Advancing Atmospheric River science and inspiring future development of the Atmospheric River reconnaissance program

Over the last two decades, the important role of atmospheric rivers in many extreme precipitation and flood episodes in western North America, the western Pacific, Europe, New Zealand, and South America has become clear. These long and narrow features -- typically around 2,000 km in length and 800 km in width -- are often located ahead of the cold front within an extratropical cyclone and are characterized by strong horizontal water vapor flux. In fact, the moisture transported by ARs can be the equivalent of greater than 2 times the freshwater flux of the Amazon River. Furthermore, the precipitation associated with ARs is essential for many precipitation-sensitive midlatitude regions, where, for example, it can provide up to 50% of the annual precipitation in California, in Europe, and in Chile, and supply beneficial snowpack, which makes ARs crucial for water resources and supply.