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By Sally Younger
March 16, 2023
Dark clouds roil the sky above Pasadena, California, during an atmospheric river event. A series of nine such storms delivered record amounts of rain and snow to the state and caused multiple deaths between late 2022 and January 2023. Additional atmospheric rivers have inundated California since. Credit: NASA/JPL-Caltech
Like hurricane categories, a scale for atmospheric river storm severity could help communities around the globe compare and prepare.
Atmospheric rivers – vast airborne corridors of water vapor flowing from Earth’s tropics toward higher latitudes – can steer much-needed rain to parched lands. But in extreme form, they can also cause destruction and loss of life, as recently occurred in parts of California. Their effects, both hazardous and beneficial, are felt globally.
A new study using NASA data shows that a recently developed rating system can provide a consistent global benchmark for tracking these “rivers in the sky.” Research into atmospheric rivers has largely focused on the west coasts of North America and Europe. The new findings help expand our understanding of how these storms arise, evolve, and impact communities all over the world. In addition, the ratings could help meteorologists better warn people to plan for them.
View: https://youtu.be/3cv893sW7to
An atmospheric river system that traveled across the Pacific Ocean in 2017 is captured here in satellite imagery by NASA’s AIRS instrument. Scientists are working to understand how these powerful storms impact regions of the world beyond western North America and Europe.
Credit: NASA/JPL-Caltech
In the new study, scientists built a database of global atmospheric river events from 1980 to 2020, using a computer algorithm to automatically identify tens of thousands of the events in the Modern-Era Retrospective analysis for Research and Applications, version 2 (MERRA-2), a NASA re-analysis of historical atmospheric observations. To rank the events, the study authors then applied the atmospheric river scale, which is based on a storm’s expected duration and maximum rate of water vapor transport.
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Across the 40 years studied, higher-ranked storms lasted longer and traveled farther than lower-ranked storms. Mean travel distance was found to be about 400 miles (650 kilometers) with AR 1 and about 2,900 miles (4,700 kilometers) with AR 5, while mean lifetime was about 17 hours for AR 1 and 110 hours for AR 5. Higher-ranked storms (AR 4 and AR 5) were less common and tended to begin their life cycle closer to the tropics while ending in colder, higher-latitude regions.
Additionally, the scientists detected an increase in atmospheric river frequency during strong El Niño years.
“The current study helps to highlight the global reach of atmospheric rivers, as well as their possible origins, including in less-explored regions where the environmental conditions and societal impacts could be different from where we currently live [in the United States],” said lead author Bin Guan, a scientist at the Joint Institute for Regional Earth System Science and Engineering (JIFRESSE). The institute is a collaboration between University of California, Los Angeles and NASA’s Jet Propulsion Laboratory in Southern California.
A uniform scale can be useful for diagnosing atmospheric rivers in an era of instant communications, the scientists said. A key advantage is that the ratings minimize possible confusion when comparing the same meteorological phenomenon across languages and cultures. They noted this has not been the case for some more familiar weather events, such as tropical cyclones, which have been categorized using different thresholds in different regions.
Guan and colleagues said that taking the next step and translating the scale into region-specific impacts will require more research that takes into consideration local characteristics. They noted that many factors, from geography to socioeconomics, can influence how a storm is perceived by those who weather it.
News Media Contact
Jane J. Lee / Andrew Wang
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-0307 / 626-379-6874
jane.j.lee@jpl.nasa.gov / andrew.wang@jpl.nasa.gov
See: https://www.jpl.nasa.gov/news/ranking-atmospheric-rivers-new-study-finds-world-of-potential?utm_source=iContact&utm_medium=email&utm_campaign=nasajpl&utm_content=daily20230316-1
Atmospheric rivers of humid moisture laden air are a critical element in the in the global water cycle and are closely tied to both the levels within the reservoir systems supplying drinking water to metropolitan areas and, on the opposite side of the coin, they create flood risks due to excessive precipitation, especially in the western United States. While atmospheric rivers are responsible for great quantities of rain that can produce flooding, they also contribute to beneficial increases in the snowpack which provides water runoff for the irrigation of crops as it melts over time.
Hartmann352
March 16, 2023
Dark clouds roil the sky above Pasadena, California, during an atmospheric river event. A series of nine such storms delivered record amounts of rain and snow to the state and caused multiple deaths between late 2022 and January 2023. Additional atmospheric rivers have inundated California since. Credit: NASA/JPL-Caltech
Like hurricane categories, a scale for atmospheric river storm severity could help communities around the globe compare and prepare.
Atmospheric rivers – vast airborne corridors of water vapor flowing from Earth’s tropics toward higher latitudes – can steer much-needed rain to parched lands. But in extreme form, they can also cause destruction and loss of life, as recently occurred in parts of California. Their effects, both hazardous and beneficial, are felt globally.
A new study using NASA data shows that a recently developed rating system can provide a consistent global benchmark for tracking these “rivers in the sky.” Research into atmospheric rivers has largely focused on the west coasts of North America and Europe. The new findings help expand our understanding of how these storms arise, evolve, and impact communities all over the world. In addition, the ratings could help meteorologists better warn people to plan for them.
An atmospheric river system that traveled across the Pacific Ocean in 2017 is captured here in satellite imagery by NASA’s AIRS instrument. Scientists are working to understand how these powerful storms impact regions of the world beyond western North America and Europe.
Credit: NASA/JPL-Caltech
In the new study, scientists built a database of global atmospheric river events from 1980 to 2020, using a computer algorithm to automatically identify tens of thousands of the events in the Modern-Era Retrospective analysis for Research and Applications, version 2 (MERRA-2), a NASA re-analysis of historical atmospheric observations. To rank the events, the study authors then applied the atmospheric river scale, which is based on a storm’s expected duration and maximum rate of water vapor transport.
z
Across the 40 years studied, higher-ranked storms lasted longer and traveled farther than lower-ranked storms. Mean travel distance was found to be about 400 miles (650 kilometers) with AR 1 and about 2,900 miles (4,700 kilometers) with AR 5, while mean lifetime was about 17 hours for AR 1 and 110 hours for AR 5. Higher-ranked storms (AR 4 and AR 5) were less common and tended to begin their life cycle closer to the tropics while ending in colder, higher-latitude regions.
Additionally, the scientists detected an increase in atmospheric river frequency during strong El Niño years.
“The current study helps to highlight the global reach of atmospheric rivers, as well as their possible origins, including in less-explored regions where the environmental conditions and societal impacts could be different from where we currently live [in the United States],” said lead author Bin Guan, a scientist at the Joint Institute for Regional Earth System Science and Engineering (JIFRESSE). The institute is a collaboration between University of California, Los Angeles and NASA’s Jet Propulsion Laboratory in Southern California.
A uniform scale can be useful for diagnosing atmospheric rivers in an era of instant communications, the scientists said. A key advantage is that the ratings minimize possible confusion when comparing the same meteorological phenomenon across languages and cultures. They noted this has not been the case for some more familiar weather events, such as tropical cyclones, which have been categorized using different thresholds in different regions.
Guan and colleagues said that taking the next step and translating the scale into region-specific impacts will require more research that takes into consideration local characteristics. They noted that many factors, from geography to socioeconomics, can influence how a storm is perceived by those who weather it.
News Media Contact
Jane J. Lee / Andrew Wang
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-0307 / 626-379-6874
jane.j.lee@jpl.nasa.gov / andrew.wang@jpl.nasa.gov
See: https://www.jpl.nasa.gov/news/ranking-atmospheric-rivers-new-study-finds-world-of-potential?utm_source=iContact&utm_medium=email&utm_campaign=nasajpl&utm_content=daily20230316-1
Atmospheric rivers of humid moisture laden air are a critical element in the in the global water cycle and are closely tied to both the levels within the reservoir systems supplying drinking water to metropolitan areas and, on the opposite side of the coin, they create flood risks due to excessive precipitation, especially in the western United States. While atmospheric rivers are responsible for great quantities of rain that can produce flooding, they also contribute to beneficial increases in the snowpack which provides water runoff for the irrigation of crops as it melts over time.
Hartmann352
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