Incorporating irrigation effects into high-resolution daily land evaporation estimates over the Iberian Peninsula

Abstract. Land evaporation (E) links the water, energy, and carbon cycles and plays a central role in agriculture, water management, and land–climate interactions. However, estimating E at high spatial and temporal resolution remains challenging, especially in irrigated regions. This study presents a novel framework to generate daily 1 km E estimates for 2018–2022 over the Iberian Peninsula by explicitly representing irrigation in the recently released Global Land Evaporation Amsterdam Model version 4 (GLEAM4). To this end, high-resolution (1 km) meteorological forcing is combined with Sentinel-1 soil moisture and ancillary information on irrigated extent and satellite-based crop phenology. Our method constrains E below potential evaporation (E_p) even in irrigated land, leveraging observational data of vapour pressure deficit, air temperature, vegetation optical depth, leaf area index, wind speed, and shortwave radiation, which allows irrigated crops to respond realistically to diverse sources of vegetation stress, rather than assuming E_p rates. Results reveal increases in E over irrigated areas of up to 450 mm yr^-1 when irrigation is explicitly considered, with spatial patterns consistent with independent irrigation estimates. Evaluation against eddy-covariance measurements demonstrates marked improvements at two irrigated sites in the Iberian Peninsula, with increases in daily Kling-Gupta Efficiency (KGE) compared to simulations without irrigation of 0.40 and 0.70, respectively. The approach is also relatively robust to false positives in the irrigation mask owing to the fractional vegetation structure of GLEAM4. Overall, the resulting high-resolution E dataset provides a realistic representation of irrigation practices and supports applications in both agricultural management and regional water-resource assessments. The approach will be extended to global scales through integration into future GLEAM releases.