Kobayashi et al. (2026) Temporal and Spatial Associations of L-Band Fully Polarimetric SAR Metrics with Soil Moisture over a Wet Volcanic Ash Soil Field

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Identification

• Journal: Remote Sensing
• Year: 2026
• Date: 2026-09-25
• Authors: Daiki Kobayashi, Maiko Kawaguchi, Naoto Sato, Kosuke Noborio, Shinsuke Aoki
• DOI: 10.3390/rs18193316

Research Groups

• Institute of Geophysics and Meteorology (IGM)
• Department of Agricultural Engineering, University of [Institution]

Short Summary

This study investigates the relationship between L-band synthetic aperture radar (SAR) backscatter and soil moisture in a short-grass volcanic ash soil field. The results show that VV backscatter is a suitable indicator of field-averaged temporal soil moisture variation under wet conditions.

Objective

• Investigate the ability of L-band SAR to track field-averaged changes and within-field differences in soil moisture under wet conditions.

Study Configuration

• Spatial Scale: Field scale (short-grass volcanic ash soil field)
• Temporal Scale: Repeated observations over a period of time

Methodology and Data

• Models used: Improved Integral Equation Model (IIEM)
• Data sources: L-band SAR data from ALOS-2/PALSAR-2, Time-Domain Reflectometry (TDR) observations

Main Results

• VV backscatter shows a strong temporal association with volumetric water content (VWC), with Pearson r = 0.72 and Spearman ρ = 0.71.
• The IIEM driven by TDR-derived permittivity reproduces VV more closely than HH and HV, with baseline model–observation RMSEs of 1.41, 4.40, and 25.5 dB, respectively.

Contributions

• This study provides new insights into the relationship between L-band SAR backscatter and soil moisture under wet conditions.
• The results support VV as a suitable indicator of field-averaged temporal soil moisture variation.

Funding

• [Funding projects/programs/reference codes not specified in the paper]

Citation

@article{Kobayashi2026Temporal,
  author = {Kobayashi, Daiki and Kawaguchi, Maiko and Sato, Naoto and Noborio, Kosuke and Aoki, Shinsuke},
  title = {Temporal and Spatial Associations of L-Band Fully Polarimetric SAR Metrics with Soil Moisture over a Wet Volcanic Ash Soil Field},
  journal = {Remote Sensing},
  year = {2026},
  doi = {10.3390/rs18193316},
  url = {https://doi.org/10.3390/rs18193316}
}