Deng et al. (2026) Effects of aboveground biomass and soil moisture drought on VOD-based global isohydricity estimates

Identification

• Journal: Remote Sensing of Environment
• Year: 2026
• Date: 2026-09-04
• Authors: Yuanzhizi Deng, Yao Zhang
• DOI: 10.1016/j.rse.2026.115641

Research Groups

• Institute of Carbon Neutrality, Sino-French Institute for Earth System Science, College of Urban and Environmental Sciences, Peking University, Beijing, China.

Short Summary

This study evaluates the robustness of two VOD-based isohydricity metrics ($\sigma$ and $R{slope}$), concluding that $R{slope}$ is significantly more stable and less influenced by biomass dynamics and dataset variations than $\sigma$.

Objective

• To evaluate the robustness of VOD-derived ecosystem isohydricity metrics ($\sigma$ and $R_{slope}$) by assessing the influence of aboveground biomass dynamics and soil moisture drought events.

Study Configuration

• Spatial Scale: Global.
• Temporal Scale: Diurnal and seasonal.

Methodology and Data

• Models used: VOD-derived isohydricity metrics ($\sigma$ and $R_{slope}$).
• Data sources: Multiple passive microwave Vegetation Optical Depth (VOD) datasets and eddy covariance measurements.

Main Results

• Metric Sensitivity: The $\sigma$ metric is strongly influenced by biomass dynamics, where higher seasonal biomass variations consistently result in higher $\sigma$ values.
• Metric Robustness: $R_{slope}$ is largely independent of biomass and demonstrates greater spatial consistency across different VOD datasets and microwave frequencies.
• Drought Sampling: Implementing binning to account for uneven sampling across drought severity improves the relationship between $R_{slope}$ and isohydricity derived from eddy covariance measurements.
• Reliability: A reliability map indicates that VOD-based isohydricity estimates are most dependable in seasonally dry regions characterized by moderate biomass.

Contributions

• The study identifies fundamental differences between VOD-based isohydricity metrics, establishing $R_{slope}$ as a more robust proxy for ecosystem water-use strategies. It highlights the necessity of accounting for biomass dynamics and drought sampling to avoid biases in large-scale remote sensing assessments of isohydricity.

Funding

• Not specified in the provided text.

Citation

@article{Deng2026Effects,
  author = {Deng, Yuanzhizi and Zhang, Yao},
  title = {Effects of aboveground biomass and soil moisture drought on VOD-based global isohydricity estimates},
  journal = {Remote Sensing of Environment},
  year = {2026},
  doi = {10.1016/j.rse.2026.115641},
  url = {https://doi.org/10.1016/j.rse.2026.115641}
}