IN THE NEXT FIVE TO SEVEN YEARS TWO NEW DEVELOPMENTS WILL SIGNIFICANTLY ENHANCE OUR PASSIVE MICROWAVE ATMOSPHERIC REMOTE SENSING CAPABILITIES. FIRSTLY UNDER THE EARTH VENTURE INSTRUMENT-3 PROGRAM NASA HAS JUST FUNDED THE TROPICS(1) MISSION CONSISTING OF 12 CUBESATS WITH PASSIVE MICROWAVE SENSORS ON BOARD. SECONDLY EUMETSAT(2) AS PART OF ITS EPS-SG(3) PROGRAM WILL LAUNCH NEW MICROWAVE AND SUB-MILLIMETER INSTRUMENTS TAGGED MWI(4) AND ICI(5). THE US TROPICS MISSION AND THE EUROPEAN MWI/ICI MISSIONS SHARE SEVERAL TECHNOLOGICAL INNOVATIONS INCLUDING THE USE OF NEW CHANNELS AROUND THE 118 GHZ OXYGEN ABSORPTION LINE AS WELL AS NEW HIGH-FREQUENCY CHANNELS BEYOND 200 GHZ. I AM MEMBER OF NASAS TROPICS SCIENCE TEAM AND WITHIN TROPICS I AM THE LEAD-INVESTIGATOR RESPONSIBLE FOR ALGORITHM DEVELOPMENT. HERE I PROPOSE A USPI EFFORT THAT WOULD ENABLE ME TO WORK CLOSELY WITH EUMETSAT AND THE GERMAN WEATHER SERVICE ON THE FOLLOWING THREE ISSUES RELATED TO TROPICS AND MWI/ICI: 1. PHYSICAL STUDIES ON ICE PARTICLE SCATTERING AFFECTING HIGH-FREQUENCY MICROWAVE AND SUB-MILLIMETER CHANNELS WITH PARTICULAR EMPHASIS ON THE NEW OBSERVATIONAL CAPABILITIES AROUND 118 GHZ AND BEYOND 200 GHZ. WE WILL USE UP-TO-DATE NON-SPHERICAL SCATTERING DATABASES FULL RADIATIVE TRANSFER MODELS AS WELL AS FULL ORBIT AND INSTRUMENT SIMULATORS TO SIMULATE THE EFFECT OF HYDROMETEORS AS ACCURATELY AS POSSIBLE AND TO DEVELOP PROXY DATASETS THAT CAN BE USED FOR PRE-LAUNCH ALGORITHM DEVELOPMENT AND SENSITIVITY STUDIES. 2.INFORMATION CONTENT STUDIES OF THE NEW CHANNEL COMBINATIONS WITH RESPECT TO ICE-PARTICLE SCATTERING AND INTEGRATED CLOUD AND PRECIPITATION PARAMETERS USING FULL OPTIMAL ESTIMATION THEORY BASED ON THE DATASETS DEVELOPED UNDER ITEM 1. THE NEW HIGH-FREQUENCY CHANNELS WILL ALLOW FOR BETTER ESTIMATION OF ICE WATER PATH AND POSSIBLY OTHER CLOUD AND PRECIPITATION PARAMETERS. A SERIES OF INFORMATION CONTENT ANALYSES WILL ALLOW FOR A QUANTIFICATION OF THESE EFFECTS SUPPORT OUR THEORETICAL UNDERSTANDING OF THE NEW SYSTEMS AND DIRECTLY FEED INTO ALGORITHM DEVELOPMENT WORK. 3.DEVELOP RETRIEVAL ALGORITHMS FOR ICE AND LIQUID WATER PATH AND OTHER PRECIPITATION- AND CLOUD-RELATED PRODUCTS. THESE ALGORITHMS WILL EMPLOY OPTIMAL ESTIMATION/ONE-DIMENSIONAL VARIATIONAL DATA ASSIMILATION TECHNIQUES WHICH ARE CURRENTLY ALREADY BEING USED BY THE PI FOR OTHER PROJECTS. HERE WE WILL ADOPT THOSE TECHNIQUES FOR USE WITH THE NEW SENSORS BASED ON THE FINDINGS AND DATASETS UNDER ITEMS 1 AND 2 ABOVE. BOTH NASA AND THE EUROPEAN PROJECT PARTNERS WILL HAVE DIRECT AND SUBSTANTIAL BENEFITS FROM THIS PROJECT. IN PARTICULAR THE PROPOSED WORK WILL HAVE A POSITIVE IMPACT ON NASA S TROPICS MISSION VIA COORDINATION BETWEEN SIMILAR EUROPEAN AND US EFFORTS. BEYOND THESE IMMEDIATE BENEFITS THE PROJECT WILL FURTHER HELP INFORM NASA ON POTENTIAL DIRECTIONS FOR POST-GPM PRECIPITATION MISSIONS SUCH AS THOSE CURRENTLY STUDIED BY THE CAPPM(6) GROUP (SKOFRONICK-JACKSON LEAD BENNARTZ AND OTHERS CO-I). IT WILL ALSO CONTRIBUTE TO ONGOING INTERNATIONALLY COORDINATED EFFORTS SUCH AS THE WCRP(7) /CGMS(8) SCOPE-CM(9) PROGRAM. ACRONYMS 1: TROPICS: TIME-RESOLVED OBSERVATIONS OF PRECIPITATION STRUCTURE AND STORM INTENSITY WITH A CONSTELLATION OF SMALLSATS 2: EUMETSAT: EUROPEAN ORGANISATION FOR THE EXPLOITATION OF METEOROLOGICAL SATELLITES 3: EPS-SG: EUROPEAN POLAR SYSTEM SECOND GENERATION 4: MWI: MICROWAVE IMAGER 5: ICI: ICE CLOUD IMAGER 6: CAPPM: CLOUD AND PRECIPITATION PROCESS MEASUREMENTS GROUP (URL HTTP://PMM.NASA.GOV/CAPPM). 7: WCRP: WORLD CLIMATE RESEARCH PROGRAM 8: CGMS: COORDINATION GROUP FOR METEOROLOGICAL SATELLITES 9: SCOPE-CM: SUSTAINED AND COORDINATED PROCESSING OF ENVIRONMENTAL SATELLITE DATA FOR CLIMATE MONITORING. (URL: HTTP:// WWW.SCOPE-CM.ORG )