STARTING WITH TOPEX-POSEIDON IN 1992 AND CONTINUING WITH THE JASON SERIES (1-3) OF SATELLITE ALTIMETERS NASA AND ITS PARTNERS HAVE CREATED A CONTINUOUS INTER-CALIBRATED CLIMATE RECORD OF SEA LEVEL. THIS RECORD IS UNIQUE AMONG CLIMATE VARIABLES BECAUSE EACH SUBSEQUENT ALTIMETER WAS LAUNCHED INTO THE SAME ORBIT AS ITS PREDECESSOR AND INTER-CALIBRATED TO PROVIDE SEAMLESS TRANSITION BETWEEN MISSIONS. JASON-3 THE CURRENTLY OPERATING REFERENCE ALTIMETER USES A PULSE-LIMITED POSEIDON ALTIMETER THAT HAS A LONG HERITAGE ON THE JASON-1 AND JASON-2 MISSIONS. BUT ITS SUCCESSOR JASON-CS/SENTINEL-6 WILL IN 2020 TRANSITION TO A SYNTHETIC APERTURE RADAR (SAR) ALTIMETER INSTRUMENT DESIGN AND IT IS IMPERATIVE THAT THIS CHANGE IN THE REFERENCE ALTIMETER INSTRUMENT WILL NOT POSE RISKS TO THE CONTINUITY AND HIGH QUALITY OF THE SEA LEVEL CLIMATE RECORD. THIS PROPOSED WORK AIMS TO EXPLOIT THE NEXT THREE YEARS TO CONDUCT A DETAILED STUDY ON CORE ISSUES RELATING TO SAR ALTIMETRY IN AN EFFORT TO MAINTAIN SEA LEVEL CLIMATE RECORD CONTINUITY FOR THE UPCOMING JASON-CS MISSION. THE STUDY WOULD BE CARRIED OUT USING CURRENT SAR MODE DATA ACQUIRED BY THE CS-2 AND S3-A MISSIONS AS WELL AS ALTIMETRY CAL/VAL MEASUREMENTS CONDUCTED AT THE HARVEST PLATFORM. WIND AND WAVE INFORMATION FROM WAVEWATCH3 (WW3) OUTPUT AND THE COASTAL DATA INFORMATION PROGRAM (CDIP) WILL COMPLEMENT THESE DATA. COASTAL PROCESSING STRATEGIES ALSO WILL BE TESTED ON S3-A/B DATA. BY THE END OF THIS THREE-YEAR STUDY THE PROJECT WILL DELIVER A JASON-CS SAR MODE ALTIMETER SIMULATOR FOR TESTING VARIOUS MISSION CHARACTERISTICS AND SURFACE CONDITIONS/PROPERTIES REFINEMENTS TO THE ALTIMETER SSB MODEL FOR SAR MODE CORRECTIONS FOR ACROSS-TRACK MISPOINTING AND SWELL/WAVE EFFECTS A PROCESSING STRATEGY FOR COASTAL SAR MODE ALTIMETRY AND A U.S. COASTAL ALTIMETRY PRODUCT USING S3-A/B IN PREPARATION FOR JASON-CS