Submitted to: IEEE IGARSS Annual Proceedings
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/17/2009
Publication Date: 5/15/2009
Publication URL: http://handle.nal.usda.gov/10113/44599
Citation: Entekhabi, D., Njoku, E.G., O'Neill, P.E., Kellogg, K.H., Crow, W.T., Edelstein, W.N., Entin, J.K., Goodman, S.D., Jackson, T.J., Johnson, J., Kimball, J., Peipmeier, J.R., Koster, R.D., McDonald, K.C., Moghaddam, M., Moran, M.S., Reichle, R., Shi, J.C., Spencer, M.W., Thurman, S.W. 2009. The Soil Moisture Active and Passive (SMAP) Mission. Proceedings of the IEEE. 98(5):704-716. Interpretive Summary: The NASA Soil Moisture Active/Passive (SMAP) mission is an exploratory satellite mission that seeks to deploy the first spaceborne sensor optimally designed to globally measure surface soil moisture. Data products from SMAP have the potential to aid a range of climatic and hydrologic applications (e.g. seasonal weather forecasting, drought monitoring, and flood forecasting) relevant to agricultural management issues. This paper provides a basic overview of the mission and includes discussion of mission instrumentation, soil moisture retrieval techniques, and scientific motivation. The mission is currently in development stage and has an expected launch data sometime in 2014. USDA ARS scientists have been involved in the project since its inception and are actively working to develop agricultural applications for SMAP data products.
Technical Abstract: The Soil Moisture Active and Passive (SMAP) Mission is one of the first Earth observation satellites being developed by NASA in response to the National Research Council’s Decadal Survey. SMAP will make global measurements of the moisture present at Earth's land surface and will distinguish frozen from thawed land surfaces. Direct observations of soil moisture and freeze/thaw state from space will allow significantly improved estimates of water, energy and carbon transfers between land and atmosphere. Soil moisture measurements are also of great importance in assessing flooding and monitoring drought. SMAP observations can help mitigate these natural hazards, resulting in potentially great economic and social benefits. SMAP soil moisture and freeze/thaw timing observations will also reduce a major uncertainty in quantifying the global carbon balance by helping to resolve an apparent missing carbon sink on land over the boreal latitudes. The SMAP mission concept would utilize an L-band radar and radiometer. These instruments will share a rotating 6-meter mesh reflector antenna to provide high-resolution and high-accuracy global maps of soil moisture and freeze/thaw state every two to three days. The SMAP instruments provide direct measurements of surface conditions. In addition, the SMAP project will use these observations with advanced modeling and data assimilation to provide deeper root-zone soil moisture and estimates of land surface-atmosphere exchanges of water, energy and carbon. SMAP is scheduled for a 2014 launch date