Downscaling of SMAP Soil Moisture Using Land Surface Temperature and Vegetation Data

Remotely sensed soil moisture retrieved by the Soil Moisture Active and Passive (SMAP) sensor is currently provided at a 9-km grid resolution. Although valuable, some applications in weather, agriculture, ecology, and watershed hydrology require soil moisture at a higher spatial resolution. In this study, a passive microwave soil moisture downscaling algorithm based on thermal inertia theory was improved for use with SMAP and applied to a data set collected at a field experiment. This algorithm utilizes a normalized difference vegetation index (NDVI) modulated relationship between daytime soil moisture and daily temperature change modeled using output variables from the land surface model of the North American Land Data Assimilation System (NLDAS) and remote sensing data from the Moderate-Resolution Imaging Spectroradiometer (MODIS) and Advanced Very High Resolution Radiometer (AVHRR). The reference component of the algorithm was developed at the NLDAS grid size (12.5 km) to downscale the SMAP Level 3 radiometer-based 9-km soil moisture to 1 km. The downscaled results were validated using data acquired in Soil Moisture Active Passive Validation Experiment 2015 (SMAPVEX15) that included in situ soil moisture and Passive Active L-band System (PALS) airborne instrument observations. The resulting downscaled SMAP estimates better characterize soil moisture spatial and temporal variability and have better overall validation metrics than the original SMAP soil moisture estimates. Additionally, the overall accuracy of the downscaled SMAP soil moisture is comparable to the PALS high spatial resolution soil moisture retrievals. The method demonstrated in this study downscales satellite soil moisture to produce a 1-km product that is not site specific and could be applied to other regions of the world using the publicly available NLDAS/Global Land Data Assimilation System data.

[1]  Venkat Lakshmi,et al.  Soil moisture retrieval using the passive/active L- and S-band radar/radiometer , 2003, IEEE Trans. Geosci. Remote. Sens..

[2]  Eric F. Wood,et al.  Evaluation of Special Sensor Microwave/Imager Satellite Data for Regional Soil Moisture Estimation over the Red River Basin , 1997 .

[3]  T. Jackson,et al.  Retrieving soil moisture for non-forested areas using PALS radiometer measurements in SMAPVEX12 field campaign , 2016 .

[4]  Lifeng Luo,et al.  An intercomparison of soil moisture fields in the North American Land Data Assimilation System (NLDAS) , 2003 .

[5]  Irena Hajnsek,et al.  Investigation of SMAP Fusion Algorithms With Airborne Active and Passive L-Band Microwave Remote Sensing , 2016, IEEE Transactions on Geoscience and Remote Sensing.

[6]  V. Lakshmi,et al.  Characterizing subpixel variability of low resolution radiometer derived soil moisture using high resolution radar data , 2008 .

[7]  Yann Kerr,et al.  Downscaling SMOS-Derived Soil Moisture Using MODIS Visible/Infrared Data , 2011, IEEE Transactions on Geoscience and Remote Sensing.

[8]  Jie Wang,et al.  Spatial Downscaling of Satellite Soil Moisture Data Using a Vegetation Temperature Condition Index , 2016, IEEE Transactions on Geoscience and Remote Sensing.

[9]  Li Fang,et al.  An inter-comparison of soil moisture data products from satellite remote sensing and a land surface model , 2016, Int. J. Appl. Earth Obs. Geoinformation.

[10]  M. Ek,et al.  Validation of Noah-Simulated Soil Temperature in the North American Land Data Assimilation System Phase 2 , 2013 .

[11]  A. Colliandera,et al.  Development and assessment of the SMAP enhanced passive soil moisture product , 2017 .

[12]  Seungbum Hong,et al.  Effects of vegetation and soil moisture on the simulated land surface processes from the coupled WRF/Noah model , 2009 .

[13]  Venkat Lakshmi,et al.  Retrieval of soil moisture from passive and active L/S band sensor (PALS) observations during the Soil Moisture Experiment in 2002 (SMEX02) , 2004 .

[14]  Thomas J. Jackson,et al.  Validation of Advanced Microwave Scanning Radiometer Soil Moisture Products , 2010, IEEE Transactions on Geoscience and Remote Sensing.

[15]  Ainong Li,et al.  A Downscaling Method for Improving the Spatial Resolution of AMSR-E Derived Soil Moisture Product Based on MSG-SEVIRI Data , 2013, Remote. Sens..

[16]  Yoann Malbéteau,et al.  Performance Metrics for Soil Moisture Downscaling Methods: Application to DISPATCH Data in Central Morocco , 2015, Remote. Sens..

[17]  A. Al Bitar,et al.  An improved algorithm for disaggregating microwave-derived soil moisture based on red, near-infrared and thermal-infrared data , 2010 .

[18]  Yann Kerr,et al.  Assessment of the SMAP Passive Soil Moisture Product , 2016, IEEE Transactions on Geoscience and Remote Sensing.

[19]  T. Jackson,et al.  Watershed scale temporal and spatial stability of soil moisture and its role in validating satellite estimates , 2004 .

[20]  K. Mitchell,et al.  A parameterization of snowpack and frozen ground intended for NCEP weather and climate models , 1999 .

[21]  Venkat Lakshmi,et al.  Remote Sensing of Soil Moisture , 2013 .

[22]  Thomas J. Jackson,et al.  Soil moisture retrieval from AMSR-E , 2003, IEEE Trans. Geosci. Remote. Sens..

[23]  Zhao-Liang Li,et al.  A physics-based algorithm for retrieving land-surface emissivity and temperature from EOS/MODIS data , 1997, IEEE Trans. Geosci. Remote. Sens..

[24]  Alexander Loew,et al.  Evaluation of soil moisture downscaling using a simple thermal-based proxy – the REMEDHUS network (Spain) example , 2015 .

[25]  Venkat Lakshmi,et al.  Passive/active microwave soil moisture retrieval disaggregation using SMAPVEX12 data , 2014, Asia-Pacific Environmental Remote Sensing.

[26]  Yann Kerr,et al.  A Simple Method to Disaggregate Passive Microwave-Based Soil Moisture , 2008, IEEE Transactions on Geoscience and Remote Sensing.

[27]  Y. Xue,et al.  Modeling of land surface evaporation by four schemes and comparison with FIFE observations , 1996 .

[28]  Niko E. C. Verhoest,et al.  A review of spatial downscaling of satellite remotely sensed soil moisture , 2017 .

[29]  Terri S. Hogue,et al.  Improving Spatial Soil Moisture Representation Through Integration of AMSR-E and MODIS Products , 2012, IEEE Transactions on Geoscience and Remote Sensing.

[30]  C. Bertoia,et al.  Evaluation of Special Sensor Microwave/Imager sea-ice products , 1999, IEEE 1999 International Geoscience and Remote Sensing Symposium. IGARSS'99 (Cat. No.99CH36293).

[31]  Enrique R. Vivoni,et al.  Soil moisture downscaling across climate regions and its emergent properties , 2011 .

[32]  J. D. Tarpley,et al.  Evaluation of the North American Land Data Assimilation System over the southern Great Plains during the warm season , 2003 .

[33]  Ahmad Al Bitar,et al.  Self-calibrated evaporation-based disaggregation of SMOS soil moisture: An evaluation study at 3 km and 100 m resolution in Catalunya, Spain , 2013 .

[34]  J. D. Tarpley,et al.  Implementation of Noah land surface model advances in the National Centers for Environmental Prediction operational mesoscale Eta model , 2003 .

[35]  Wade T. Crow,et al.  Validation and scaling of soil moisture in a semi-arid environment: SMAP validation experiment 2015 (SMAPVEX15) , 2017 .

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

[37]  C. Tucker.  Red and photographic infrared linear combinations for monitoring vegetation , 1979 .

[38]  Li Jia,et al.  Retrieving High-Resolution Surface Soil Moisture by Downscaling AMSR-E Brightness Temperature Using MODIS LST and NDVI Data , 2014, IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing.

[39]  B. Fang,et al.  Soil moisture at watershed scale: Remote sensing techniques , 2014 .

[40]  T. Jackson,et al.  III. Measuring surface soil moisture using passive microwave remote sensing , 1993 .

[41]  Minha Choi,et al.  A microwave-optical/infrared disaggregation for improving spatial representation of soil moisture using AMSR-E and MODIS products , 2012 .

[42]  Venkat Lakshmi,et al.  Land surface air temperature mapping using TOVS and AVHRR , 2001 .

[43]  Thomas J. Schmugge,et al.  Remote Sensing of Soil Moisture with Microwave Radiometers , 1983 .

[44]  Kaniska Mallick,et al.  Estimating volumetric surface moisture content for cropped soils using a soil wetness index based on surface temperature and NDVI , 2009 .

[45]  Adriano Camps,et al.  A Change Detection Algorithm for Retrieving High-Resolution Soil Moisture From SMAP Radar and Radiometer Observations , 2009, IEEE Transactions on Geoscience and Remote Sensing.

[46]  W. Kustas,et al.  A verification of the 'triangle' method for obtaining surface soil water content and energy fluxes from remote measurements of the Normalized Difference Vegetation Index (NDVI) and surface e , 1997 .

[47]  B. Choudhury,et al.  Investigation of effect of heterogeneities in vegetation and rainfall on simulated SSM/I brightness temperatures , 1997 .

[48]  D. Entekhabi,et al.  A CHANGE DETECTION ALGORITHM FOR RETRIEVING HIGH-RESOLUTION SURFACE SOIL MOISTURE FROM SMAP L-BAND RADAR AND RADIOMETER OBSERVATIONS , 2009 .

[49]  Thomas J. Jackson,et al.  Passive Microwave Soil Moisture Downscaling Using Vegetation Index and Skin Surface Temperature , 2013 .

[50]  Venkat Lakshmi,et al.  The role of satellite remote sensing in the Prediction of Ungauged Basins , 2004 .

[51]  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.

[52]  T. Schmugge,et al.  Mapping surface soil moisture with microwave radiometers , 1994 .

[53]  M. Minacapilli,et al.  High resolution remote estimation of soil surface water content by a thermal inertia approach , 2009 .

[54]  Wade T. Crow,et al.  SMAP Handbook–Soil Moisture Active Passive: Mapping Soil Moisture and Freeze/Thaw from Space , 2014 .

[55]  T. Carlson.  An Overview of the “Triangle Method” for Estimating Surface Evapotranspiration and Soil Moisture from Satellite Imagery , 2007, Sensors (Basel, Switzerland).

[56]  Venkat Lakshmi,et al.  AMSR‐E Soil Moisture Disaggregation Using MODIS and NLDAS Data , 2014 .

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

[58]  Enrique R. Vivoni,et al.  Downscaling soil moisture in the southern Great Plains through a calibrated multifractal model for land surface modeling applications , 2010 .

[59]  Adriano Camps,et al.  Impact of day/night time land surface temperature in soil moisture disaggregation algorithms , 2016 .

[60]  J. D. Tarpley,et al.  The multi‐institution North American Land Data Assimilation System (NLDAS): Utilizing multiple GCIP products and partners in a continental distributed hydrological modeling system , 2004 .

[61]  Thomas J. Jackson,et al.  High-resolution change estimation of soil moisture using L-band radiometer and Radar observations made during the SMEX02 experiments , 2006, IEEE Transactions on Geoscience and Remote Sensing.

[62]  Venkat Lakshmi,et al.  A soil‐canopy‐atmosphere model for use in satellite microwave remote sensing , 1997 .

[63]  Venkat Lakshmi,et al.  Evaluating Bias‐Corrected AMSR‐E Soil Moisture using in situ Observations and Model Estimates , 2013 .

[64]  A. Al Bitar,et al.  Overview of SMOS performance in terms of global soil moisture monitoring after six years in operation , 2016 .

[65]  J. D. Tarpley,et al.  Real‐time and retrospective forcing in the North American Land Data Assimilation System (NLDAS) project , 2003 .

[66]  Thomas J. Jackson,et al.  Global Soil Moisture From the Aquarius/SAC-D Satellite: Description and Initial Assessment , 2015, IEEE Geoscience and Remote Sensing Letters.

[67]  Thomas J. Schmugge,et al.  An interpretation of methodologies for indirect measurement of soil water content , 1995 .

[68]  B. Choudhury,et al.  Effect of surface roughness on the microwave emission from soils , 1979 .

[69]  Wade T. Crow,et al.  Validation of SMAP soil moisture for the SMAPVEX15 field campaign using a hyper‐resolution model , 2017 .

[70]  S. Sánchez-Ruiz,et al.  Combining SMOS with visible and near/shortwave/thermal infrared satellite data for high resolution soil moisture estimates , 2014 .

[71]  Venkat Lakshmi,et al.  Use of the scanning multichannel microwave radiometer (SMMR) to retrieve soil moisture and surface temperature over the central United States , 2004, IEEE Transactions on Geoscience and Remote Sensing.

[72]  Seungbum Hong,et al.  The influence of the land surface on hydrometeorology and ecology: new advances from modeling and satellite remote sensing , 2011 .