1In the United States, irrigation represents the largest consumptive use of freshwater and 2 accounts for approximately one-third of total water usage. Irrigation impacts soil moisture 3 and can ultimately influence clouds and precipitation through land-planetary boundary 4 layer (PBL) coupling processes. This study utilizes NASA's Land Information System (LIS) 5 and the NASA Unified Weather Research and Forecasting (NU-WRF) framework to 6 investigate the effects of drip, flood, and sprinkler irrigation methods on land-atmosphere 7 interactions, including land-PBL coupling and feedbacks at the local scale. Five-year 8 irrigated LIS spinups were used to initialize two-day, 1 km WRF forecasts over the Central 9Great Plains in a drier than normal (2006) and a wetter than normal year (2008). The 10 offline and coupled simulation results show that regional irrigation impacts are sensitive to 11 time, space and method, and that irrigation cools and moistens the surface over and 12 downwind of irrigated areas, ultimately resulting in both positive and negative feedbacks 13 on the PBL depending on the time of day and background climate conditions. Furthermore, 14 the results portray the importance of both irrigation method physics and correct 15 representation of several key components of land surface models including accurate and 16 timely land cover and crop type classification, phenology (greenness), and soil moisture 17 anomalies (through an LSM spinup) in coupled prediction models. 18 3

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Irrigation can influence weather and climate, but the magnitude, timing, and spatial extent of irrigation are poorly represented in models, as are the resulting impacts of irrigation on the coupled land‐atmosphere system. One way to improve irrigation representation in models is to assimilate soil moisture observations that reflect an irrigation signal to improve model states. Satellite remote sensing is a promising avenue for obtaining these needed observations on a routine basis, but to date, irrigation detection in passive microwave satellites has proven difficult. In this study, results show that the new enhanced soil moisture product from the Soil Moisture Active Passive satellite is able to capture irrigation signals over three semiarid regions in the western United States. This marks an advancement in Earth‐observing satellite skill and the ability to monitor human impacts on the water cycle.