Exploring climate-groundwater-wetland nexus in North America Prairie Pothole Region using convection-permitting simulations

Abstract:

Groundwater plays key roles in providing freshwater resources, regulating regional climate, and supporting wetland habitats for biodiversity. In particular, its interactions within the hydrological cycle act as a two-way buffer from seasonal climate variations, absorbing excessive drainage during wet seasons and supplying soil moisture during dry seasons. However, simulating groundwater and wetlands are challenging, because of lack of the presentation of the groundwater-soil moisture interaction in previous regional climate models. Also, the complex surface heterogeneity also requires high resolution simulations, which is computationally expensive. In this study, we conducted both offline and convection-permitting coupled climate-groundwater-wetland simulations to study their complex interactions. In the offline simulations, climate forcing from the convection-permitting CONUS-WRF simulations are used to drive Noah-MP LSM. Two dynamic groundwater options are used, one is the TOPMODEL-based within-grid groundwater redistribution scheme (run_opt=1) and the other one is the 2-D water table dynamics scheme with lateral flows (run_opt=5). The model simulated dynamic terrestrial water storage (TWS) and wetland saturated fraction (Fsat) were evaluated against global remote sensing products, Gravity Recovery and Climate Experiment (GRACE) and Global Inundation Extents from Multiple Satellites (GIEMS), respectively. For the coupled simulations, we conducted convection-permitting WRF-NoahMP simulations with these two dynamic groundwater options for three warm seasons (from April to September) in dry, normal, and wet years respectively. Results suggest that groundwater supply for soil moisture as well as surface moisture conditions is significant, especially with the lateral flow scheme. Its feedback to near surface temperature and precipitation is more dominant compared to previous coarse resolution modeling studies. These results highlight the importance of conducting high-resolution convection-permitting simulations for capturing groundwater and wetland dynamics with complex surface heterogeneity and its feedback to regional climate.