Authors: Mohamed Ayache, Jean-Claude Dutay, Kazuyo Tachikawa, Gilles Ramstein, Laurent Li, Thomas Arsouze, Camille Risi, Anne Mouchet, Laurence Vidal, and Catherine Jeandel

Our present knowledge of ocean ventilation relies on the distributions of hydrographic tracers such as oxygen and neodymium; (i) the oxygen isotopic composition (δ¹⁸O) of ocean water varies as a function of the evaporation–precipitation balance and water mass mixing. (ii) the Nd isotopic composition (ε_Nd) is one of the most useful tracers to fingerprint water mass provenance. We have implemented these proxies in the high-resolution regional modeling platform NEMO/MED12/PISCES. This work highlights that the exchange with the margins is the main source of Nd, and that the impact of river discharge on [Nd] is localized near the mouths of the main rivers. In contrast with the global ocean, the atmospheric dust input has a basin-wide influence, and improves the agreement of simulated [Nd] with field data in the Mediterranean Sea. We use the same high-resolution model to simulate the δ¹⁸O distribution for the first time in this basin. Atmospheric hydrologic fluxes (evaporation and precipitation, and their isotopic content) are provided by the isotope-enabled atmospheric LMDZ model. A reasonable east–west gradients of δ¹⁸O is simulated by the model, which separates the less-evaporated and more-productive western basins from the more-evaporated and less-productive eastern basin. The knowledge of the present-day variability of the isotopic composition of the Mediterranean waters should help further studies dedicated to Mediterranean paleoceanography.