PASSIVE MICROWAVE SENSORS BECAUSE OF THEIR UNIQUE WAVELENGTHS PROVIDE A WEALTH OF INFORMATION ON EARTH S HYDROLOGIC CYCLE. AT THE SURFACE MICROWAVE RADIATION IS AFFECTED BY SEA SURFACE WIND SPEED AND SEA ICE OVER OCEANS AS WELL AS SOIL MOISTURE AND OVERLYING SNOW OVER LAND. IN THE ATMOSPHERE MICROWAVES INTERACT DIRECTLY WITH WATER VAPOR CLOUDS AND PRECIPITATION. EACH OF THESE INTERACTIONS MAKES IT POSSIBLE TO RETRIEVE THE ASSOCIATED PARAMETER. EACH OF THESE INTERACTIONS HOWEVER ALSO MAKES IT NECESSARY TO ACCOUNT FOR THE OTHER VARIABLES AND THEIR EFFECT ON THE OBSERVED SIGNAL. THE VERY STRENGTH OF THESE WAVELENGTHS THUS ALSO REPRESENTS THEIR ACHILLES HEEL IN THE SENSE THAT CLIMATE TIME SERIES MUST CAREFULLY AVOID CONTAMINATING THE SIGNAL WITH THE VARIABILITY CAUSED BY OTHER PARAMETERS. THIS HAS BEEN THE CHIEF OBJECTIVE OF THE AMSR-E SCIENCE TEAM AND THE SUBSEQUENT AMSR2 SCIENCE TEAM THAT CONSTRUCTED RETRIEVAL ALGORITHM FOR OCEAN SUITE PARAMETERS (WIND SPEED WATER VAPOR AND CLOUD WATER) (DUNCAN ET AL. 2017); PRECIPITATION (KUMMEROW ET AL. 2015) SEA ICE (MARCUS ET AL. 2000 2009) SOIL MOISTURE (BINDLISH ET AL. 2017) AND SNOW WATER EQUIVALENT (TEDESCO AND JEYARATNAM 2016).