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Abstract The evaporation model for water isotopes proposed by Craig and Gordon (1965,https://books.google.co.in/books?id=6wIKAQAAIAAJ) is used in most isotope‐enabled atmospheric models for the parameterization of nonequilibrium fractionation during evaporation from the ocean. In this model, one of the most uncertain parameters is the nonequilibrium fractionation factor . Many isotope models use the formulation of Merlivat and Jouzel (1979,https://doi.org/10.1029/jc084ic08p05029), which parameterizes as a function of wind speed and distinguishes between a smooth and a rough regime to account for the effect of ocean waves. The resulting discontinuity in between smooth and rough regimes has been disputed by several empirical studies. Here, we present a new approach to parameterizing by explicitly accounting for the influence of wave drag on the momentum flux near the surface. Following Cifuentes‐Lorenzen et al. (2018,https://doi.org/10.1007/s10546‐018‐0376‐0), we add a third wave‐induced component to the total momentum flux, in addition to the viscous and turbulent components, and extend the definition of the eddy viscosity to account for the momentum flux due to waves and turbulent dissipation near the surface. The new scheme predicts a slight decrease of with wind speed, similar to the smooth‐regime parameterization of Merlivat and Jouzel (1979,https://doi.org/10.1029/jc084ic08p05029). This new parameterization is incorporated into the isotope‐enabled Community Atmosphere Model, where it improves the correlation of simulated and measured vapor deuterium excess relative to the default version and a version with constant , suggesting that it may be used as a valid representation of fractionation during evaporation from the ocean in future isotope models. 

Abstract The Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) was a yearlong expedition supported by the icebreaker R/V Polarstern , following the Transpolar Drift from October 2019 to October 2020. The campaign documented an annual cycle of physical, biological, and chemical processes impacting the atmosphere-ice-ocean system. Of central importance were measurements of the thermodynamic and dynamic evolution of the sea ice. A multi-agency international team led by the University of Colorado/CIRES and NOAA-PSL observed meteorology and surface-atmosphere energy exchanges, including radiation; turbulent momentum flux; turbulent latent and sensible heat flux; and snow conductive flux. There were four stations on the ice, a 10 m micrometeorological tower paired with a 23/30 m mast and radiation station and three autonomous Atmospheric Surface Flux Stations. Collectively, the four stations acquired ~928 days of data. This manuscript documents the acquisition and post-processing of those measurements and provides a guide for researchers to access and use the data products.