GROUND CLUTTER NEGATIVELY IMPACTS THE DETECTION AND QUANTIFICATION OF PRECIPITATION FROM BOTH THE TRMM AND GPM RADAR OBSERVATIONS. THIS IS ESPECIALLY TRUE AT HIGH-LATITUDES IN THE COLD SEASON WHEN THE FREEZING LEVEL IS FREQUENTLY CLOSE TO THE GROUND RESULTING IN SIGNIFICANT UNDERESTIMATION OF LIQUID PRECIPITATION. THE GROUND CLUTTER IS A FUNCTION OF THE RADAR INCIDENCE ANGLE IT IS A MINIMUM AT NADIR AND DRASTICALLY INCREASES WITH THE VIEWING ANGLE. FROM AN INSTANTANEOUS AND CLIMATOLOGICAL PERSPECTIVE IT IS NECESSARY TO ACCURATELY ESTIMATE PRECIPITATION AT ALL RADAR VIEWING ANGLES. WE THEREFORE PROPOSE A METHODOLOGY TO MITIGATE GROUND CLUTTER ISSUES USING A COMPREHENSIVE DATABASE OF GPM NEAR-NADIR RADAR OBSERVATIONS MINIMALLY CONTAMINATED BY GROUND CLUTTER MATCHED WITH COINCIDENT GMI OBSERVATIONS. FOR A GIVEN OFF-NADIR RADAR REFLECTIVITY PROFILE THE DATABASE WILL BE USED TO IDENTIFY RECORDS CHARACTERIZED BY SIMILAR SURFACE CONDITIONS FREEZING LEVEL AND REFLECTIVITIES ABOVE THE CLUTTER TO RECONSTRUCT THE INFORMATION OBSCURED BY THE GROUND CLUTTER IN THE OFF-NADIR PROFILE. TO IMPROVE THE COMBINED PRECIPITATION ESTIMATES IN SITUATIONS WHEN THE PRECIPITATION IS TO LIGHT OR SHALLOW TO BE DETECTED BY THE SPACE RADAR WE PROPOSE THE DEVELOPMENT OF A STATISTICAL METHODOLOGY TRAINED USING COINCIDENT GMI - CLOUDSAT PROFILING RADAR (CPR) OBSERVATIONS TO ESTIMATE THE SURFACE PRECIPITATION FROM RADIOMETER-ONLY OBSERVATIONS. SPECIFICALLY WE PROPOSE THE APPLICATION OF A WELL CALIBRATED W-BAND RADAR PROFILING ALGORITHM TO CLOUDSAT CPR OBSERVATIONS COINCIDENT WITH GMI OBSERVATIONS AND THE USE OF CPR PRECIPITATION ESTIMATES AND ASSOCIATED GMI OBSERVATIONS IN THE DEVELOPMENT OF A PROCEDURE TO ESTIMATE SURFACE PRECIPITATION FROM RADIOMETER-ONLY OBSERVATIONS. THE PROCEDURE WILL BE BASED ON A DECISION TREE REGRESSION AND WILL BE DEPLOYED IN THE COMBINED ALGORITHM TO IMPROVE ITS DETECTION AND LIGHT PRECIPITATION ESTIMATION CAPABILITIES. ON MAY 21ST 2018 THE DPR TRANSITIONED TO A NEW SCANNING PATTERN THAT ENABLES THE COLLECTION OF KA-BAND OBSERVATIONS ACROSS THE ENTIRE NORMAL SCAN (NS). THIS IS ACHIEVED BY COLLECTING THE HIGH SENSITIVITY (HS) OBSERVATIONS OUTSIDE THE MATCHED SCAN (MS). THE HS OBSERVATIONS WILL BECOME AVAILABLE AFTER REVIEW BY THE JAPAN AEROSPACE EXPLORATION AGENCY (JAXA). WE PROPOSE THE DEVELOPMENT AND APPLICATION OF A METHODOLOGY THAT ALLOWS FOR THE DERIVATION OF CONSISTENT COMBINED PRECIPITATION ESTIMATES ACROSS THE NS SCAN. THE METHODOLOGY IS AIMED AT MITIGATING THE IMPACT OF THE DEGRADATION OF VERTICAL RESOLUTION WITH THE INCIDENCE ANGLE AND THE GROUND CLUTTER ON THE PRECIPITATION ESTIMATES. THE DEGRADATION OF VERTICAL RESOLUTION AND THE GROUND CLUTTER ARE NOT A SIGNIFICANT PROBLEM IN THE MS SCAN BUT CAN LEAD TO BIASED ESTIMATES IN THE HS SCAN IF NOT PROPERLY ADDRESSED. TO ADDRESS THESE ISSUES WE PROPOSE TWO STATISTICAL CORRECTION PROCEDURES AND A OPTIMAL QUANTIFICATION OF UNCERTAINTIES THROUGH AN EXPECTATION-MAXIMIZATION APPROACH. IN SUMMARY TO FURTHER ENHANCE THE PERFORMANCE OF THE UNIFIED TRMM/GPM COMBINED ALGORITHM WE PROPOSE: 1) THE IMPLEMENTATION AND EVALUATION OF VERTICAL PROFILE OF REFLECTIVITY (VPR) METHODOLOGY THAT ENABLES THE EXTRAPOLATION OF OBSERVED PR/DPR REFLECTIVITY INTO THE CLUTTER REGION; 2) THE DEVELOPMENT FROM COINCIDENT GMI RADIOMETER AND CLOUDSAT RADAR OBSERVATIONS OF A RADIOMETER-ONLY ALGORITHM TO ESTIMATE PRECIPITATION TOO LIGHT (OR SHALLOW) TO BE DETECTED BY THE TRMM PR AND THE GPM DPR; 3) THE DEVELOPMENT OF A METHODOLOGY TO MITIGATE THE DEGRADATION OF THE RADAR VERTICAL RESOLUTION WITH THE INCIDENCE ANGLE AND ITS INTEGRATION WITH THE PROPOSED VPR METHODOLOGY TO ENSURE THE CONSISTENCY COMBINED PRECIPITATION ESTIMATES ACROSS THE NS SCAN. 4) THE VALIDATION OF THE IMPROVED PRECIPITATION ESTIMATES AGAINST SURFACE OBSERVATIONS.