Estimating root zone soil moisture using near-surface observations from SMOS

Satellite-derived soil moisture provides more spatially and temporally extensive data than in situ observations. However, satellites can only measure water in the top few centimeters of the soil. Root zone soil moisture is more important, particularly in vegetated regions. Therefore estimates of root zone soil moisture must be inferred from near-surface soil moisture retrievals. The accuracy of this inference is contingent on the relationship between soil moisture in the near-surface and the soil moisture at greater depths. This study uses cross correlation analysis to quantify the association between near-surface and root zone soil moisture using in situ data from the United States Great Plains. Our analysis demonstrates that there is generally a strong relationship between near-surface (5–10 cm) and root zone (25–60 cm) soil moisture. An exponential decay filter is used to estimate root zone soil moisture using near-surface soil moisture derived from the Soil Moisture and Ocean Salinity (SMOS) satellite. Root zone soil moisture derived from SMOS surface retrievals is compared to in situ soil moisture observations in the United States Great Plains. The SMOS-based root zone soil moisture had a mean R 2 of 0.57 and a mean Nash–Sutcliffe score of 0.61 based on 33 stations in Oklahoma. In Nebraska, the SMOS-based root zone soil moisture had a mean R 2 of 0.24 and a mean Nash–Sutcliffe score of 0.22 based on 22 stations. Although the performance of the exponential filter method varies over space and time, we conclude that it is a useful approach for estimating root zone soil moisture from SMOS surface retrievals.

[1]  W. J. Shuttleworth,et al.  Integration of soil moisture remote sensing and hydrologic modeling using data assimilation , 1998 .

[2]  Bradley G. Illston,et al.  Evaluation of SMOS retrievals of soil moisture over the central United States with currently available in situ observations , 2012 .

[3]  Arnaud Mialon,et al.  The SMOS Soil Moisture Retrieval Algorithm , 2012, IEEE Transactions on Geoscience and Remote Sensing.

[4]  S. Sorooshian,et al.  To improve model soil moisture estimation in arid/semi-arid region using in situ and remote sensing information , 2012, Paddy and Water Environment.

[5]  D. Lawrence,et al.  Regions of Strong Coupling Between Soil Moisture and Precipitation , 2004, Science.

[6]  Jeffrey P. Walker,et al.  An EKF assimilation of AMSR-E soil moisture into the ISBA land surface scheme , 2009 .

[7]  C. Taylor,et al.  Afternoon rain more likely over drier soils , 2012, Nature.

[8]  R. Koster,et al.  Assimilation of GRACE terrestrial water storage into a land surface model: Evaluation and potential value for drought monitoring in western and central Europe , 2012 .

[9]  Thomas J. Jackson,et al.  The SMAP in situ soil moisture sensor testbed: Comparing in situ sensors for satellite validation , 2010, 2010 IEEE International Geoscience and Remote Sensing Symposium.

[10]  W. Wagner,et al.  Improving runoff prediction through the assimilation of the ASCAT soil moisture product , 2010 .

[11]  Bradley G. Illston,et al.  Seasonal to interannual variations of soil moisture measured in Oklahoma , 2004 .

[12]  P. Claps,et al.  An Analysis of the Soil Moisture Feedback on Convective and Stratiform Precipitation , 2008 .

[13]  Klaus Scipal,et al.  Validation of ERS scatterometer‐derived soil moisture data in the central part of the Duero Basin, Spain , 2005 .

[14]  W. Wagner,et al.  An Intercomparison of ERS-Scat and AMSR-E Soil Moisture Observations with Model Simulations over France , 2009 .

[15]  Philippe Richaume,et al.  Evaluation of SMOS Soil Moisture Products Over Continental U.S. Using the SCAN/SNOTEL Network , 2012, IEEE Transactions on Geoscience and Remote Sensing.

[16]  R. Mahmood,et al.  Quality Control of Soil Water Data in Applied Climate Information System—Case Study in Nebraska , 2010 .

[17]  L. Meng,et al.  Observational relationship of sea surface temperatures and precedent soil moisture with summer precipitation in the U.S. Great Plains , 2010 .

[18]  Yann Kerr,et al.  The SMOS Mission: New Tool for Monitoring Key Elements ofthe Global Water Cycle , 2010, Proceedings of the IEEE.

[19]  W. Wagner,et al.  A Method for Estimating Soil Moisture from ERS Scatterometer and Soil Data , 1999 .

[20]  Wade T. Crow,et al.  An ensemble Kalman filter dual assimilation of thermal infrared and microwave satellite observations of soil moisture into the Noah land surface model , 2012 .

[21]  Yann Kerr,et al.  Soil moisture retrieval from space: the Soil Moisture and Ocean Salinity (SMOS) mission , 2001, IEEE Trans. Geosci. Remote. Sens..

[22]  C. Albergel,et al.  From near-surface to root-zone soil moisture using an exponential filter: an assessment of the method based on in-situ observations and model simulations , 2008 .

[23]  W. Wagner,et al.  Soil moisture estimation through ASCAT and AMSR-E sensors: An intercomparison and validation study across Europe , 2011 .

[24]  Rezaul Mahmood,et al.  Relationship between soil moisture of near surface and multiple depths of the root zone under heterogeneous land uses and varying hydroclimatic conditions , 2007 .

[25]  Thomas L. Mote,et al.  Convection initiation along soil moisture boundaries in the southern Great Plains. , 2010 .

[26]  Jean-Pierre Wigneron,et al.  Monitoring of water and carbon fluxes using a land data assimilation system: a case study for southwestern France , 2010 .

[27]  Rezaul Mahmood,et al.  An Analysis of Simulated Long-Term Soil Moisture Data for Three Land Uses under Contrasting Hydroclimatic Conditions in the Northern Great Plains , 2004 .

[28]  Robert E. Dickinson,et al.  The Response of Soil Moisture to Long-Term Variability of Precipitation , 2002 .

[29]  C. Taylor,et al.  An observational case study of mesoscale atmospheric circulations induced by soil moisture , 2007 .

[30]  Jiancheng Shi,et al.  The Soil Moisture Active Passive (SMAP) Mission , 2010, Proceedings of the IEEE.

[31]  Jetse D. Kalma,et al.  One-dimensional soil moisture profile retrieval by assimilation of near-surface observations: a comparison of retrieval algorithms , 2001 .

[32]  R. Dickinson,et al.  Time Scales of Layered Soil Moisture Memory in the Context ofLand–Atmosphere Interaction , 2004 .

[33]  D. Bae,et al.  Climatic variability of soil water in the American Midwest: Part 2. Spatio-temporal analysis , 1994 .

[34]  J. M. Sabater,et al.  From near-surface to root-zone soil moisture using different assimilation techniques , 2007 .

[35]  Randal D. Koster,et al.  Global assimilation of satellite surface soil moisture retrievals into the NASA Catchment land surface model , 2005 .

[36]  Renee A. McPherson,et al.  A review of vegetation—atmosphere interactions and their influences on mesoscale phenomena , 2007 .

[37]  F. Aires,et al.  Sensitivity of satellite microwave and infrared observations to soil moisture at a global scale: Relationship of satellite observations to in situ soil moisture measurements , 2005 .

[38]  Luca Brocca,et al.  Soil Moisture Estimation in Alpine Catchments through Modeling and Satellite Observations , 2013 .

[39]  Yann Kerr,et al.  Validation of Soil Moisture and Ocean Salinity (SMOS) Soil Moisture Over Watershed Networks in the U.S. , 2012, IEEE Transactions on Geoscience and Remote Sensing.

[40]  W. Crow,et al.  The assimilation of remotely sensed soil brightness temperature imagery into a land surface model using Ensemble Kalman filtering: a case study based on ESTAR measurements during SGP97 , 2003 .

[41]  A. Robock,et al.  The International Soil Moisture Network: a data hosting facility for global in situ soil moisture measurements , 2011 .

[42]  Bradley G. Illston,et al.  Mesoscale Monitoring of Soil Moisture across a Statewide Network , 2008 .

[43]  R. Pielke.  Influence of the spatial distribution of vegetation and soils on the prediction of cumulus Convective rainfall , 2001 .

[44]  Dara Entekhabi,et al.  Solving the inverse problem for soil moisture and temperature profiles by sequential assimilation of multifrequency remotely sensed observations , 1994, IEEE Trans. Geosci. Remote. Sens..

[45]  R. Mahmood,et al.  Observed data-based assessment of relationships among soil moisture at various depths, precipitation, and temperature , 2012 .

[46]  Jetse D. Kalma,et al.  One-Dimensional Soil Moisture Profile Retrieval by Assimilation of Near-Surface Measurements: A Simplified Soil Moisture Model and Field Application , 2001 .

[47]  C. Albergel,et al.  An evaluation of ASCAT surface soil moisture products with in-situ observations in Southwestern France , 2008 .

[48]  C. Albergel,et al.  Assimilation of Soil Wetness Index and Leaf Area Index into the ISBA-A-gs land surface model: grassland case study , 2011 .

[49]  Delphis F. Levia,et al.  Soil moisture: A central and unifying theme in physical geography , 2011 .

[50]  Jeremy S. Pal,et al.  Pathways Relating Soil Moisture Conditions to Future Summer Rainfall within a Model of the Land-Atmosphere System , 2001 .

[51]  Jean-Christophe Calvet,et al.  From Near-Surface to Root-Zone Soil Moisture Using Year-Round Data , 2000 .

[52]  Jeffrey B. Basara,et al.  Linear relationships between root‐zone soil moisture and atmospheric processes in the planetary boundary layer , 2002 .