THE PROPOSAL CONTINUES EXISTING PRODUCTIVE COLLABORATIONS BETWEEN UMD AND GSFC ON DEVELOPING PRECISE AND ACCURATE APPROACHES TO PROCESSING HIGH-ALTITUDE AIRBORNE LASER ALTIMETRY. NASA'S LAND VEGETATION AND ICE SENSOR (LVIS) IS AN AIRBORNE LIDAR FACILITY COLLECTING SURFACE TOPOGRAPHY AND STRUCTURE MEASUREMENTS FOR INVESTIGATORS AND MISSIONS. THE LVIS-FACILITY IS THE DIRECT RESULT OF A MULTI-DECADE COLLABORATION BETWEEN NASA AND UMD. APPROX. 200 FLIGHT HOURS OF DATA WERE COLLECTED IN 2017 USING THE SYSTEM A LEVEL OF ACTIVITY EXPECTED TO INCREASE OVER THE NEXT SEVERAL YEARS. WE WILL SUPPORT THE FACILITY BY: 1) ENHANCING AND VALIDATING CURRENT LASER ALTIMETRY CALIBRATION AND VALIDATION APPROACHES SPECIFICALLY FOR THE LVIS SENSOR UNDER TYPICAL FLIGHT OPERATIONS EXPERIENCED BY THE SENSOR USING THE RECENTLY COLLECTED DATA AS A GUIDE; 2) SUPPORT FUTURE FLIGHT MISSIONS AS NEEDED (SCIENCE DATA PROCESSING). 3) BY ASSESSING SURFACE MASS BALANCE AND DYNAMICS BY COMBINING LASER ALTIMETRY WITH OTHER SENSOR AND SURFACE MODELING RESULTS PROVIDE INFORMATION ON THE SUITABILITY FOR VARIOUS LOCATIONS FOR SHORT AND/OR LONG TERM CALIBRATION/VALIDATION TARGETS FOR SPACEBORNE AND AIRBORNE SENSORS INCLUDING GEDI AND ICESAT-II AS WELL AS A BETTER UNDERSTANDING OF MECHANISMS CONTROLLING ICE DYNAMICS.