In the new study, scientists constructed a database of international atmospheric river events from 1980 to 2020, working with a laptop or computer algorithm to automatically recognize tens of thousands of the events in the Contemporary-Era Retrospective evaluation for Study and Applications, version two (MERRA-two), a NASA re-evaluation of historical atmospheric observations. To rank the events, the study authors then applied the atmospheric river scale, which is primarily based on a storm’s anticipated duration and maximum price of water vapor transport.

Across the 40 years studied, larger-ranked storms lasted longer and traveled farther than reduce-ranked storms. Imply travel distance was identified to be about 400 miles (650 kilometers) with AR 1 and about two,900 miles (four,700 kilometers) with AR five, although imply lifetime was about 17 hours for AR 1 and 110 hours for AR five. Larger-ranked storms (AR four and AR five) had been much less prevalent and tended to start their life cycle closer to the tropics although ending in colder, larger-latitude regions.

Also, the scientists detected an improve in atmospheric river frequency in the course of sturdy El Niño years.