Impacts of land–atmosphere coupling on regional rainfall and convection

Abstract

By analyzing rainfall events over four land–atmosphere coupling hotspot regions, the study assesses the need for adopting a dynamic coupling strength within the land surface model. The study aims to investigate the impacts of land–atmosphere coupling on mesoscale convection and rainfall over different hotspot regions. Impacts of land–atmosphere coupling are analyzed using Noah land model and Weather Research and Forecasting (WRF) model simulations over U.S. Southern Great Plains (SGP), Europe, northern India, and West Africa. The SGP stands out as a region of strong land–atmosphere coupling. While, over India and West Africa the default WRF model leads to too strong coupling effects. The results show improvements by adopting the dynamic coupling coefficient in simulating surface fluxes and resulting atmospheric state. For the four regions, the results indicate that the surface coupling coefficient does not affect the general location but could improve the intensity of the simulated precipitation. There is high uncertainty in land–atmosphere coupling and the results from this and prior studies need to be considered with caution. In particular, zones identified as coupling hotspots in climate studies and their coupling strength would likely change depending on the model formulations and coupling coefficient assigned. Results support the use of the dynamic coupling formulation for use in future studies but with a caution for use over complex terrains. Overall, these results highlight that evaluating and improving land–atmosphere coupling could potentially improve model performance across the globe.