THE OBJECTIVE OF THE PROPOSED RESEARCH IS TO CONTINUE THE DEVELOPMENT SUPPORT FOR GPM ALGORITHMS CONDUCT VALIDATION AND SUPPORT ENHANCEMENT. DEVELOP ANALYTICAL TECHNIQUES TO STUDY PRECIPITATION MICROPHYSICAL PARAMETERS SUCH AS HYDROMETEOR AND PRECIPITATION TYPES AT GLOBAL AND REGIONAL SCALES TO DERIVE MICROPHYSICAL INFERENCES OF PRECIPITATION VARIATIONS AT THESE SCALES WITH THE MAIN GOAL OF ALGORITHM MAINTENANCE VALIDATION AND ENHANCEMENT FOR THE PROFILE CLASSIFICATION MODULE AND PRECIPITATION TYPE AND HYDROMETEOR TYPE MODULES FOR DPR. THESE STUDIES WILL BE CONDUCTED USING SPACE-BORNE OBSERVATIONS FROM THE GPM PLATFORM AS WELL AS GROUND DUAL POLARIZATION RADARS AND IN-SITU OBSERVATIONS. ONE OF THE MOST IMPORTANT TASKS OF THE CURRENT PROPOSAL IS TO TEST VERIFY AND FINE-TUNE THE PERFORMANCE OF THE DPR ALGORITHMS FOR THE SCAN PATTERN CHANGE IMPLEMENTED ON THE DPR. THE SPECIFIC TOPICS TO BE ADDRESSED ARE: A) TESTING AND REFINEMENT OF PROFILE CLASSIFICATION ALGORITHMS THAT WILL CLASSIFY THE DUAL-FREQUENCY (KA/KU- BAND) DATA PROFILES ON A GLOBAL SCALE TO REGIONS OF MICROPHYSICAL SIGNIFICANCE AS PART OF THE DPR ALGORITHM MODULE; B) TESTING AND REFINEMENT OF PRECIPITATION TYPE MODULE INCLUDING GROUND SNOWFALL INDEX C) DEVELOP A STRATEGY TO TRANSFER MICROPHYSICAL KNOWLEDGE AND PRECIPITATION ESTIMATES FROM GROUND RADAR TO GPM DUAL-FREQUENCY PRECIPITATION RADAR (DPR); AND D) COLLECT AND ANALYZE THE COORDINATED DATA SETS BETWEEN GPM DPR AND GROUND POLARIMETRIC RADARS THAT ARE PART OF THE CROSS-VALIDATION SYSTEM TO ENSURE TRANSFER OF QUANTITATIVE AND QUALITATIVE MICROPHYSICAL INTERPRETATIONS TO GPM OBSERVATIONS. IN ORDER TO MAKE AN IMPACT ON THE USE OF GPM OBSERVATIONS AND RETRIEVALS THE MICROPHYSICAL INFORMATION MUST BE CORRELATED TO THE SPACE-BORNE OBSERVATIONS. THE SPECIFIC ACTIVITIES IN THAT DIRECTION INCLUDE: A) SIMULATION OF GPM PRECIPITATION RADAR PROFILES FOR CATEGORIES OF MICROPHYSICAL SIGNIFICANCE B) THE DEVELOPMENT OF TECHNIQUES TO GENERATE MAPS OF HYDROMETEOR TYPES SUCH AS SNOW HAIL AND GRAUPEL AND COMPARE THEM AGAINST GROUND DUAL-POLARIZATION RADAR BASED RETRIEVALS C) ENHANCEMENT OF PROFILE CLASSIFICATION MODULE FOR SCAN PATTERN CHANGE AND D) MAKING USE OF THE ADVANCES IN STEPS (A) (B) TO IMPROVE GPM MICROPHYSICAL RETRIEVAL ALGORITHMS. CURRENTLY THE PI PLAYS A KEY ROLE IN THE DPR ALGORITHM DEVELOPMENT GROUP AND IS RESPONSIBLE FOR THE PROFILE CLASSIFICATION MODULE AND HYDROMETEOR TYPE (THAT INCLUDES THE SNOW INDEX MODULE) THAT HAS BEEN RELEASED AND OPERATIONAL. THE MAIN TASK OF THIS PROPOSAL IS TO TEST VALIDATE AND REFINE THE PARAMETERS DURING THE SCAN CHANGE PROCESS IN DPR MAINTAIN PROVIDE SUPPORT CONDUCT VALIDATION AND CONTINUE TO ENHANCE THAT MODULE. THE PI AND THE TEAM PROPOSE TO CONTINUE TO PLAY THAT ROLE AND BE A PART OF THE INTERNATIONAL DPR ALGORITHM TEAM AND IN ADDITION PLAY A SIGNIFICANT ROLE IN THE ANALYSIS OF GROUND RADAR AND OTHER IN-SITU SAMPLING INFRASTRUCTURE FOR THE CROSS-VALIDATION OF HYDROMETEOR CLASSIFICATION AS WELL AS MIXED-PHASE PRECIPITATION STUDIES WITH SPACE-BORNE MEASUREMENTS WITH THE FOCUS ON THE MODULES UNDER DISCUSSION. GPM PRECIPITATION RADAR OBSERVATIONS COMBINED WITH THE KNOWLEDGE OF PRECIPITATION MICROPHYSICS OBSERVED ON THE GROUND WORLDWIDE PROVIDE A SOUND BASIS FOR MODELING THE PRECIPITATION OBSERVATIONS FOR SPACE-BORNE SYSTEMS. WE PROPOSE THE USE OF OBSERVATIONS-BASED SIMULATIONS AS WELL AS GROUND-BASED DUAL POLARIZATION AND DUAL-FREQUENCY RADAR OBSERVATIONS TO DEVELOP DATA-BASED MODELS TO EVALUATE THE SPACE-BORNE DUAL-FREQUENCY RADAR OBSERVATIONS. CONTINUOUS EDUCATIONAL OUTREACH ASSOCIATED WITH THE RESEARCH WILL BE AN INTEGRAL FEATURE OF THIS PROPOSAL.