Atmospheric rivers are interesting phenomena. These regions of moisture traveling through the atmosphere and carrying more water than the Mississippi River at its mouth originate from tropical regions and flow through storms.
A new study published in the journal Nature Geoscience explains how, between 1997 and 2014, about half of the top 2 percent of the most extreme storm the world has faced were associated with atmospheric rivers.
These rivers can be 300 kilometers wide and thousands of kilometers long and can be found at altitudes between 1 and 2.5 kilometers. The authors of the study wrote that “Atmospheric rivers are associated with a doubling or more of the typical wind speed compared to all storm conditions, and a 50–100% increase in the wind and precipitation values for extreme events.”
Areas such as western Canada, northern Europe, New Zealand and southern South America can face these rivers for up to 35 days a year. Out of the 19 most damaging storms that hit Europe between 1979 and 2003, 14 were related to atmospheric river activity.
The study concludes “that landfalling atmospheric rivers can represent a significant hazard around the globe, because of their association with not only extreme precipitation, but also extreme winds.”
California suffered from the phenomena during this winter when atmospheric rivers soaked it up the state with lots of rainfall, ending the epic drought in the state but also causing havoc in lots of parts of California.
Jeff Zimmerman of the National Weather Service reports that “This has been a very active winter, atmospheric river-wise,” and that “We’ve probably had 10 or more … this winter.”
Aside from carrying the potential for floods, “they also come with potential for high impact winds and extremes that can produce hazardous conditions,” explains Duane Waliser, an atmospheric scientist and one of the authors of the study.
The phenomena could become more prominent due to climate changes. Waliser plans to find out if and how climate change affects atmospheric rivers and could it make them more frequent.