THIS PROPOSED RESEARCH WILL ANALYZE GROUND-BASED AND AIRBORNE RADAR OBSERVATIONS FROM THE IPHEX AND OLYPEX FIELD CAMPAIGNS INCLUDING NPOL AND D3R; EXRAD HIWRAP (NADIR POINTING) AND CRS ON THE ER-2 AIRCRAFT; AND ARP-3 ON THE DC-8 AIRCRAFT. IN ADDITION SCANNING HIWRAP OBSERVATIONS WHILE ON THE GLOBAL HAWK DURING THE NASA SHOUT HRR FIELD CAMPAIGN WILL BE ANALYZED TO PROVIDE 25 KM CROSS-TRACK 13-/35-GHZ RADAR OBSERVATIONS AT 1X1 KM HORIZONTAL BY 0.1 KM VERTICAL RESOLUTION. TIME-SPACE RAINDROP SIZE DISTRIBUTION (DSD) PARAMETERS WILL BE RETRIEVED FROM EACH HIGH-RESOLUTION RADAR DATA SET WITH SUBSEQUENT LOW-RESOLUTION DPR MEASUREMENTS SIMULATED USING A DPR SIMULATOR DEVELOPED FROM PRIOR NASA SUPPORT. THESE SIMULATED DPR MEASUREMENTS DERIVED FROM GV OBSERVATIONS WILL BE THE FOUNDATION FOR IMPROVED UNDERSTANDING OF SUB-IFOV PRECIPITATION VARIABILITY AND FOR THE DEVELOPMENT OF STATISTICAL RELATIONSHIPS CONSTRAINING NUBF PARAMETERIZATIONS IN RAINFALL RETRIEVAL ALGORITHMS.