Enhancing Vegetation Monitoring: A Proposal for a Sentinel-2 Based Vegetation Health Index

Vegetation serves as a vital carbon sink, crucial for regulating CO2 and O2 levels in the atmosphere. However, the declining health of vegetation can contribute to a rise in greenhouse gas emissions. Utilizing remote sensing satellite imagery, we can effectively monitor global changes in vegetation health in near-real time. While various indices have been proposed for monitoring specific biochemical properties of vegetation, they often fail to detect health deterioration caused by multiple stressors like excessive heat, salinity, and water scarcity. All of the stress caused by these stressors may not be adequately identified by indices primarily sensitive to single-leaf parameters. Thus, this study introduces a novel vegetation health indicator that identifies vegetation stress-induced changes in chlorophyll, water, and protein content. This index was validated through lab-based spectroscopy experiments and global sensitivity analysis using physical models. Results from spectroscopy experiments highlight the limitations of the Normalized Difference Vegetation Index (NDVI) and the Normalized Difference Moisture Index (NDMI) in detecting specific stressors. However, the proposed index demonstrates proficiency in detecting a broader spectrum of stresses. Global sensitivity analysis indicates promising results, showing the sensitivity to chlorophyll and water content variations in the proposed index. Further analysis, focusing on the phenology of corn crops using Sentinel-2 data, demonstrates the usefulness of our new index (SVHI) in distinguishing characteristic vegetation changes while effectively differentiating non-vegetated areas like water bodies.