2017; ZHANG ET AL. 2017] HAVE DEMONSTRATED THAT OUR ADVANCED SO2 ALGORITHM CAN PRODUCE HIGHLY CONSISTENT DATA BETWEEN OMI AND OMPS. WE ARE CURRENTLY PRODUCING AN OMPS SO2 RESEARCH PRODUCT AT NASA OZONE SIPS AND OFFER PUBLIC ACCESS TO THE ENTIRE DATASET AT NASA AURA VALIDATION DATA CENTER. IT IS THE FIRST PUBLICLY AVAILABLE OMPS SO2 PRODUCT THAT IS OF SUFFICIENTLY HIGH QUALITY FOR BOTH AIR QUALITY AND VOLCANOLOGY STUDIES. OUR ADVANCED NO2 ALGORITHM IS ALSO CAPABLE OF MAXIMIZING THE CONSISTENCY BETWEEN OMI AND OMPS DESPITE THE LACK OF SPECTRAL COVERAGE BY OMPS AT VISIBLE WAVELENGTHS THAT ARE MORE SENSITIVE TO NO2. OUR PROPOSAL IS RELEVANT TO THE PRESENT NRA IN THAT IT WILL ADDRESS A CRITICAL AND URGENT NEED OF THE COMMUNITY FOR EOS CONTINUITY SO2 AND NO2 DATA RECORDS. OUR PROPOSAL BUILDS ON OUR TEAM'S TRACK RECORD IN DELIVERING HIGH QUALITY OMI PRODUCTS OUR EXPERTISE IN ALGORITHM DEVELOPMENT AND DATA ANALYSIS AND OUR EXPERIENCE WORKING WITH NASA OZONE SIPS AND DIRECT READOUT LABORATORY. OUR PROPOSAL ALSO LEVERAGES OUR CONTINUED EFFORT IN IMPROVING OMI SO2 AND NO2 DATA AS MEMBERS OF THE NASA AURA SCIENCE TEAM. SNPP/OMPS SO2 AND NO2 DATA FROM OUR PROJECT WILL HELP TO BRIDGE THE DATA RECORDS BETWEEN OMI AND THE JPSS-1 OMPS AND THE ESA S5P TROPOSPHERIC MONITORING INSTRUMENT (TROPOMI). WE ARE NASA SELECTED U.S. PARTICIPATING INVESTIGATORS IN TROPOMI AND MEMBERS OF THE ESA S5P VALIDATION TEAM. THIS EFFORT WILL PROVIDE MULTI-DECADE COHERENT GLOBAL OBSERVATIONS THAT WILL HELP TO ADDRESS A KEY SCIENCE QUESTION IN THE ATMOSPHERIC COMPOSITION FOCUS AREA OF NASA EARTH SCIENCE: "HOW IS ATMOSPHERIC COMPOSITION CHANGING?