Synergistic Satellite Assessment of Global Vegetation Health in Relation to ENSO-Induced Droughts and Pluvials

We used environmental metrics developed from multi-source satellite observations to quantify the global influence of El Nino-Southern Oscillation (ENSO) events on surface wetting and drying anomalies, and their impact on vegetation health. The environmental metrics included a microwave surface wetness index (ASWI) incorporating near-surface atmospheric vapor pressure deficit (VPD), volumetric soil moisture (VSM), and land surface fractional water cover (FW) derived from Advanced Microwave Scanning Radiometer (AMSR) observations, and the vegetation health index (VHI) derived from NOAA Advanced Very High Resolution Radiometer (AVHRR) observations. The combined ASWI and VHI analysis reveals complex ENSO related impacts on the distribution of water availability to plant communities, and variable vegetation sensitivity to associated drought and pluvial events. A delayed VHI response to changes in surface wetness (up to 3.4 months) was observed, whereby the ASWI may provide an effective forecast predictor of climate impacts on vegetation health. The intense 2015/2016 El Nino event coincided with strong ASWI and VHI latitudinal correspondence (R >= 0.73). The cascading impacts of climate anomalies on water cycle components and vegetation were further investigated over ENSO-sensitive sub-regions including Amazonia, Australia, southern Africa, and the South American Parana delta region. The ASWI component information linked the effect of drought and pluvial events on vegetation health to underlying changes in surface water inundation, soil moisture and atmospheric moisture deficits. The new satellite-based assessments reveal the global complexity of ENSO-related impacts on surface water storages, and the influence of these climate and hydrologic perturbations on ecosystem productivity.

Automated summary

Utilizing environmental metrics derived from satellite observations, this study quantified the global impact of ENSO events on surface wetting and drying anomalies, as well as vegetation health. The analysis revealed complex impacts on water distribution to plant communities, with vegetation showing varying sensitivity to drought and pluvial events. The intense 2015/2016 El Nino event coincided with strong latitudinal correspondence between ASWI and VHI, highlighting the intricate relationship between ENSO-related impacts and ecosystem productivity.