Investigating Greenland and Antarctic Ice Dynamics using Long-term Elevation Change Record: A Proposal for IceBridge Science Team Membership

ICE-SHEET ELEVATION CHANGES ARE SENSITIVE INDICATORS OF ICE-SHEET MASS BALANCE CHANGES AND PROVIDE INVALUABLE INSIGHT INTO SURFACE PROCESSES AND CHANGING ICE DYNAMICS. NASA'S ICEBRIDGE MISSION IS DEDICATED TO COLLECTING AIRBORNE LASER ALTIMETRY DATA TO BRIDGE THE ICESAT AND ICESAT-2 SATELLITE LASER ALTIMETRY MISSIONS. OTHER CRITICAL OBSERVATIONS CHARACTERIZING ICE SHEET SURFACE PROCESSES ICE THICKNESS INTERNAL STRUCTURE AS WELL AS SUBGLACIAL GEOLOGY ARE ALSO ACQUIRED BY THE MISSION. QUANTIFYING ICE SHEET THICKNESS CHANGES IMPERATIVE FOR IMPROVING ICE SHEET MODELS AND SEA LEVEL PREDICTIONS REMAIN A CHALLENGING PROBLEM. TO ADDRESS THIS ISSUE WE HAVE DEVELOPED THE SURFACE ELEVATION RECONSTRUCTION AND CHANGE DETECTION (SERAC) APPROACH.SERAC WAS INITIALLY LIMITED TO ICESAT LASER ALTIMETRY DATA. LATER ON WE EXTENDED SERAC TO INCLUDE AIRBORNE LASER ALTIMETRY OBSERVATIONS AND DEMS DERIVED FROM REPEAT STEREOSCOPIC IMAGERY. THE SERAC METHOD IS RAPIDLY GAINING POPULARITY FOR GLACIOLOGICAL CHANGE DETECTION. IT IS ALSO THE PRIMARY MOTIVATOR FOR SIMILAR CHANGE DETECTION APPROACHES FOR THE UPCOMING ICESAT-2 MISSION. WE HAVE EXTENSIVELY USED SERAC TO STUDY CHANGES OF THE GREENLAND AND ANTARCTIC ICE SHEET AT SCALES FROM INDIVIDUAL OUTLET GLACIERS TO THE ENTIRE ICE SHEET.I PROPOSE TO USE SURFACE ELEVATION RECONSTRUCTION AND CHANGE (SERAC) DETECTION APPROACH TO DEVELOP MULTI-DECADAL TIME SERIES OF ELEVATION AND MASS BALANCE CHANGES OF THE GREENLAND AND ANTARCTIC ICE SHEETS (GRIS AND AIS) BY COMBINING HISTORICAL LASER ALTIMETRY DATA SETS WITH ICEBRIDGE LASER ALTIMETRY OBSERVATIONS AND CRYOSAT-2 RADAR ALTIMETRY DATA. I ALSO PROPOSE TO EXTEND THE CAPABILITIESOF SERAC TO INCORPORATE ICESAT-2 PHOTON COUNTING LASER ALTIMETRY DATA AND TO AUTOMATICALLY DETECT SURFACE PATCHES FOR TIME SERIES EXTRACTION.THE PROPOSED RESEARCH WILL GENERATE ANNUALLY UPDATED LONG-TERM ICE SHEET ELEVATION THICKNESS AND MASS BALANCE TIME SERIES FROM LASER AND RADAR ALTIMETRY DATA TO BRIDGE NASAS ICESAT AND ICESAT-2 MISSIONS. IT WILL ASSIST FLIGHT PLANNING DURING THE LAST AND FINAL STAGE OF THE ICEBRIDGE MISSION AND PROVIDE ACCURATE RECONSTRUCTION OF ICE SHEET ELEVATION THICKNESS AND MASS BALANCE CHANGES AT SCALESFROM INDIVIDUAL OUTLET GLACIERS TO ENTIRE ICE SHEETS. BY INCORPORATING ICESAT-2 OBSERVATIONS INTO THE ELEVATION CHANGE TIME SERIES IT WILL ENABLE THE ESTIMATION OF ICE SHEET ELEVATION CHANGES AT AN EARLY STAGE OF THE ICESAT-2 MISSION AND WILL ASSIST THE CALIBRATION AND VALIDATION OF ICESAT-2 MEASUREMENTS. FINALLY BY REVEALING THE COMPLEXITY OF ICE SHEET CHANGES THE RESULTS WILL SERVE AS A GUIDE FORFUTURE MODELING EFFORTS AND PROVIDE A CRITICALLY NEEDED COMPREHENSIVE ELEVATION DATA SET FOR IMPROVING ICE SHEET BALANCE PROJECTIONS THROUGH DATA ASSIMILATION.