MEASUREMENTS OF ICE THICKNESS VELOCITY ELEVATION AND BED TOPOGRAPHY ARE CRITICAL TO OBSERVE AND UNDERSTAND THE EVOLUTION OF COASTAL SECTORS OF THE ICE SHEETS IN GREENLAND AND ANTARCTICA WHICH IN TURN HAVE A MAJOR INFLUENCE ON GLOBAL SEA LEVEL RISE NOW AND IN THE FUTURE. HERE WE WILL PROVIDE SCIENTIFIC GUIDANCE TO NASA'S OPERATION ICEBRIDGE (OIB) MISSION AS SCIENCE TEAM (ST) MEMBER TO STUDY COASTAL ICE DYNAMICS AND ICE SHEET MASS BALANCE IN ANTARCTICA AND GREENLAND BASED ON OUR EXPERIENCE STUDYING CHANGES IN ICE DYNAMICS ICE-OCEAN INTERACTION AND ICE SHEET/ICE SHELF MASS BALANCE USING SATELLITE AIRBORNE AND OTHER DATA. WE WILL ADOPT APPROPRIATE MEASUREMENT STRATEGIES TO BUILD UP TIME SERIES OF LASER ALTIMETRY DATA BRIDGING ICESAT-1 AND ICESAT-2 DOCUMENT VOLUME CHANGES OVER THE PAST DECADES AND PREPARE FOR CAL/VAL ACTIVITIES WITH ICESAT-2. WE WILL GENERATE 2 SETS OF ADVANCED PRODUCTS: 1) ICE THINNING CORRECTIONS FOR ICE DISCHARGE IN GREENLAND; AND 2) ANTARCTIC ICE SHELF BATHYMETRY FROM GRAVITY. FOR (1) WE WILL GENERATE OIB TIME SERIES OF LASER ALTIMETRY ON OUTLET GLACIERS TO QUANTIFY GLACIER THINNING AT FLUX GATES AROUND GREENLAND CORRECT THE DISCHARGE ESTIMATES AND IMPROVE THE PRECISION OF MASS BALANCE ESTIMATES. FOR (2) WE WILL USE A NEW 3-D INVERSION CONSTRAINED BY A MASS CONSERVATION ALGORITHM (MC) INLAND AND MULTIBEAM ECHO SOUNDING (MBES) DATA OFF SHORE TO INFER ICE SHELF BATHYMETRY FOR GETZ ICE SHELF AND GEORGE VI ICE SHELF ANTARCTICA. THE PRODUCTS WILL BE OF HIGH INTEREST TO ICE-OCEAN INTERACTION STUDIES ESPECIALLY IN RELATION TO THE TRANSPORT OF SUBSURFACE OCEAN HEAT TOWARD THE GLACIERS AND THE ESTIMATION OF MELT RATES. IN ADDITION WE WILL COLLABORATE WITH OTHER RESEARCHERS ON 2 ONGOING STUDIES: 1) EVALUATION OF SURFACE MASS BALANCE MODELS (SMB) FROM LASER ALTIMETRY TIME SERIES; AND 2) RECONSTRUCTION OF BED TOPOGRAPHY OR BEDMACHINE FROM DEPTH SOUNDING DATA. FOR (1) WE WILL ANALYZE PRE-OIB/OIB AND SPRING TO FALL CAMPAIGNS IN THE ABLATION ZONE OF GREENLAND TO EVALUATE SMB MODELS (RACMO MAR GEOS5) AND QUANTIFY THEIR ERRORS IN RUNOFF; THIS WILL IMPROVE THE DETERMINATION OF ICE MASS BALANCE AND HELP UNDERSTAND THE LIMITATIONS OF ICESAT-2. FOR (2) WE WILL USE DEPTH RADAR SOUNDING COMBINED WITH INSAR-DERIVED ICE MOTION VECTORS TO IMPROVE BEDMACHINE GREENLAND FILL DATA GAPS AND EXTEND BEDMACHINE ANTARCTICA IN SELECT SECTORS. IN GREENLAND WE WILL COMBINE OIB RESULTS WITH MBES SURVEYS OF THE COASTLINE FROM NASA'S EVS'2 OCEAN MELTING GREENLAND (OMG) MISSION TO PROVIDE SEAMLESS TOPOGRAPHY ACROSS THE ICE FRONT REGIONS. THESE PRODUCTS ARE OF HIGH IMPORTANCE FOR ICE SHEET AND OCEAN MODELING STUDIES. WE WILL PROVIDE CONTINUOUS FEEDBACK TO THE ST AND OIB PROJECT ON THE PRODUCT GENERATION TO GUIDE MISSION PLANNING. AS ST MEMBER WE WILL GUIDE MISSION PLANNING OPTIMIZE THE MEASUREMENT STRATEGY PROVIDE FEEDBACK ON DATA QUALITY CONTRIBUTE TO HIGHER-ORDER PRODUCT GENERATION ENSURE THAT OIB MEETS ITS SCIENCE OBJECTIVES AND HELP ASSEMBLE THE FINAL REPORT OF THE OIB MISSION. LESSONS LEARNED FROM PHASES 1 AND 2 OF OIB WILL HELP IMPROVE THE OBSERVATION STRATEGY QUALITY CONTROL ADVOCACY OF OIB IN THE COMMUNITY AND DATA USAGE AND REPORTING OF THE MISSION PROGRESS TOWARDS ITS STATED SCIENCE GOALS TO MANAGEMENT AND NASA. WE WILL CONTINUE ADVOCACY OF THE OIB MISSION AT THE NATIONAL AND INTERNATIONAL LEVELS PUBLISH SCIENCE RESULTS AND TAKE INTO ACCOUNT FEEDBACK COMMENTS OR REQUESTS FROM THE COMMUNITY WHEN DESIGNING FIELD CAMPAIGNS. A MAJOR GOAL OF PHASE 3 WILL REMAIN TO SUPPORT ICESAT-2 CAL/VAL ACTIVITIES AND WRAP UP THE OIB MISSION. OVERALL OUR EFFORT WILL CONTRIBUTE TO THE SUCCESS OF OIB MISSION THE TIMELY AVAILABILITY OF QUALITY DATA FOR THE SCIENTIFIC COMMUNITY AND THE ASSESSMENT OF OIB CONTRIBUTION TO CRYOSPHERE SCIENCE TOWARD THE END OF THE MISSION. THIS WORK WILL CONTRIBUTE TO NASA'S EARTH SCIENCE STRATEGIC GOALS OF STUDYING THE ROLE OF EARTH'S ICE MASSES ON SEA LEVEL RIS