Abstract:
Atmospheric rivers (ARs) are often referred to as “rivers in the sky”. Rivers transport huge amounts of fresh water across large distances, they are longer than they are wide, and ultimately, currents drive their direction and speed. They are essential to regional climates, both midlatitude and polar, by supplying water to local communities. Atmospheric rivers, unlike terrestrial rivers, live in the troposphere and produce precipitation that typically deepen the snowpack, replenish groundwater, and define regional climate. Quantifying when, where, and how (and in what form) the water arrives, are essential questions for resource managers and community leaders. These questions become even more important for long term planning, and must include uncertainty estimates. With each progressive timescale (weather, seasonal, decadal, multi-century), characterizing and quantifying ARs in the context of climate, becomes increasingly difficult as the base-state changes. In this seminar, I will discuss uncertainty in atmospheric river definitions across timescales drawing on 8 years of community research and “lessons learned” from ARTMIP (Atmospheric River Tracking Method Intercomparison Project). Ultimately, there is no “one size fits all” definition of an AR, and for climate research, the definition is driven by the science question and region of interest.