The three linked articles all discuss recent research findings about atmospheric river events. The first reference finds that global warming will increase the intensity of atmospheric river events along the U.S. West Coast:
Title: "70-year record shows long-term trend in atmospheric river activity along U.S. West Coast"
http://blogs.agu.org/geospace/2017/08/03/70-year-record-shows-long-term-trend-atmospheric-river-activity-along-u-s-west-coast/Extract: "The researchers found warmer oceans are associated with more intense atmospheric river activity, which leads to more extreme precipitation. Sea surface temperatures worldwide have increased by about 1 degree Fahrenheit (about 0.5 degrees Celsius) since the late 1940s as a result of climate change, and the Pacific Ocean has been warming at the same pace. Previous research has shown the warmer sea surface temperature patterns highlighted by this study are a result of global warming from human activity.
The authors also used the longer record to tease out other patterns in atmospheric river activity. Previous records of atmospheric river activity along the West coast extended only to the 1970s and only captured one complete phase of the Pacific Decadal Oscillation, a natural climate pattern with warm and cool phases appearing to last 20-30 years based on the current record.
Along with other patterns of climate variation, the Pacific Decadal Oscillation (PDO) has been shown by the new study to strongly affect atmospheric river activity. The effect of the PDO on atmospheric rivers is so far much larger than the effect of gradually warming oceans due to human activity, according to the new study."
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Title: "NASA estimates the global reach of atmospheric rivers"
https://phys.org/news/2017-11-nasa-global-atmospheric-rivers.htmlExtract: "A recent study by NASA and several partners has estimated, for the first time, the global impact of atmospheric rivers on floods and droughts, as well as the number of people affected by these atmospheric phenomena. "
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Title: "Research Roundup: Atmospheric Rivers”
https://earthobservatory.nasa.gov/blogs/earthmatters/2017/10/27/research-roundup-atmospheric-rivers/