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Title: Assessment of the SMAP level 2 passive soil moisture product

item CHAN, S. - Jet Propulsion Laboratory
item BINDLISH, R. - Science Systems, Inc
item O'NEILL, PEGGY, E. - National Aeronautics And Space Administration (NASA)
item NJOKU, ENI - Jet Propulsion Laboratory
item Jackson, Thomas
item COLLIANDER, ANDREAS - Jet Propulsion Laboratory
item CHEN, FAN - Science Systems, Inc
item BURGIN, M. - Jet Propulsion Laboratory
item DUNBAR, R.S. - Jet Propulsion Laboratory
item PEIPMEIER, J. - National Aeronautics And Space Administration (NASA)
item YUEH, S. - Jet Propulsion Laboratory
item ENTEKHABI, DARA - Collaborator
item Cosh, Michael
item CALDWELL, TODD - University Of Texas
item WALKER, JEFF - Monash University
item WU, X - Monash University
item BERG, A. - University Of Guelph
item ROWLANDSON, T. - University Of Guelph
item PACHECO, A. - Agriculture And Agri-Food Canada
item MCNAIRN, H. - Agriculture And Agri-Food Canada
item THIBEAULT, M. - Collaborator
item MARTINEZ-FERNANDEZ, J. - University Of Salamanca
item GONZALEZ-ZAMORA, A. - University Of Salamanca
item Seyfried, Mark
item Bosch, David - Dave
item Starks, Patrick - Pat
item Goodrich, David - Dave
item Prueger, John
item PALECKI, M. - National Oceanic & Atmospheric Administration (NOAA)
item SMALL, E.E. - University Of Colorado
item ZREDA, M. - University Of Arizona
item CALVET, J.C. - Ecole Nationale
item Crow, Wade
item KERR, Y. - Center For The Study Of The Biosphère From Space(CESBIO)

Submitted to: IEEE Transactions on Geoscience and Remote Sensing
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/1/2016
Publication Date: 5/25/2016
Citation: Chan, S., Bindlish, R., O'Neill, P., Njoku, E., Jackson, T.J., Colliander, A., Chen, F., Burgin, M., Dunbar, R., Peipmeier, J., Yueh, S., Entekhabi, D., Cosh, M.H., Caldwell, T., Walker, J., Wu, X., Berg, A., Rowlandson, T., Pacheco, A., McNairn, H., Thibeault, M., Martinez-Fernandez, J., Gonzalez-Zamora, A., Seyfried, M.S., Bosch, D.D., Starks, P.J., Goodrich, D.C., Prueger, J.H., Palecki, M., Small, E., Zreda, M., Calvet, J., Crow, W.T., Kerr, Y. 2016. Assessment of the SMAP level 2 passive soil moisture product. IEEE Transactions on Geoscience and Remote Sensing. 54(8):1-14. doi:10.1109/TGRS.2016.2561938.

Interpretive Summary: The first assessment of the Soil Moisture Active Passive (SMAP) satellite products based on the radiometer instrument showed that the retrievals are exceeding the mission goal of 0.04 m3/m3. Assessment methodologies utilized include comparisons of SMAP soil moisture retrievals with in situ soil moisture observations from core validation sites and sparse networks and inter-comparison with products from Soil Moisture Ocean Salinity (SMOS) satellite. Three alternative algorithms were considered and the results supported the recommendation to use the Single Channel Algorithm-Vertical Polarization as the baseline. SMAP has been providing products routinely since April, 2015. These results support the reliability of these products for use in agricultural hydrology, weather, and climate applications.

Technical Abstract: The NASA Soil Moisture Active Passive (SMAP) satellite mission was launched on Jan 31, 2015. The observatory was developed to provide global mapping of high-resolution soil moisture and freeze-thaw state every 2–3 days using an L-band (active) radar and an L-band (passive) radiometer. SMAP provides three geophysical (level 2) soil moisture products: a radiometer-only product (L2_SM_P), a radar-only product (L2_SM_A), and a combined radar/radiometer product (L2_SM_AP). The SMAP radiometer-only soil moisture product (L2_SM_P) provides soil moisture estimates posted on a 36 km Earth-fixed grid produced using brightness temperature observations from descending passes. The L2_SM_P product was assessed to have attained preliminary (beta) science quality and data were released to the public for evaluation in September 2015. The product is available from the NASA Distributed Active Archive Center (DAAC) at the National Snow and Ice Data Center (NSIDC). This paper provides a summary of the L2_SM_P product and its validation against in situ ground measurements collected from different data sources. Initial in situ comparisons conducted through October 2015, at a limited number of core validation sites and several hundred sparse networks points, indicate that the V-pol Single Channel Algorithm (SCA-V) currently delivers the best performance amongst algorithms considered for L2_SM_P, based on several metrics. The accuracy of the soil moisture retrievals averaged over the core validation sites was 0.038 m3/m3 unbiased root-mean-square difference (ubRMSD), which meets the SMAP mission requirement of 0.040 m3/m3.