Soil Moisture-Evapotranspiration coupling

This module computes the correlation between surface soil moisture (SM; top-10CM) and evapotranspiration (ET), at the interannual time scale, using summertime-mean values (JJA in the Northern Hemisphere, DJF in the Southern Hemisphere). Positive correlations indicate that SM controls ET variations. Negative correlations indicate that ET is ernergy-limited (by radiation and temperature). The degree of coupling between SM and ET depends on how wet the local climate is; thus differences in precipitation between model and observations (independent, in first approximation, from the surface) induce differences in SM-ET coupling. Across CMIP5 models, the degree of SM-ET coupling is closely correlated with the amount of summertime rainfall; using this relationship (see Berg and Sheffield 2018, Figure 3), we correct the estimate of SM-ET coupling for the model by accounting for differences in summertime precipitation. In other words, the Pr-corrected estimate of SM-ET coupling is an estimate of the coupling that would be if precipitation in the model was equal to observed rainfall.

Soil Moisture-EvapoTranspiration coupling CM4_historical_LONG OBS (GLEAM) Model-OBS
Mean summertime Pr plot plot plot
SM-ET correlation plot plot plot
SM-ET correlation, with Pr correction plot plot