Evaluating hydrological processes in the C ommunity A tmosphere M odel V ersion 5 ( C AM5) using stable isotope ratios of water Journal of Advances in Modeling Earth Systems

Water isotope-enabled climate and earth system models are able to directly simulate paleocli- mate proxy records to aid in climate reconstruction. A less used major advantage is that water isotopo- logues provide an independent constraint on many atmospheric and hydrologic processes, allowing the model to be developed and tuned in a more physically accurate way. This paper describes the new isotope- enabled CAM5 model, including its isotopic physics routines, and its ability to simulate the modern distribu- tion of water isotopologues in vapor and precipitation. It is found that the model has a negative isotopic bias in precipitation. This bias is partially attributed to model overestimates of deep convection, particularly