When rivers reach the sky
BY KAI-CHIH TSENG AND NAT JOHNSON
PUBLISHED FEBRUARY 24, 2022
COMMENTS: 7
Guest co-author Dr. Kai-Chih Tseng is a postdoctoral research scientist at Princeton University and the NOAA Geophysical Fluid Dynamics Laboratory who is an expert on climate variability and prediction, including the study of atmospheric rivers. In the summer of 2022, Dr. Tseng will begin an assistant professor position in the Department of Atmospheric Science at National Taiwan University.
This past December, a mind-boggling 18 feet of snowfall fell in the California Sierra Nevada Mountains! How does so much snow fall in one place in such a short period of time? One of the primary phenomena responsible for such extreme rain and snowfall, particularly in regions like the western U.S., is the atmospheric river. Like their terrestrial counterparts, atmospheric rivers carry tremendous amounts of water over thousands of miles. These aerial versions, however, often bring both severe disruption and great benefit through the heavy rain and mountain snows that they produce. In this blog post, we will give you a brief primer on atmospheric rivers and (of course!) explain how they are affected by ENSO (El Niño-Southern Oscillation).
Flying Mississippis
Natural-color satellite image of a cloud plume reaching form tropics to US West Coast
Satellite image taken on October 24, 2021. A powerful storm off the Pacific Northwest coast brought an intense atmospheric river to the San Francisco Bay region of California. NASA MODIS/TERRA satellite image taken from NASA Worldview.
Atmospheric rivers are long, narrow corridors of moisture-laden air extending from the tropics to higher latitudes. They can produce heavy rain and snowfall in short periods of time, especially when the air is lifted over high terrain, cooling the air and condensing the moisture into droplets, like wringing out an atmospheric sponge. When you see these impressively long features on satellite imagery, it’s no wonder that they are compared to rivers. In fact, an average atmospheric river carries 25 times the amount of water as the Mississippi River!
https://www.climate.gov/news-features/blogs/enso/when-rivers-reach-sky
