Fig. 2: Estimated effects of climate indices on winter wheat yields relative to the average yield.
From: U.S. winter wheat yield loss attributed to compound hot-dry-windy events
a The yield effects are expressed as a percent of area-weighted average yield (grand average = 2.4 t ha−1) across our study domain per standard unit of climate indices (Supplementary Table 2). One standard unit of climate indices in their distributions across the study domain is 14.77 days for FrezPT-JT, 0.89 days for FrezJT-HD, 0.35 °C days for EDDJT-HD, 2.81 °C days for EDDHD-MT, and 9.03 h for HDW. Frez stands for freezing; EDD stands for extreme degree days; HDW stands for hot-dry-windy events. PT-JT is the planting to jointing stage; JT-HD is the jointing to heading stage; HD-MT is the heading to maturity stage. b The percent change in yield as a function of the cumulative precipitation (Prcp) by growth stages. The shaded bands represent the one adjusted standard error of regression in the original units (mm). Histograms show the frequency of county-year accumulated precipitation for specific phenological stages. The three vertical lines represent the 95th percentile of Prcp for corresponding phenological stages. c Yield effects of climate indices including individual extreme events (hot, H; dry, D; wind, W), bivariate events (hot-dry, H&D; hot-windy, H&W; dry-windy, D&W), and trivariate compound events (hot-dry-windy, HDW). d Yield sensitivity to HDW (bars) and frequency of county-year HDW (histograms) during early, middle, and last sub-stages from HD to MT stage. The error bars indicate one clustering standard error (SE) and asterisks denote the significance (**p ≤ 0.05); NS, not significant (p > 0.05).
