Fig. 2: Phase diagram for categorizing land–atmosphere coupling regimes for six compound drought-heatwave events.
From: Variations in land-atmosphere coupling during drought-heatwave events
Scatter plot illustrates the temporal correlation coefficients between SManom and LHFanom (R(SManom, LHFanom); abscissa) and TMAXanom and LHFanom (R(TMAXanom, LHFanom; ordinate). Temporal correlations were calculated within a 31-day time window (see lead-lag time series in Fig. 1c). Each dot represents a single grid cell within extreme heat regions (non-hatched areas in Fig. 1a), based on the reference data. Only grid cells with R(SManom, TMAXanom) < −0.5 and p < 0.05 are colored; other grid cells are shown as x-shape markers without shading. Dot colors indicate kernel density with a bandwidth of 0.1 (shaded), and contour lines represent a kernel density of 0.5 derived from GLDAS (blue), ERA5-Land (orange), and GLEAM (yellow). Contour lines were calculated based on the same criteria as the colored dots. Each subplot is divided into seven coupling regimes (Regime I–Regime VII) based on the two values of correlation coefficients, indicated as boxes. Percentage values at the bottom of each box region represent the proportion of grid cells within that regime relative to the total number of grid cells. The proportions of grid cells not included in the coupling regimes are represented as black labels in the bottom left. Gray labels indicate the percentage values of uncolored markers.
