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7. High-Resolution Soil-Moisture Maps Over Landslide Regions in Northern California Grassland Derived From SAR Backscattering Coefficients

Author

Liao, Tien-Hao, Kim, Seung-Bum, Handwerger, Alexander L, Fielding, Eric J, Cosh, Michael H, and Schulz, William H

Subjects
Geomatic Engineering, Engineering, Terrain factors, Soil moisture, Poles and towers, Synthetic aperture radar, Soil measurements, Monitoring, Moisture measurement, Landslides, radar remote sensing, soil moisture, Physical Geography and Environmental Geoscience, Artificial Intelligence and Image Processing, Physical geography and environmental geoscience, Geomatic engineering, Applied computing
Abstract

Slow-moving landslides are destabilized by accumulated precipitation and consequent soil moisture. Yet, the continuous high-resolution soil-moisture measurements needed to aid the understanding of landslide processes are generally absent in steep terrain. Here, we produce soil-moisture time-series maps for a seasonally active grassland landslide in the northern California coast ranges, USA, using backscattering coefficients from NASA's uninhabited aerial vehicle synthetic aperture radar at 6-m resolution. A physically based radar scattering model is used to retrieve the near-surface (5-cm depth) soil moisture for the landslide. Both forward modeling (backscattering estimation) and the retrieval (soil-moisture validation) show good agreement. The root-mean-square errors (RMSE) for vertical transmit vertical receive (VV) and horizontal transmit horizontal receive (HH) polarizations in forward model comparison are 1.93 dB and 1.88 dB, respectively. The soil-moisture retrieval shows unbiased RMSE of 0.054 m3/m3. Our successful retrieval benefits from the surface and double-bounce scattering, which is common in grasslands. The retrieved maps show saturated wetness conditions within the active landslide boundaries. We also performed sensitivity tests for incidence angle and found that the retrieval is weakly dependent on the angle, especially while using copolarized HH and VV together. Using the two copolarized inputs, the retrieval is also not sensitive to the change of orientation angles of grass cylinders. The physical model inversion presented here can be generally applied for soil-moisture retrieval in areas with the same vegetation cover types in California.

Published
2021

14. Sentinel-1 soil moisture at 1 km resolution: a validation study

Author

Balenzano, Anna, Mattia, Francesco, Satalino, Giuseppe, Lovergine, Francesco P., Palmisano, Davide, Peng, Jian, Marzahn, Philip, Wegmüller, Urs, Cartus, Oliver, Dąbrowska-Zielińska, Katarzyna, Musial, Jan P., Davidson, Malcolm W.J., Pauwels, Valentijn R.N., Cosh, Michael H., McNairn, Heather, Johnson, Joel T., Walker, Jeffrey P., Yueh, Simon H., Entekhabi, Dara, Kerr, Yann H., and Jackson, Thomas J.

Published
2021
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16. Validation of SMAP soil moisture for the SMAPVEX15 field campaign using a hyper‐resolution model

Author

Cai, Xitian, Pan, Ming, Chaney, Nathaniel W, Colliander, Andreas, Misra, Sidharth, Cosh, Michael H, Crow, Wade T, Jackson, Thomas J, and Wood, Eric F

Subjects
Physical Geography and Environmental Geoscience, Civil Engineering, Environmental Engineering
Abstract

Accurate global mapping of soil moisture is the goal of the Soil Moisture Active Passive (SMAP) mission, which is expected to improve the estimation of water, energy, and carbon exchanges between the land and the atmosphere. Like other satellite products, the SMAP soil moisture retrievals need to be validated, with the validation relying heavily on in situ measurements. However, a one-to-one comparison is ill advised due to the spatial mismatch of the large SMAP footprint (∼40 km) and the point scale in situ measurements. This study uses a recently developed hyper-resolution land surface model—HydroBlocks—as a tool to upscale in situ soil moisture measurements for the SMAPVEX15 (SMAP Validation Experiment 2015) field campaign during 2–18 August 2015. Calibrated against in situ observation, HydroBlocks shows a satisfactory Kling-Gupta efficiency (KGE) of 0.817 and RMSE of 0.019 m3/m3 for the calibration period. These results indicate that HydroBlocks can be used to upscale in situ measurements for this site. Different from previous studies, here in situ measurements are upscaled using a land surface model without bias correction. The upscaled soil moisture is then used to evaluate SMAP (passive) soil moisture products. The comparison of the upscaled network to SMAP shows that the retrievals are generally able to capture the areal-averaged soil moisture temporal variations. However, SMAP appears to be oversensitive to summer precipitation. We expect these findings can be used to improve the SMAP soil moisture product and thus facilitate its usage in studying the water, energy, and carbon cycles.

Published
2017

17. A roadmap for high-resolution satellite soil moisture applications – confronting product characteristics with user requirements

Author

Peng, Jian, Albergel, Clement, Balenzano, Anna, Brocca, Luca, Cartus, Oliver, Cosh, Michael H., Crow, Wade T., Dabrowska-Zielinska, Katarzyna, Dadson, Simon, Davidson, Malcolm W.J., de Rosnay, Patricia, Dorigo, Wouter, Gruber, Alexander, Hagemann, Stefan, Hirschi, Martin, Kerr, Yann H., Lovergine, Francesco, Mahecha, Miguel D., Marzahn, Philip, Mattia, Francesco, Musial, Jan Pawel, Preuschmann, Swantje, Reichle, Rolf H., Satalino, Giuseppe, Silgram, Martyn, van Bodegom, Peter M., Verhoest, Niko E.C., Wagner, Wolfgang, Walker, Jeffrey P., Wegmüller, Urs, and Loew, Alexander

Published
2021
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25. Development of SMAP Retrievals for Forested Regions: SMAPVEX19-22 and SMAPVEX22-Boreal

Author

Colliander, Andreas, Cosh, Michael H, Berg, Aaron, Misra, Sidharth, Thomas, Jaison, Bourgeau-Chavez, Laura, Kelly, Vicky, Kraatz, Simon, Siqueira, Paul, Roy, Alexandre, Helgason, Warren, Magagi, Ramata, Lakhankar, Tarendra, Ogut, Mehmet, Chaubell, Julian, Dunbar, Scott, Famiglietti, Jay, Konings, Alexandra, Kurum, Mehmet, Entekhabi, Dara, and Yueh, Simon H

Published
2022

26. Development of SMAP Retrievals for Forested Regions: SMAPVEX19-22 and SMAPVEX22-Boreal

Author

Yueh, Simon H, Entekhabi, Dara, Kurum, Mehmet, Konings, Alexandra, Famiglietti, Jay, Dunbar, Scott, Chaubell, Julian, Ogut, Mehmet, Lakhankar, Tarendra, Magagi, Ramata, Helgason, Warren, Roy, Alexandre, Siqueira, Paul, Kraatz, Simon, Kelly, Vicky, Bourgeau-Chavez, Laura, Thomas, Jaison, Misra, Sidharth, Berg, Aaron, Cosh, Michael H, and Colliander, Andreas

Abstract

The retrieval of soil moisture (SM) under forest canopy has long been an important goal for low frequency remote sensing. The NASA Soil Moisture Active Passive (SMAP) mission is engaged at three separate experiment sites to improve its SM retrieval algorithm in forested areas. Two of the sites are located in the deciduous forest region in Massachusetts and New York, US and one is located in southern boreal forest zone in Saskatchewan, Canada. Each site has a SM measurement network of about 20 stations spread out over an area of about 30 km, which covers the SMAP radiometer footprint. In 2022, intensive observations will be carried out at each site which involve deployments of an airborne instrument, which is similar to the SMAP instrument, and intensive manual measurements of SM, surface and vegetation. The measurements also include tower-based radiometer observations with ground truth measurements within the instrument footprint. Here we show some early results using the networks and SMAP measurements to analyze the sensitivity of the SMAP L-band measurements to SM changes in forested area and the impact of the vegetation to the signal. The results suggest an upper limit for vegetation attenuation accounting for surface roughness effect and relate that to the values used in the current SMAP SM products.

Published
2022

38. The SMAP mission combined active-passive soil moisture product at 9 km and 3 km spatial resolutions

Author

Das, Narendra N., Entekhabi, Dara, Dunbar, R. Scott, Colliander, Andreas, Chen, Fan, Crow, Wade, Jackson, Thomas J., Berg, Aaron, Bosch, David D., Caldwell, Todd, Cosh, Michael H., Collins, Chandra H., Lopez-Baeza, Ernesto, Moghaddam, Mahta, Rowlandson, Tracy, Starks, Patrick J., Thibeault, Marc, Walker, Jeffrey P., Wu, Xiaoling, O'Neill, Peggy E., Yueh, Simon, and Njoku, Eni G.

Published
2018
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42. SMAP Validation Experiment 2019-2021 (SMAPVEX19-21): Detection of Soil Moisture Under Temperate Forest Canopy

Author

Yueh, Simon H, O’Neill, Peggy, Entekhabi, Dara, Kurum, Mehmet, Konings, Alexandra, Kraatz, Simon, Lakhankar, Tarendra, Roy, Alexandre, Siqueira, Paul, Kelly, Vicky, Bourgeau-Chavez, Laura, Misra, Sidharth, Cosh, Michael H, and Colliander, Andreas

Abstract

The retrieval of soil moisture under forest canopy has long been an important goal for low frequency remote sensing. The NASA mission started a dedicated field experiment in May 2019 by deploying two temporary soil moisture networks in northeast US that cover two separate SMAP pixels with variable degree of forest cover. The measurements will be augmented with two intensive observation periods (IOP). The first IOP is planned for July and the other one for October. The IOPs will see deployment of the airborne PALS (Passive Active L-band sensor) instrument, which is similar to the SMAP instrument, and intensive manual measurements of soil moisture and vegetation. The measurements also include tower-based radiometer observations with ground truth measurements within the instrument footprint. The early results have shown that the SMAP measurement signal at L-band is sensitive to soil moisture changes observed on the ground.

Published
2021

46. Calibration of an impedance probe for estimation of surface soil water content over large regions

Author

Cosh, Michael H, Jackson, Thomas J, Bindlish, Rajat, Famiglietti, James S, and Ryu, Dongryeol

Subjects
land surface hydrology, soil moisture, instrument calibration, field experiments, gravimetric sampling, error analysis
Abstract

Large region surface soil moisture estimates are important for both hydrologic modeling and remote sensing applications. For soil moisture monitoring, gravimetric soil moisture sampling is reliable; however, it requires a significant effort to gather and process samples. Portable impedance probes serve as a valuable alternative to destructive gravimetric sampling. These probes measure the dielectric properties of the soil–water–air mixture from which we can infer the volumetric soil moisture. As part of recent large-scale experiments in the summers of 2002 and 2003, three different methods for calibrating impedance probes were investigated with the support of coincident gravimetric samples. Field specific calibration improved the accuracy of the probe from greater than ±5% volumetric soil moisture (using the generalized calibration) to less than ±4%. In addition, a significant amount of bias (∼2%) was eliminated. It was also determined that field specific calibration removes a bias due to bulk density variations. Based upon these results it was concluded that the generalized calibration is adequate for estimation of diverse conditions. For studies with more stringent accuracy requirements, field specific calibration is necessary because of reduced bias and error.

Published
2005

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