First Observational Evidence of Stable Beaufort Circulation, Which Could Be Precursor to Massive Freshwater Release – ScienceDaily


A new study provides the first observational evidence for the stability of anticyclone Beaufort Gerry, the dominant circulation of the Canada Basin and the largest freshwater reservoir in the Arctic Ocean.

The study uses a newly expanded record of “dynamic ocean topography” satellite data from 2011-2019 provided by two of the co-authors, along with an extensive hydrographic data set from 2003-2019, to quantify the changing eddy sea surface height in recent years.

Previous observations and modeling that relied on previous dynamic ocean topography data up to 2014 documented that the circulation was enhanced and the freshwater content increased by 40% compared to climate science in the 1970s. Circulation stabilization could be a harbinger of a massive release of freshwater, which could have major ramifications including affecting the Atlantic Meridian Overturning Circulation (AMOC), a key component of global climate.

Beaufort Gear’ shifted to a semi-steady state as the increase in sea surface height of the eddy slowed and the freshwater content decreased. In addition, the cold Halocline layer, which insulates warm/salty Atlantic waters at depth, has been greatly weakened by fewer cold and brackish water inputs upstream. of the Pacific Ocean and the Chukchi Sea shelf, as well as greater incorporation of lighter waters from the eastern Beaufort Sea.This recent transition of Beaufort Geary is associated with a southeastward shift in its position as a result of the difference in regional wind forcing,” according to a journal article titled “The Last Beaufort State Transition in the Arctic Ocean.” Northern “, which was published in Natural Earth Sciences.

“Our results suggest that continued thinning of the cold Halocline layer can modify the current steady state, allowing for the release of fresh water,” the article states. “This, in turn, could revitalize the subarctic North Atlantic region, affecting the AMOC.”

Because there can be many potential local and remote impacts of the changing circulation on the hydrographic structure, physical processes, and ecosystem of the Arctic, “it is critical that we better understand the factors associated with these changes—including the underlying causes,” the article notes.

“People should be aware that changes in Arctic Ocean circulation could threaten the climate. It’s not just the melting of ice and animal habitat loss that should be a concern,” said Begin Lin, lead author of the paper. Lin, an associate professor in the School of Oceanography at Shanghai Jiao Tong University in China, conducted his research as a postdoctoral investigator at the Woods Hole Oceanographic Institution (WHOI) in Massachusetts.

Since the circulation is the largest reservoir of fresh water in the Arctic Ocean, “if this fresh water were released and ended up circulating in the North Atlantic, it could affect the circulation circulation and, in extreme cases, even disrupt it,” said the co-author Robert Pickart. , a senior scientist in the World Health Organization’s Department of Physical Oceanography.

The study, which includes an examination of the long-term trends of the Beaufort Geary and the causes of thinning of the Halocline cold layer, quantifies the evolution of the circulation in terms of sea-level rise as well as its freshwater content. “Both indicate that Beaufort Gear has settled into the second decade of this century,” Lane said.

The study also addresses the causes of halocline thinning significantly with the development of circulation. The study suggests that a recent decrease in the amount of winter waters of Pacific origin emerging from the Chukchi Sea accounts for some of the mitigation, and that the enhanced influence of the eastern Beaufort Sea – due to the southeast shift of circulation – is also likely to contribute to the mitigation. .

The last documented case of the circulation” does not represent a return to the initial state of 2003 when the circulation was weak and partially present in the southeastern basin. Instead, under the strengthening wind stress convolution, the circulation has continually intensified even though it is contracting, and maintained its excess water reserves. Fresh,” the article notes.

The goal with circulation, Lin said, is to understand the mechanisms behind its changes, which may eventually allow scientists to predict what the circuit might do in the future.

“The community has been overwhelmed by the fact that this department has kept growing and growing, and everyone is expecting it to fire,” Picart said. “Wouldn’t it be something if the circulation system and the accumulation and release of fresh water became somewhat possible? Then, perhaps, we could also shed light on what climate warming is going to do to that system.”

The study was funded by the National Science Foundation; the National Oceanic and Atmospheric Administration; the Shanghai Pujiang Program and the Shanghai Frontiers Science Center for Polar Sciences; a project of the European Space Agency and the Natural Environment Research Council; Arctic Challenge of Sustainability Projects of the Ministry of Education, Culture, Sports, Science and Technology, Japan; and the Arctic Challenge for Sustainability II (ArCS II). Co-authors Harry Horton and Michael Tsamados of University College London provided updated dynamic ocean topography data from 2011-2019 for the study. Co-authors Motoyo Itoh and Takashi Kikuchi of the Japan Agency for Marine Geosciences and Technology (JAMSTEC) provided docking data for Beaufort Gyre source waters.


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