Dataset and Analysis Code Supporting "Asymmetric Impacts of Supply- and Demand-Driven Flash Droughts on Leaf Senescence"

This repository contains the processed datasets and R scripts supporting the manuscript entitled “Asymmetric impacts of supply- and demand-driven flash droughts on leaf senescence.” The study investigates the asymmetric effects of supply-driven flash droughts, mainly associated with precipitation deficits, and demand-driven flash droughts, mainly associated with enhanced atmospheric evaporative demand, on vegetation leaf senescence across the Northern Hemisphere during 2001–2024. The repository includes two processed data files. dEOS_poly.csv contains satellite-derived phenological information based on the enhanced vegetation index (EVI) and solar-induced chlorophyll fluorescence (SIF). The term “EOS” used in the file name and scripts denotes the end-of-season phenological metric and corresponds to the leaf senescence date (LSD) used in the manuscript. SMrz_drought_events_mean_environment_anomaly.csv contains identified root-zone soil-moisture flash drought events and their associated mean environmental anomalies. These data were used to classify flash droughts into supply- and demand-driven types and to characterize their hydroclimatic conditions and vegetation responses. Because of repository file-size limitations, this file contains a randomly selected 10% sample of all flash drought events used in the study. The sampling was conducted solely to reduce file size and preserve the variable structure and representative range of the complete dataset. The accompanying R scripts perform the principal data processing, statistical analyses, and visualization procedures used in the study. 01_FD_detection.R identifies flash drought events from root-zone soil-moisture percentiles and calculates drought characteristics. 02_FD_environment_anomaly.R calculates environmental anomalies during flash drought events and supports the classification of supply- and demand-driven flash droughts. 03_phenology_extraction.R extracts vegetation phenological metrics from satellite-derived EVI and SIF time series. 04_phenology_anomaly_nonFD_baseline.R calculates phenological anomalies relative to years without flash droughts. 05_RF_SHAP_analysis.R conducts random forest modeling and SHAP analysis to identify the climatic and biotic controls of leaf senescence responses. 06_SEM_analysis.R performs structural equation modeling to examine the pathways through which the two flash drought types regulate leaf senescence. 07_phenology_response_significance.R evaluates the significance of phenological responses to flash droughts. 08_visualization_analysis.R generates the principal figures and statistical visualizations, and 09_visualization_SHAP_analysis.R produces the SHAP importance and dependence plots. The original satellite, reanalysis, and ancillary datasets are not redistributed in this repository. They are publicly available from their respective data providers, as documented in the associated manuscript. The deposited scripts provide the workflow used to generate the complete processed dataset. The 10% event sample is provided to demonstrate the data structure and facilitate testing of the analytical workflow; analyses and numerical results reported in the manuscript were based on the complete dataset.