Atmospheric river variability over the last millennium driven by annular modes: Part 3 (AR tags for ERA5)

Atmospheric rivers (ARs) are filamentary structures of intense water vapor transport commonly found in the extratropical atmosphere. ARs are a crucial component of the Earth’s general circulation: ARs account for up to 90% of poleward moisture transport and are a reliable (and sometimes extreme) source of precipitation for midlatitude coastal regions around the world. Although ARs operate primarily in the extratropics, how ARs respond to extratropical climate variability remains poorly understood. In this study, we use millennium-long climate model simulations to examine how annular modes of climate variability—the dominant mode of climate variability in the extratropics in both the Northern and Southern Hemispheres—affect ARs. We find that phases of the annular modes induce strong north–south displacements in AR activity, with up to ~20–25 mm/month associated changes in precipitation. These AR changes are also found in the observational record, indicating that our model results are r..., ,