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Publication Date
15 November 2022

Atmospheric River Lifecycle has Flavors

Subtitle
Atmospheric river lifecycles with different flavors show distinct lifecycle characteristics and landfall impacts.
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Image
The wind and moisture relation of North Pacific wintertime Atmospheric rivers. Embedded panel shows the wet ARs generally have more precipitation than windy ARs in one AR lifecycle.
Science

Atmospheric rivers (ARs) are long and narrow plumes in the atmosphere that transport water vapor from the tropics to high latitudes. ARs generally have strong wind and rich moisture, but the relative strength of wind and moisture can be different for individual ARs. This study divides the ARs into two flavors: windy ARs (stronger wind and less moisture) and wet ARs (weaker wind and more moisture), and compares the differences within.

Impact

Characterizing ARs into different “flavors” has great implications for different research topics. We show that different processes may act together in the wind and moisture environment to form ARs, and the dominant process may determine the AR flavors. Also, AR flavors can help to understand changes in ARs in the future climate. We demonstrate that ARs with different flavors can respond to climate change forcing to different extents.

Summary

Atmospheric rivers (ARs) are intensive poleward moisture transport events that are essential to the global hydrological cycle and are often linked to extreme weather events. We categorize the winter North Pacific ARs into two “flavors”: wind-dominated (windy ARs) and moisture-dominated (wet ARs), using 40 years of hourly data from ERA5 reanalysis. We compare the differences between windy ARs and wet ARs, including the lifecycle characteristics (such as genesis locations and changes of meteorological elements through the lifecycle), overall AR frequency, landfall impacts, and variability. Results show that windy ARs are more likely to occur in the midlatitudes and make landfall in British Columbia. Wet ARs are more active over the subtropics and more prevalent over the U.S. West Coast, especially in California. Windy ARs and wet ARs respond differently to climate variability like El Niño Southern Oscillation.

Point of Contact
Yang Zhou
Institution(s)
Climate and Ecosystem Sciences Division Lawrence Berkeley National Laboratory Berkeley California USA
Funding Program Area(s)
Additional Resources:
NERSC
Publication