The Effect of Dynamic Root Water Uptake on Land-Atmosphere Interactions Over the Southern Great Plains

Description

Most state-of-the-art land surface models underestimate ecosystem resiliency during drought conditions, resulting in evapotranspiration smaller than observations under water stress conditions. Recent studies have shown that direct root water uptake from the capillary fringe and groundwater could help obtain transpiration rates greater than precipitation by a factor of 10 in hyper-arid conditions. Here, we aim to address this issue by explicitly representing plant water storage in a newly developed dynamic root water uptake scheme in the WRF model and investigate its impact on land-atmosphere interactions. Observations from the Oklahoma Mesonet and the ARM observation sites are used to evaluate the model's performance. When compared with the reference datasets, the simulated spatial distribution of sensible and latent fluxes is significantly improved over the Great Plains of the United States. The time series of soil moisture simulated by the dynamic root scheme also shows significant improvement compared to the default static root scheme. Additionally, we will discuss the role of the dynamic root scheme in addressing the warm-and-dry bias observed over the central United States.