README file 

Created by Rolf Reichle and Qing Liu, 2 August 2019

This directory contains the SMAP Nature Run datasets used in the 
following paper:

 Reichle, R. H., and Coauthors (2019), Version 4 of the SMAP Level-4 
 Soil Moisture Algorithm and Data Product, Journal of Advances in 
 Modeling Earth Systems, doi:10.1029/2019MS001729.

The data are provided in the self-describing hdf-5 file format.

The file structure matches that of the SMAP Level-4 Surface and
Root-Zone Soil Moisture (L4_SM) product, specifically, the "Geophysical Data"
file Collection:

 Reichle, R., G. De Lannoy, R. D. Koster, W. T. Crow, J. S. Kimball, and 
 Q. Liu. 2018. SMAP L4 Global 3-hourly 9 km EASE-Grid Surface and Root Zone 
 Soil Moisture Geophysical Data, Version 4.  Boulder, Colorado USA. 
 NASA National Snow and Ice Data Center Distributed Active Archive Center.
 doi: https://doi.org/10.5067/KPJNN2GI1DQR. 

for which documentation is at https://nsidc.org/data/SPL4SMGP/.

However, the SMAP Nature Run files only contain the following data fields:

 sm_surface          [m3 m-3]
 sm_rootzone         [m3 m-3]
 total_runoff_flux   [kg m-2 s-1]

The latter is equivalent to the sum of "baseflow_flux" and 
"overland_runoff_flux" in the L4_SM product.

Note that in Reichle et al. (2019), "SMAP_Nature_v4.1" is referred to as 
"NR3030", and "SMAP_Nature_v7.2" is referred to as "NR4030".

Data are provided for the period from April 2015 to March 2018.

The total data volume is approximately 236 GB.

Further documentation is provided in Reichle et al. (2019) and references
therein.

As a condition of using the SMAP Nature Run data, please reference

 Reichle, R. H., and Coauthors (2019), Version 4 of the SMAP Level-4 
 Soil Moisture Algorithm and Data Product, Journal of Advances in 
 Modeling Earth Systems, doi:10.1029/2019MS001729.


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