Skip to Main content Skip to Navigation
New interface
Journal articles

Assessment of the SMAP Level-4 Surface and Root-Zone Soil Moisture Product Using In Situ Measurements

Abstract : The Soil Moisture Active Passive (SMAP) mission Level-4 Surface and Root-Zone Soil Moisture (L4_SM) data product is generated by assimilating SMAP L-band brightness temperature observations into the NASA Catchment land surface model. The L4_SM product is available from 31 March 2015 to present (within 3 days from real time) and provides 3-hourly, global, 9-km resolution estimates of surface (0-5 cm) and root-zone (0-100 cm) soil moisture and land surface conditions. This study presents an overview of the L4_SM algorithm, validation approach, and product assessment versus in situ measurements. Core validation sites provide spatially averaged surface (root zone) soil moisture measurements for 43 (17) "reference pixels" at 9- and 36-km gridcell scales located in 17 (7) distinct watersheds. Sparse networks provide point-scale measurements of surface (root zone) soil moisture at 406 (311) locations. Core validation site results indicate that the L4_SM product meets its soil moisture accuracy requirement, specified as an unbiased RMSE (ubRMSE, or standard deviation of the error) of 0.04 m3 m-3 or better. The ubRMSE for L4_SM surface (root zone) soil moisture is 0.038 m3 m-3 (0.030 m3 m-3) at the 9-km scale and 0.035 m3 m-3 (0.026 m3 m-3) at the 36-km scale. The L4_SM estimates improve (significantly at the 5% level for surface soil moisture) over model-only estimates, which do not benefit from the assimilation of SMAP brightness temperature observations and have a 9-km surface (root zone) ubRMSE of 0.042 m3 m-3 (0.032 m3 m-3). Time series correlations exhibit similar relative performance. The sparse network results corroborate these findings over a greater variety of climate and land cover conditions.
Complete list of metadata

https://hal-insu.archives-ouvertes.fr/insu-03668266
Contributor : Nathalie POTHIER Connect in order to contact the contributor
Submitted on : Monday, May 16, 2022 - 1:53:59 PM
Last modification on : Wednesday, November 16, 2022 - 11:46:08 AM

File

[15257541 - Journal of Hydrome...
Publisher files allowed on an open archive

Licence


Distributed under a Creative Commons Attribution 4.0 International License

Identifiers

Collections

Citation

Rolf H. Reichle, Gabrielle J. M. de Lannoy, Qing Liu, Joseph V. Ardizzone, Andreas Colliander, et al.. Assessment of the SMAP Level-4 Surface and Root-Zone Soil Moisture Product Using In Situ Measurements. Journal of Hydrometeorology, 2017, 18, pp.2621-2645. ⟨10.1175/JHM-D-17-0063.1⟩. ⟨insu-03668266⟩

Share

Metrics

Record views

24

Files downloads

21