Understanding the relationship between the weakening AMOC current and El Niño
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We had a terrific set of weather and climate questions, split between two panels at the MPR booth at the Minnesota State Fair this week. One really had me stumped, as a local listener asked about the relationship between El Niño and the weakening AMOC current that runs the length of the Atlantic Ocean. What’s the AMOC, anyways? Here’s what the National Ocean Service section of NOAA says:
“AMOC stands for Atlantic Meridional Overturning Circulation. The AMOC circulates water from north to south and back in a long cycle within the Atlantic Ocean. This circulation brings warmth to various parts of the globe and also carries nutrients necessary to sustain ocean life.”
AMOC moves the equivalent of 6,800 Olympic sized swimming pools of seawater every second! The Brits provide a helpful set of frequently asked questions about AMOC, as well, from their National Oceanography Centre.
Here’s one: is the Gulf Stream the same as AMOC? Well, kind of, as they write “It is common to confuse the Gulf Stream with the AMOC. While the Gulf Stream is an important part of the AMOC system, they are not identical.
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The Gulf Stream is a surface current partly driven by the wind. Think of the AMOC as a long journey and the Gulf Stream as a motorway for just one part of that trip. It carries warm water from the South Atlantic to the far north. When this “motorway” ends, the warm water takes different “A roads' to continue its journey northward.”
As meteorologists, it seems like most questions we’re getting are about El Niño and its impact on the coming winter. But, according to a 2021 study with scientists at the University of Arizona and Princeton/NOAA, AMOC could eventually play a large role in forcing really cold air over the Upper Midwest and other parts of North America.
Meanwhile, we’ve had some neat El Niño updates over the last few hours. Most recently, NOAA announced that they’re sending four autonomous Saildrone units into the heart of the El Niño circulation, steering from Hawaii to the equatorial Pacific.
These unmanned boats look like a combination of a sailboat and a submarine. The team of four units will scrub the waters for temperature changes every minute.
The United Nations just released a stern warning about El Niño intensity, calling the strengthening pattern something like we’ve “never before” seen. Mandy Thalhuber has a great write-up of what that means for Minnesota in this Updraft report.
Tying this together, and returning to our listener’s question that inspired this special Updraft edition, how could AMOC and El Niño tie together? In full transparency of the evolving science for these ocean currents thousands of miles away from Minnesota, we still really don’t understand how the shifting circulations will transform our seasons.
But if you made it this far, perhaps you know of some new research that’s connecting all the dots.
