The Wet and Windy Extremes of Landfalling Atmospheric Rivers

Atmospheric Rivers (ARs) are characterized by long, narrow filaments of high integrated water vapor transport (IVT), representing a synergistic combination of water vapor and wind.  Their influence on weather/climate extremes has primarily been investigated from a hydrological perspective, namely their profound influence on precipitation extremes and flooding and in only a limited number of regions.  Here we examine the association of ARs with the occurrence of precipitation and near surface wind extremes across the globe.  We show that ARs account for up to 50% or more of the top 10% of the precipitation and wind extremes across most mid-latitude regions.  We show that landfalling ARs are associated with a sizeable fraction of extreme wind and precipitation events over a large portion of the world’s coastlines, including historical peak events.  Examination of the AR influences on joint histograms of precipitation and wind for regions strongly affected by ARs (i.e. western N. America, western Europe, southern S. America, and New Zealand) illustrates that AR conditions have a profound impact on near surface wind and precipitation, with a doubling or tripling of typical values found for AR conditions relative to all precipitating storm conditions.  These results underscore the hazardous nature of landfalling AR events by quantifying their association with extreme wind conditions in addition to extreme precipitation.