Project goal: the project goal is to help guide the development and analysis of the unified forecast system (UFS) by adopting the latest stable water isotopes (SWI) modeling and observational…

Project goal: the project goal is to help guide the development and analysis of the unified forecast system (UFS) by adopting the latest stable water isotopes (SWI) modeling and observational capabilities, with special focus on precipitation and hydrological processes. Problem/opportunity statement: isotopic signals contain valuable information about atmospheric processes and the water cycle across time scales, from weather to climate. Recent development of innovative measurement techniques has produced SWI observations from ground, aircrafts, ships, and space. Enhancing observational capabilities, in turn, enable the scientific community to use these novel observations for process-level study, model evaluation, and data assimilation. Methodology/activities to be performed: this research will implement an innovative hydrometeorological diagnostic, i.e., stable water isotopes in liquid and vapor phases, in the UFS atmosphere and land model. We will investigate hydrological processes and extreme precipitation characteristics through isotope-enabled simulations and model-data comparison. Primary project products/outputs: the primary project products/outputs include: (i) swienabled UFS model, (II) SWI-enabled diagnostics and evaluation, and (III) SWI research in hydrological processes. The research results will be disseminated via peer-reviewed journal publications and conference presentations. The associated computer codes will be deposited in the UFS community code repository. Expected results, outcomes, and benefits: the project outcomes of incorporating water isotopic modeling and observational capabilities into the UFS system include: (i) isotopic measurements are distinct from other conventional measurements and could provide new and independent observational constraints on model parameterizations; (II) the evaluation of water isotopic composition in UFS against observations could provide process-oriented evaluation of model biases; and (III) water isotopic composition could be used to trace component-to-component interactions, i.e., fluxes among ocean, atmosphere, land hydrology, land ICE, and sea ICE. This project will lay the groundwork for an isotope-enabled UFS-based earth prediction system. Intended beneficiaries and recipients: recipients of the project outcomes will include the UFS communities from the academic to operational centers (e.g., NOAA/NWS/ncep). 2 page 12