Atmospheric Rivers (AR) are long corridors of concentrated moisture in the atmosphere. They usually appear at altitudes of about one mile above the earth's surface, flowing for thousands of miles, and on average are 400-600 km wide. ARs can create extreme rainfall and floods, disrupt travel, trigger mud slides, and cause catastrophic loss of life and property.
According to a Jan. 2013 Scientific American article, this atmospheric phenomenon was discovered about 15 years ago and given the name "atmospheric river" by researchers Yong Zhu and Reginald Newell who, "...noticed an odd feature in simulations of global wind and water vapor patterns that had been made by the European Center for Medium-Range Weather Forecasts."
According to the National Oceanic and Atmospheric Administration (NOOA) website, "Most flooding events that occur along the west coast of North America in winter are associated with the landfall of AR conditions." Although ARs can be detected by satellite instruments, a specialized atmospheric river observatory, or ARO, (see photo above/credit NOOA) has been developed which includes instrumentation uniquely adapted for capturing AR data. The Eureka Office of the National Weather Service, on Woodley Island, is slated to receive an ARO this coming January.
Just before Halloween KMUD News traveled to Woodley Island to learn more about Atmospheric Rivers and AR observatories.
Use the player below to hear this story, submitted by KMUD Community Journalist Bob Froehlich. This piece aired on KMUD Local News on Tues., Nov. 5, 2013 and includes interviews with National Weather Service Meterologist in Charge, Nancy Dean, and Mel Nordquist, Science and Operations Officer.
The entire 25 minute extended interview can be heard below.
Mobile AR Observatory. Credit: NOAA
- Scientific American article-"The Coming Megafloods"- Jan. 2013
- NOOA Atmospheric River Page
- Atmospheric River Smashes Records in Pacific Northwest-Climate Central.org
- Mysterious Atmospheric River Soaks California, Where Megaflood May Be Overdue-Scientific American Blogs
- ARkStorm: California’s other "Big One"
Photos/top to bottom: entrance to the NWS Woodley Island Facility, view of the facility's "Command Center", and meterologists Mel Nordquist and Nancy Dean.