Collaborative Research: Improving Process-Level Understanding of Surface-Atmosphere Interactions Leading to Convection Initiation in the Central United States

Soil moisture is important for the climate system because it controls evaporation, transpiration, and energy movement from the land to the atmosphere. Through these mechanisms, soil moisture can influence the timing and intensity of precipitation at daily to seasonal timescales. However, there is a lack of scientific consensus on the sign, strength, and overall importance of soil moisture-precipitation feedbacks.

This project will improve our understanding of the land and atmosphere processes that are important to convection initiation and precipitation during the warm season (May to September) in the central United States. The knowledge gained from this project will be used to improve the accuracy of simulations in operational weather and climate models. The project will provide undergraduate students, a graduate student, and postdoctoral researchers with training in research, science communication, and public outreach.

This project will assess the nature and strength of soil moisture feedbacks on convective precipitation in the central United States using a coupled observation-modeling framework to examine the physical processes linking the soil and boundary layer atmosphere. The objectives of the project are to: (1) evaluate whether convection occurs preferentially over wet or dry soils in the central United States, (2) quantify the influence of soil moisture on convection and precipitation using process-based metrics and high quality land and atmosphere observations, and (3) evaluate the response of convection and precipitation to changes in soil moisture conditions using the Weather Research and Forecast (WRF) model.

This project will utilize soil moisture observations from the National Coordinated Soil Moisture Monitoring Network and hundreds of thousands of convection events identified by the ThOR algorithm. This combination of in situ observations and the immense sample size of convective events provides an unprecedented opportunity to evaluate soil moisture – precipitation feedbacks.

The results of this study will lead to improvements in the parameterization schemes that are used in weather and climate models. This study focuses on a region that has the densest land-surface and boundary layer observations, but the process-based understanding of land-atmosphere interactions and their role in modulating the climate is readily transferable to other regions around the world.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.