Modeled changes to the Great Plains low-level jet under a realistic irrigation application

Area of Science:

• Atmospheric Science
• Meteorology
• Climate Modeling

Background:

• Low-level jets (LLJs) are crucial for moisture transport and convection in the Great Plains.
• Anthropogenic activities, like irrigation, can alter surface energy fluxes, influencing the planetary boundary layer (PBL) and LLJs.

Purpose of the Study:

• To investigate the effects of realistic irrigation on LLJ development across the Great Plains.
• To compare simulation results with and without a dynamic irrigation scheme.

Main Methods:

• Incorporated a dynamic irrigation scheme into the Weather Research and Forecasting (WRF) model.
• Conducted WRF simulations for the summer of 2012, a period of drought in the Great Plains, with and without the irrigation scheme.

Main Results:

• Simulations showed statistically significant increases in LLJ speeds with the irrigation scheme active.
• A decrease in mean jet core height (approx. 50 m) during overnight hours was observed with irrigation.
• A 5-10% increase in LLJ occurrence frequency over irrigated regions was noted, though not statistically significant.

Conclusions:

• Realistic irrigation schemes in climate models produce more nuanced changes to LLJs compared to simpler, less realistic methods.
• Accurate representation of human activities, such as irrigation, is essential for improving climate model predictions of atmospheric phenomena like LLJs.