OF ALL THE REGIONS ON EARTH THE SOUTHERN OCEAN HAS PRESENTED THE GREATEST CHALLENGES OF CONSTRAINING THE PRECIPITATION PHASE RATES AND OCCURRENCE FREQUENCIES. NOT ONLY IS THIS REGION REMOTE WITH LITTLE TO NO RELIABLE VALIDATION MEASUREMENTS BUT GIVEN ITS REMOTENESS FROM CONTINENTAL AND ANTHROPOGENIC INFLUENCES THIS REGION IS UNIQUE IN MANY OTHER ASPECTS INCLUDING THE METEOROLOGY AND THE AEROSOL BACKGROUND. THE LEADING PRECIPITATION CLIMATOLOGIES SHOW NO CONSENSUS IN REMOTELY SENSED PRECIPITATION RATES AMOUNTS OR PHASE ON ZONAL AVERAGES. IN THIS PROPOSAL WE SEEK FUNDING TO ANALYZE A UNIQUE DATA SET COLLECTED FROM THE AUSTRALIAN RESEARCH VESSEL INVESTIGATOR DURING FOUR VOYAGES INTO THE SOUTHERN OCEAN IN 2016 AND 2018. THE MEASUREMENTS COLLECTED DURING THESE VOYAGES INCLUDE VERTICALLY POINTING ACTIVE AND PASSIVE REMOTE SENSING (W-BAND AND K-BAND RADARS 355NM RAMAN LIDAR AND MICROWAVE RADIOMETERS) IN-SITU DISDROMETER AS WELL AS SCANNING FULLY POLARIZED DOPPLER C-BAND RADAR (DURING THE 2018 VOYAGES). THESE VOYAGES TOOK PLACE PRIMARILY IN THE REGION BETWEEN THE TASMAN SEA AND THE EAST ANTARCTIC SHELF WITH THE 2018 VOYAGE SPENDING CONSIDERABLE TIME IN THE -60 REGION WHERE GPM AND FREQUENT STORMS CONVERGED TO PRODUCE AN IN SITU DATA SET THAT HAS THE POTENTIAL TO SIGNIFICANTLY ILLUMINATE THE DISCREPANCIES IN SOUTHERN OCEAN PRECIPITATION RETRIEVED BY ALGORITHMS APPLIED TO NASA SATELLITE MEASUREMENTS. WE THEREFORE PROPOSE TO ADDRESS 4 SPECIFIC OBJECTIVES AS FOLLOWS: A) USE SHIP-BASED DUAL-POLARIZATION SCANNING C-BAND RADAR MEASUREMENTS TO CHARACTERIZE THE PROPERTIES OF PRECIPITATING CLOUD SYSTEMS IN THE LATITUDE BAND FROM -45 TO -65 . B) USE IN SITU-COLLECTED DISDROMETER INFORMATION COLLECTED OVER APPROXIMATELY 10 MONTHS OF UNDERWAY TIME IN THE SOUTHERN OCEAN TO STATISTICALLY DESCRIBE THE FUNCTIONAL CHARACTERISTICS OF PRECIPITATION SIZE DISTRIBUTIONS (PSDS) IN THE SOUTHERN OCEAN PAYING CAREFUL ATTENTION TO CONVECTIVE STRATIFORM TYPES OF BOTH SOLID AND LIQUID PHASES. C) USE A COMBINATION OF SHIP BASED W-BAND AND K-BAND VERTICALLY POINTING RADAR AND PASSIVE MICROWAVE RADIOMETER MEASUREMENTS TO CHARACTERIZE THE CLOUD TO PRECIPITATION PROCESSES AND ICE MICROPHYSICAL PROPERTIES. D) USE THE RESULTS OF A B AND C TO 1) COMPARE DIRECTLY WITH GPM MEASUREMENTS AND RETRIEVAL PRODUCTS FROM SPECIFIC OVERPASSES OF THE GPM SATELLITE OF THE SHIP 2) TO COMPARE STATISTICAL DISTRIBUTIONS OF CLOUD AND PRECIPITATION PROPERTIES (RAIN AND SNOW RATES PHASE PARTITIONING PSD PROPERTIES ETC.) DERIVED FROM THE SHIP-BASED DATA TO SIMILAR QUANTITIES OBSERVED BY AND RETRIEVED FROM GPM DATA IN THE GEOGRAPHICAL DOMAIN AND TIME PERIODS OF THE SURFACE-BASED MEASUREMENTS.