The NASA Soil Moisture Active Passive (SMAP) mission

Project Summary:

The Soil Moisture Active Passive (SMAP) mission is a first-tier NASA Decadal Survey mission successfully launched in January 2015. The SMAP satellite consists of L-band radar and radiometer sensors designed for global mapping and monitoring of soil moisture and landscape freeze/thaw dynamics. Primary science objectives for the mission include: improving understanding of processes linking terrestrial water, energy and carbon cycles; quantifying the net carbon flux in boreal ecosystems and reducing uncertainties regarding the purported missing carbon sink on land. NTSG is partnering with NASA to produce global operational land products and science applications for SMAP that address mission water and carbon science objectives. These products include SMAP Level 3 retrievals of daily landscape freeze-thaw status and a model enhanced Level 4 Carbon (L4C) product. The SMAP L4C product provides consistent global daily estimates of the terrestrial carbon budget with refined accuracy and performance suitable for global change assessment and monitoring. The L4C product is publicly distributed and includes daily quantification of net ecosystem carbon (CO2) exchange, vegetation photosynthesis (GPP) and ecosystem respiration, surface soil organic carbon and underlying environmental controls on these processes, including soil moisture and frozen temperature constraints.


SMAP L4C Project Set
Zonal Averages
Satellite Image


Entekhabi, D., S. Yueh, P. O’Neill, K. Kellogg et al., SMAP Handbook, JPL Publication, JPL 400-1567, Jet Propulsion Laboratory, Pasadena, California, 182 pages, 2014 (pdf link).

Kimball, J.S., L. A. Jones, J. Glassy, E. N. Stavros, N. Madani, R. H. Reichle, T. Jackson, and A. Colliander, 2016. Soil Moisture Active Passive Mission L4_C Data Product Assessment (Version 2 Validated Release). GMAO Office Note No. 13 (Version 1.0), (pdf link).

Jones, L.A., J.S. Kimball, R.H. Reichle, et al., 2017. The SMAP Level 4 Carbon product for monitoring ecosystem land-atmosphere CO2 exchange. IEEE TGARS (In-press).

Madani, N., J.S. Kimball, L.A. Jones, N.C. Parazoo, and K. Guan, 2017. Global analysis of bioclimatic controls on ecosystem productivity using satellite observations of solar-induced chlorophyll fluorescence. Remote Sensing 9, 530.

Yi, Y., J.S. Kimball, M.A. Rawlins, M. Moghaddam, and E.S. Euskirchen, 2015. The role of snow cover and soil freeze/thaw cycles affecting boreal-arctic soil carbon dynamics. Biogeosciences 12, 5811-5829.

Yi, Y., J.S. Kimball, and R.H. Reichle, 2014. Spring hydrology determines summer net carbon uptake in northern ecosystems. Environmental Research Letters 9, 064003.

Yi, Y., J.S. Kimball, L.A. Jones, R.H. Reichle, R. Nemani, and H.A. Margolis, 2013. Recent climate and fire disturbance impacts on boreal and arctic ecosystem productivity estimated using a satellite-based terrestrial carbon flux model. JGR Biogeosci. 118, 1-17.

Yi, Y., J.S. Kimball, L.A. Jones, R.H. Reichle and K.C. McDonald, 2011. Evaluation of MERRA land surface estimates in preparation for the Soil Moisture Active Passive Mission. Journal of Climate 24(15), 3797-3816.

Key Datasets: 

SMAP Data access page at NSIDC

SMAP L4C data at NSIDC

Project Links: 

SMAP mission science team

See L4C time series for individual sites on the ORNL Soil Moisture Visualizer

NTSG Personnel: