SUBCANOPY AND SUBSURFACE SOIL MOISTURE MEASUREMENTS ON LOCAL REGIONAL AND GLOBAL SCALES CONTRIBUTE TO MANY AREAS OF HUMAN INTEREST SUCH AS WEATHER AND CLIMATE FORECASTING FLOOD PREDICTION DROUGHT ANALYSIS CROP PRODUCTIVITY EVALUATION AND HUMAN HEALTH. ACCURATE ELECTROMAGNETIC CHARACTERIZATION OF THE ORGANIC HORIZON (IN CONJUNCTION WITH BELOW-GROUND BIOMASS) IS A NECESSARY STEP FOR ACCURATE SOIL MOISTURE RETRIEVAL WITHIN LAND COVERED BY HIGH ORGANIC MATTER CONTENT AS WELL AS FOR RETRIEVAL OF PERMAFROST ACTIVE LAYER PROPERTIES WITH ACTIVE OR PASSIVE REMOTE SENSING TECHNIQUES IN THE BOREAL AND ARCTIC REGIONS. IN THIS PROPOSED RESEARCH WE PRESENT A NEW DIELECTRIC MODEL FOR ORGANIC SOIL AT L-BAND AND P-BAND FOR VARIOUS AMOUNTS OF SOIL ORGANIC MATTER AND SOIL TEXTURE. THE INTEREST IN DEVELOPING ORGANIC SOIL DIELECTRIC MODEL STEMS FROM THE OBSERVATION THAT EXISTING MODELS HAVE A LIMITED VALIDITY RANGE AS FAR AS ORGANIC MATTER AND VOLUMETRIC SOIL MOISTURE ARE CONCERNED WHILE A LARGE PORTION OF BOREAL AND ARCTIC REGIONS ARE COVERED WITH ORGANIC SOIL. SUCH A MODEL CAN ENHANCE PREVIOUS SOIL MOISTURE PRODUCTS SUCH AS THOSE FROM SOIL MOISTURE ACTIVE PASSIVE (SMAP) AND SOIL MOISTURE AND OCEAN SALINITY (SMOS) OVER FORESTED LAND AND WILL ALSO IMPROVE PERMAFROST ACTIVE LAYER THICKNESS RETRIEVALS FROM RADAR DATA COLLECTED DURING THE ARCTIC BOREAL VULNERABILITY EXPERIMENT (ABOVE) AIRBORNE CAMPAIGN. IN THIS PROPOSAL WE SEEK TO DEVELOP A NOVEL DIELECTRIC MODEL FOR ORGANIC SOIL THAT WILL ENABLE TRANSLATING RETRIEVED DIELECTRIC CONSTANT FROM RADAR REMOTE SENSING TO SOIL MOISTURE PRODUCTS. TAKING ADVANTAGE OF A LABORATORY-BASED MULTI-STATIC MICROWAVE IMAGING SYSTEM WILL PROVIDE A COMPLETE CHARACTERIZATION OF ORGANIC SOIL DIELECTRIC CONSTANT WHICH CAN THEN BE TRANSLATED TO THE SOIL MOISTURE PROFILE. FOR ACQUIRING A DIELECTRIC MODEL FOR ORGANIC SOIL WE WILL INVESTIGATE THE EFFECT OF ORGANIC MATTER CONTENT AND SOIL SPECIFIC SURFACE AREA (SSA) ON THE DIELECTRIC CONSTANT FOR DIFFERENT ORGANIC SOILS WITH DIFFERENT AMOUNTS OF WATER FROM SATURATION RANGE TO DRY REGIME. THIS INVESTIGATION ON SPECIFIC SURFACE AREA WILL ENABLE US TO PROVIDE A NEW DIELECTRIC MODEL FOR ALL TYPES OF ORGANIC SOIL WITH MINIMUM COMPLEXITY WHICH IS CRUCIAL FOR MICROWAVE REMOTE SENSING APPLICATIONS. THIS PROPOSAL DIRECTLY RESPONDS TO EARTH SCIENCE RESEARCH PROGRAM'S SEEKING TO "IMPROVE THE ABILITY TO PREDICT CHANGES BY BETTER UNDERSTANDING THE ROLES AND INTERACTIONS OF THE OCEAN ATMOSPHERE LAND AND ICE IN THE CLIMATE SYSTEM." THE CONTRIBUTIONS OF THIS 3- YEAR RESEARCH PROJECT ARE 1) DESIGN OF A MULTI-STATIC P- AND L-BAND DUAL-FREQUENCY CAVITY IMAGING SYSTEM MODELED WITH APPROPRIATE FORWARD AND INVERSE ELECTROMAGNETIC METHODS THAT TAKE INTO ACCOUNT ORGANIC LAYERS OF SOIL; 2) DEVELOPMENT OF A DIELECTRIC MODEL BY INVESTIGATING THE RELATIONSHIP BETWEEN ORGANIC MATTER CONTENT SOIL SPECIFIC SURFACE AREA (SSA) VOLUMETRIC WATER CONTENT (VWC) AND THE RECONSTRUCTED DIELECTRIC CONSTANT FOR DIFFERENT TYPES OF SOIL COLLECTED THROUGH A PLANNED FIELD CAMPAIGN IN ALASKA; AND 3) VALIDATION OF THE DEVELOPED ORGANIC SOIL DIELECTRIC MODEL AND ASSESSMENT OF THE ESTIMATION ACCURACY OF THE RETRIEVED PERMAFROST PROPERTIES WITH THE NEW DIELECTRIC MODEL USING RADAR DATA FROM ABOVE AIRBORNE CAMPAIGN.