As summer continues to bring dry conditions to the Rogue basin, we are dreaming of heavy rains and flowing streams that are characteristic of a Pacific Northwest winter and spring. As it happens, I was visiting the Midwest earlier this month and spent several days sitting on the porch watching it rain– wishing I could bring it home with me. Alas, when I returned to the Rogue, I had no such luck.
At the watershed council, we work on rivers… on the ground. But that’s not the only kind of river out there. Five to ten years ago, the term “atmospheric river” was not commonplace. While their impact and frequency has only been increasing in recent years, so has scientists' and researchers’ ability to predict and understand these systems.
What is an atmospheric river?
These columns of condensed water vapor are essential functions of the global water cycle, carrying water vapor from the tropics to the poles – responsible for over 90% of moisture movement on Earth. Sometimes these rivers in the sky are called The Pineapple Express when the moisture originates from Hawaii and moves to the west coast.
Graphic courtesy of the National Oceanic and Atmospheric Administration
“The warmer sea surface temperatures associated with El Niño provide additional moisture to the atmosphere, contributing to the development of more intense atmospheric rivers and extreme precipitation.” ~Emily Mendez
Affecting clouds, air temperature, ice, and other factors, these moisture carriers shape our climate. They can bring large volumes of water a great distance– some can carry roughly an amount comparable to the flow at the mouth of the Mississippi River. When water vapor reaches land, it is precipitated into rain or snow across the landscape. Although this can come as a welcome reprieve during times of drought, there can also be serious flood damages associated with these events.
Graphic courtesy of American Geophysical Union
Why should I care?
Although atmospheric rivers are natural and beneficial to some extent, scientists are concerned with the increasing frequency and ferocity of these events. The warming of our climate contributes to more intense rivers and extreme precipitation events, making our communities more likely to experience heavy flooding events. These can trigger mudslides, road failures, and more disastrous consequences. Planning and communications for these events is incredibly important, and first responders and engineers must plan for and respond to these emergency situations.
This aerial photograph shows cars and homes engulfed by floodwaters in Pajaro, California on Saturday, March 11, 2023. (see original article)
Josh Edelson | AFP | Getty Images
Here at the watershed council, we keep our focus on the rivers meandering through the valley. However, it is important to maintain a big picture perspective on the impacts of atmospheric rivers (and other climatic variables) on our natural landscapes. As scientists and restoration specialists, we continue to grow and learn to better adapt and build resilience in our rivers and communities.
Interested in learning more about atmospheric rivers?
Check out some of our sources, including the National Oceanic and Atmospheric Administration, the Department of Energy, and Climate Centers across the country.
Comentários