The NASA SMAP Level 4 Carbon (L4_C) Product Suite

John Kimball (U. Montana) and Rolf Reichle

The primary science objectives of the SMAP Level 4 Carbon (L4_C) product are to:

• Determine Net carbon Ecosystem Exchange (NEE) regional patterns and temporal (daily, seasonal, and annual) behavior to within the accuracy range of in situ tower measurements of these processes;

• Link NEE estimates with component carbon fluxes, Gross Primary Productivity (GPP) and ecosystem respiration (RH), and the primary environmental constraints (EC) to ecosystem productivity and respiration.

Fig 1 (left): Overview of the SMAP L4_C product elements.

Fig 2 (right): Gross primary productivity (GPP) from the SMAP L4_C product and independent observations.

L4_C algorithm
Terrestrial Carbon Flux (TCF) model developed at the University of Montana
NASA SMAP L4_SM soil moisture and soil temperature
Surface meteorological data from the NASA GEOS-5 Forward Processing system


Entekhabi, D. et al. 2014. SMAP Handbook–Soil Moisture Active Passive: Mapping Soil Moisture and Freeze/Thaw from Space. Pasadena, CA USA: SMAP Project, JPL CL#14-2285, Jet Propulsion Laboratory.

Glassy, J., J.S. Kimball, L. Jones, R. H., Reichle, R. A. Lucchesi, J. V. Ardizzone, G.-K. Kim, E. B. Smith, and B. H. Weiss, 2015: Soil Moisture Active Passive (SMAP) Mission Level 4 Carbon (L4_C) Product Specification Document. GMAO Office Note No. 11 (Version 1.9), 65 pp, NASA Goddard Space Flight Center, Greenbelt, MD, USA. Available from

Kimball, J. S., L. A. Jones, J. P. Glassy, and R. Reichle. 2014. SMAP Algorithm Theoretical Basis Document, Release A: L4 Carbon Product. SMAP Project, JPL D-66484, Jet Propulsion Laboratory, Pasadena CA. 76 pp., 2.7 MB

Kimball, J. et al. 2015. Soil Moisture Active Passive (SMAP) Project Assessment Report for the Beta-Release L4_C Data Product.

Kimball, J., L. A. Jones, J. P. Glassy, and R. Reichle. 2015. SMAP L4 Global Daily 9 km Carbon Net Ecosystem Exchange. Version 1. [indicate subset used]. Boulder, Colorado USA: NASA National Snow and Ice Data Center Distributed Active Archive Center.

« GMAO Science Snapshots