Detection Uncertainty Matters for Understanding Atmospheric Rivers

Both initial tier 2 experiments are focused on understanding the effects of climate change on AR characteristics, with the C20C+ experiment focusing on a set of high-resolution atmosphere-only simulations, and the CMIP5/6 experiment focusing on a multimodel collection of fully coupled simulations from the Coupled Model Intercomparison Project. Key gaps and research priorities Basic research on AR life cycle. * Gap: The physical drivers of AR genesis, development, and dissipation are not completely understood, and this lack of understanding impedes our ability to constrain the quantitative definition, detection, and tracking of ARs. * Recommendation: There is a need for more basic research on the dynamics and life cycle of ARs. Ideally, “flavored” AR tracking methods could incorporate connections to surface precipitation, interactions with synoptic-scale baroclinicity, and interactions with other phenomena such as tropical cyclones and jet streams. Despite the focus of the discussion on existing uncertainties in AR detection techniques and impacts on AR science, the group found a cause for cautious optimism: analogous to different physics parameterizations in climate models, different AR algorithms were developed with different goals in mind, and thus may each have distinct applications.