Fig. 1: Pre-season drought thresholds triggering an earlier DFS (PDT-DFS) based on both satellite-derived and site-level ground datasets.

a–d Spatial patterns of the PDT-DFS based on the satellite-derived dataset for DFS from the <10% quantile to the <40% quantile, respectively. Bar charts in a–d represent the density distribution of the spatial data, with the vertical dashed line indicating the median value of the threshold range. P in a–d represents the percentage of land area occupied by the regions with an identified PDT-DFS. M in a–d represents the mean value of the PDT-DFS. e Mean value of the PDT-DFS across different biomes based on the satellite-derived dataset. Letters on the vertical axis in e represent abbreviations of different biome names, with their full names provided in Supplementary Table S1. The longitudinal axes of ≤ DFS^10th, ≤ DFS^20th, ≤ DFS^30th, and ≤ DFS^40th in e represent DFS from the <10% to <40% quantiles, respectively. e The statistical significance across different DFS quantiles was determined using a one-way ANOVA. “Not Diff” indicates no statistically significant difference in PDT-DFS between any two biomes (p  >  0.01). f PDT-DFS based on site-level ground dataset. The lower dashed line in the box plot represents the 25^th percentile; upper dashed line represents the 75^th percentile; black line inside the box indicates the median value; the points on the box represent the PDT-DFS of each site-level ground dataset. M represents the average value in each box plot, and N represents the number of points in each box plot. The longitudinal axes of SPEI^10th, SPEI^20th, SPEI^30th, and SPEI^40th in f represent DFS from the <10% to <40% quantiles, respectively. The statistical significance across different DFS quantiles was determined using a one-way ANOVA. g Pearson correlation coefficients of PDT-DFS between satellite-derived and site-level ground datasets were calculated. The statistical significance of the correlation coefficients was assessed using a two-tailed t-test. No adjustments for multiple comparisons were made. Source data are provided as a Source Data file.