Fig. 6: Dependences of urban net ecosystem exchange (dNEE_u) on temperatures and soil water content in CONUS.

a Dependence of dNEE_u on the change of 2-meter air temperature (dT_2m). b On the change of soil temperature (dT_soil). c On the change of soil water content (dSWC). The background scatters in (a–c) show relation in all urban cells from the model. The cyan solid circles show the average over 20 major cities in CONUS (see Fig. 2e for city number). The red dashed lines show the linear regression of the background scatters: a dNEE_u = −0.57 dT_2m −0.08, R² = 0.02, p < 0.0001; b dNEE_u = −0.60 dT_soil −1.87, R² = 0.48, p < 0.0001; c dNEE_u = 15.59 dSWC −0.72, R² = 0.68, p < 0.0001. The dark blue dashed lines show the linear regression over the 20 cities: a dNEE_u = −4.15 dT_2m −1.02, R² = 0.41, p = 0.0034; b dNEE_u = −0.71 dT_soil −1.87, R² = 0.65, p < 0.0001; c dNEE_u = 14.62 dSWC −0.75, R² = 0.79, p < 0.0001. In a City 3-Los Angeles, CA is excluded as an outlier. All other regressions use all data. p-values indicate the significance of the regression coefficient. The histograms above and on the right show the distributions of dT_2m, dT_soil, dSWC, and dNEE_u, respectively.