TY - JOUR
T1 - Evaluation of SMAP soil moisture relative to five other satellite products using the climate reference network measurements over USA
AU - Stillman, Susan
AU - Zeng, Xubin
N1 - Funding Information: Manuscript received August 17, 2017; revised November 13, 2017, January 18, 2018, and April 23, 2018; accepted May 3, 2018. Date of publication June 1, 2018; date of current version October 25, 2018. This work was supported by the NASA SMAP Program under Grant NNX16AN37G. (Corresponding author: Susan Stillman.) S. Stillman is with the Division of Hydrologic Sciences, Desert Research Institute, Las Vegas, NV 89119 USA (e-mail: [email protected]). X. Zeng is with the Department Hydrology and Atmospheric Sciences, The University of Arizona, Tucson, AZ 85721 USA. This paper has supplementary downloadable material available at http://ieeexplore.ieee.org, provided by the author. Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/TGRS.2018.2835316 Publisher Copyright: © 2018 IEEE.
PY - 2018/11
Y1 - 2018/11
N2 - Satellite platforms provide a unique opportunity to retrieve global soil moisture. The Level 3 soil moisture (L3SMP), enhanced Level 3 soil moisture (L3SMP-E) and Level 4 surface soil moisture (L4SM) products of the latest soil moisture satellite mission, Soil Moisture Active Passive (SMAP), are evaluated relative to five other satellite products using the Climate Reference Network (CRN) with more than 110 stations (each with three in situ probes) over USA from 2009 to present. This large number of stations allows for the categorization of SMAP performance based on land cover types, complementing prior efforts based on the few core validation areas with many in situ observations within a single satellite pixel. The SMAP as well as Aquarius products clearly outperform the other products. Over all land cover types, L3SMP, L3SMP-E, and L4SM are better in the summer than in the winter and they perform best over short vegetation. L4SM has higher correlations compared with CRN than L3SMP over tall and short vegetation whereas L3SMP has higher correlations over crops. On average, L3SMP-E performs as well as L3SMP. There is a mismatch between the point in situ measurements and satellite pixel retrievals driven by subpixel precipitation variability, and its impact on these results is also assessed.
AB - Satellite platforms provide a unique opportunity to retrieve global soil moisture. The Level 3 soil moisture (L3SMP), enhanced Level 3 soil moisture (L3SMP-E) and Level 4 surface soil moisture (L4SM) products of the latest soil moisture satellite mission, Soil Moisture Active Passive (SMAP), are evaluated relative to five other satellite products using the Climate Reference Network (CRN) with more than 110 stations (each with three in situ probes) over USA from 2009 to present. This large number of stations allows for the categorization of SMAP performance based on land cover types, complementing prior efforts based on the few core validation areas with many in situ observations within a single satellite pixel. The SMAP as well as Aquarius products clearly outperform the other products. Over all land cover types, L3SMP, L3SMP-E, and L4SM are better in the summer than in the winter and they perform best over short vegetation. L4SM has higher correlations compared with CRN than L3SMP over tall and short vegetation whereas L3SMP has higher correlations over crops. On average, L3SMP-E performs as well as L3SMP. There is a mismatch between the point in situ measurements and satellite pixel retrievals driven by subpixel precipitation variability, and its impact on these results is also assessed.
KW - Hydrology
KW - remote sensing
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U2 - 10.1109/TGRS.2018.2835316
DO - 10.1109/TGRS.2018.2835316
M3 - Article
SN - 0196-2892
VL - 56
SP - 6296
EP - 6305
JO - IEEE Transactions on Geoscience and Remote Sensing
JF - IEEE Transactions on Geoscience and Remote Sensing
IS - 11
M1 - 8370803
ER -