Differential impacts of irrigation on precipitation across the United States

These data are used in "Differential impacts of irrigation on precipitation across the United States", Environmental Research Letters. Stefano Casirati¹, Paolo d’Odorico¹, Inez Fung¹, Andrea Molod², and Manuela Girotto¹¹Environmental Science and Policy Management, University of California, Berkeley, CA, USA;²Global Modeling and Assimilation Office, NASA Goddard Space Flight Center, Greenbelt, MD, USA; AbstractIrrigation is a major anthropogenic modification of the land surface that can influence regional precipitation patterns. Its effects vary across regions and seasons, yet previous studies show no consensus on whether irrigation enhances or suppresses rainfall. Using the NASA GEOS Earth System Model with a physically based irrigation module, we simulated irrigated and control scenarios to quantify irrigation-induced changes in precipitation and evapotranspiration across the contiguous United States. We quantify how irrigation drives land-atmosphere mechanisms underlying irrigation-induced changes in precipitation both regionally and seasonally. Focusing on key agricultural regions of the United States, we show that during summer, the Western United States shows negligible precipitation response despite irrigation rates reaching local maxima of ~100 mm month⁻¹; the Great Plains generally exhibits average precipitation increases of ~7 mm month⁻¹ in both irrigated and adjacent rainfed areas, though intensively irrigated zones may experience negligible or even slightly negative rainfall changes; and the Southeastern United States shows negligible or negative precipitation changes in irrigated areas, while rainfall increases by ~10 mm month⁻¹ downwind due to the spillover effect. In spring, lower irrigation rates promote local precipitation increases through enhanced evapotranspiration and moisture availability. These results demonstrate how irrigation redistributes precipitation across regions and seasons and underscore the importance of representing irrigation practices in Earth System Models. Description of the data and file structure This dataset contains seasonal aggregates (ensemble mean and ensemble standard deviation) derived from monthly output of simulations performed with the NASA GEOS Atmospheric General Circulation Model (AGCM). The provided files are in NetCDF-4 format and contain processed data subsetted over the continental United States (CONUS) region. File naming convention Each file follows the naming structure: USA_"Experiment"_seasonal_"Metric"_"Season".nc4 where: Experiment identifies the irrigation configuration: Control: simulations performed with the irrigation module deactivated. Irrig: simulations performed with the irrigation module activated. Difference: difference between irrigation and control simulations (Irrig − Control). Metric identifies the ensemble statistic: mean: ensemble mean. sd: ensemble standard deviation. Season identifies the seasonal aggregation period: DJF: December–January–February. MAM: March–April–May. JJA: June–July–August. SON: September–October–November. Dataset organization The dataset is provided in two compressed archives: 1. Seasonal_Statistics.zip This archive contains seasonal mean and standard deviation statistics for surface and near-surface variables: PRECTOT, IRRLAND, T2M, EVLAND, U2M, V2M, TS, QS The corresponding NetCDF-4 files contain two-dimensional spatial fields with latitude (lat) and longitude (lon) dimensions. 2. Seasonal_Statistics_Prog.zip This archive contains seasonal mean and standard deviation statistics for atmospheric profile variables provided on three pressure levels (lev: 850 hPa, 500 hPa, and 250 hPa): OMEGA, T, H, QV, U, V The corresponding NetCDF-4 files contain three-dimensional atmospheric fields with latitude (lat), longitude (lon), and pressure level (lev) dimensions. Variable glossary Variable: EVLANDDescription: Total land evapotranspirationUnits: kg m⁻² s⁻¹ Variable: HDescription: Geopotential heightUnits: m Variable: IRRLANDDescription: Total irrigation rateUnits: kg m⁻² s⁻¹ Variable: OMEGADescription: Downward vertical pressure velocityUnits: Pa s⁻¹ Variable: PRECTOTDescription: Total precipitationUnits: kg m⁻² s⁻¹ Variable: QSDescription: Surface specific humidityUnits: kg kg⁻¹ Variable: QVDescription: Specific humidityUnits: kg kg⁻¹ Variable: TDescription: Air temperatureUnits: K Variable: T2MDescription: 2-meter air temperatureUnits: K Variable: TSDescription: Surface temperatureUnits: K Variable: UDescription: Eastward wind componentUnits: m s⁻¹ Variable: U2MDescription: 2-meter eastward wind componentUnits: m s⁻¹ Variable: VDescription: Northward wind componentUnits: m s⁻¹ Variable: V2MDescription: 2-meter northward wind componentUnits: m s⁻¹