THE LARGEST IMPEDIMENTS TO ESTIMATING CLIMATE CHANGE REVOLVE AROUND A LACK OF QUANTITATIVE INFORMATION ON AEROSOL FORCING AND OUR POOR UNDERSTANDING OF AEROSOL-CLOUD PROCESSES AND CLOUD FEEDBACKS IN THE CLIMATE SYSTEM. THE CLIMATE COMMUNITY REQUIRES NEW OBSERVATIONS AND BETTER UNDERSTANDING OF AEROSOL AND CLOUD PROCESSES TO NARROW UNCERTAINTIES ON ESTIMATES OF CLIMATE CHANGE. HERE WEPROPOSE TO FLY IN THE SEAC4RS CAMPAIGN TWO EXCITING NEW INSTRUMENTS FOR THE DETAILED CHARACTERIZATION OF CLOUD AND AEROSOL PARTICLES: THE PACS VNIR POLARIMETER COMBINED WITH A SWIR CLOUD CAMERA ON THE ER2 AIRCRAFT AND THE POLARIZED IMAGING NEPHELOMETER (PI-NEPH) ON THE NASA DC8. THE PI-NEPH IS ALSO PROPOSED TO FLY IN THE NORTH AMERICAN DC3 CAMPAIGN.THE PASSIVE AEROSOL CLOUD SUITE (PACS) MEETS ALL REQUIREMENTS OF THE IMAGING POLARIMETER DESCRIBED BY THE NRC DECADAL SURVEY FOR THE AEROSOLS-CLOUDS-ECOSYSTEMS (ACE) MISSION. HIGHLY CAPABLE SMALL AND VERSATILE PACS IS THE ONLY IMAGING POLARIMETER DESIGNED TO MEET THE NEEDS OF BOTH THE AEROSOL AND CLOUD COMMUNITIES OFFERING NEW INSIGHT INTO THE ATMOSPHERIC PROCESSES THAT INFLUENCE CLIMATECHANGE. PACS PRESENTS THE FIRST EVER OPPORTUNITY TO MEASURE POLARIZED LIGHT REFLECTED FROM THE EARTH WITH WIDE FIELD OF VIEW (FOV) HYPER-ANGULAR CAPABILITY BROAD SPECTRAL RANGE AND WITH HIGH POLARIMETRIC ACCURACY. THE PACS CONCEPT HIGHLIGHTS HIGH ANGULAR DENSITY OF MINIMUM 22 ANGLES IN EACH WAVELENGTH AND HYPERANGLE CAPABILITY OF MORE THAN 60 ANGLES IN A DESIGNATED WAVELENGTH NECESSARY TO RESOLVE VITAL AEROSOL AND CLOUD PROPERTIES.THE PI-NEPH IS AN IN SITU INSTRUMENT DESIGNED TO MEASURE THE FULL PHASE MATRIX OF AEROSOL PARTICLES IN 3 WAVELENGTHS (470 550 AND 670NM) FROM ABOUT 2 TO 178 DEGS SCATTERING ANGLES. THE PI-NEPH WILL PROVIDE NOT ONLY AN INVALUABLE TOOL FOR THE DIRECT VALIDATION OF THE NEXT GENERATIONS OF MULTI-ANGLE POLARIMETERS IN SPACE BUT IT WILL ALSO PROVIDE ACCURATE AND DETAILED CHARACTERIZATION OF THE SCATTERINGPROPERTIES OF STUDIED AEROSOL PARTICLES. WITH THE PI-NEPH DATA WE WILL BE ABLE TO COLLECT A COMPLETE AND UNPRECEDENTED DATA BASE OF MEASUREMENT-BASED AEROSOL SCATTERING PROPERTIES.THE PROPOSED INSTRUMENT-LED MEASUREMENT ACTIVITIES WILL BE BACKED BY SERIOUS ALGORITHM DEVELOPMENT MAKING USE OF INNOVATIONS IN RADIATIVE TRANSFER AND OPTIMIZATION TECHNIQUES TO OBTAIN RETRIEVALS OF AEROSOL OPTICAL AND PHYSICAL PROPERTIES AND PHASE FUNCTIONS AND SIZE DISTRIBUTIONS OF ICE PARTICLE CLOUDS. THE COMBINATION OF NEW TECHNOLOGY AND NEW ALGORITHMS OFFERS BETTER CHARACTERIZATION OF AEROSOL AND CLOUD PROPERTIES BETTER CONSTRAINTS ON HOW THESE PROPERTIES ARE REPRESENTED IN MODELS AND BETTER UNDERSTANDING OF THE AEROSOL AND CLOUD PROCESSES THAT AFFECT CLIMATE.