Global Atmospheric Rivers (Historic and Future)

Atmospheric rivers (ARs) are narrow jets of integrated water vapor transport that are important for the global water cycle, and also have large impacts on local weather and regional hydrology. Uniformly-weighted multi-model averages have been used to describe how ARs will change in the future, but this type of estimate does not consider skill or independence of the climate models of interest. Here, we utilize information from various model averaging approaches to evaluate 21 global climate models from the Coupled Model Intercomparison Project Phase 5 (CMIP5). Model ensemble weighting strategies based on atmospheric river model independence and performance skill relative to reanalysis data (ERA-Interim) result in lower uncertainties in the future estimates compared to the equal weighting strategy. These weighted models show that the frequency of ARs is expected to increase by the end of the century, with high certainty, by ~50% on average globally.