The study, which includes an examination of long-term trends of the Beaufort Gyre and the causes of the thinning of the cold halocline layer, quantifies the evolution of the gyre in terms of its sea surface height as well as its freshwater content. “Both of these indicate that the Beaufort Gyre has stabilized in the second decade of this century,” Lin said.
The study also addresses the causes of the halocline thinning considerably as the gyre has evolved. The study notes that the recent decrease in the amount of Pacific origin winter water exiting the Chukchi Sea explains some of the thinning, and that the enhanced influence from the eastern Beaufort Sea – due to the gyre’s southeastward shift– likely also contributes to the thinning.
The recent documented state of the gyre “does not represent a return to the initial condition of 2003 when the gyre was weak and located partially in the southeastern basin. Instead, under the strengthened wind stress curl, the gyre has continuously intensified even though it has contracted, and it has maintained its excess freshwater storage,” the article notes.
Lin said a goal regarding the gyre is to understand the mechanisms behind its changes, which ultimately could allow scientists to predict what the gyre might do in the future.
“The community has been confounded by the fact that this gyre has kept growing and growing, and everyone is expecting it to release,” Pickart said. “Wouldn’t it be something if the gyre system and its freshwater accumulation and release could be become somewhat predictable? Then, perhaps, we could also shed light on what a warming climate is going to do to this system.”
Funding for the study was provided by the National Science Foundation; the National Oceanic and Atmospheric Administration; the Shanghai Pujiang Program and Shanghai Frontiers Science Center of Polar Science; the European Space Agency Project and Natural Environment Research Council; the Arctic Challenge for 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 Heorton and Michel Tsamados of University College London provided the updated dynamic ocean topography data from 2011-2019 for the study. Co-authors Motoyo Itoh and Takashi Kikuchi of the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) provided the mooring data regarding the Beaufort Gyre source water.
Authors: Peigen Lin1,2, Robert S. Pickart2, Harry Heorton3, Michel Tsamados3, Motoyo Itoh4, and Takashi Kikuchi4
1School of Oceanography, Shanghai Jiao Tong University, China
2Woods Hole Oceanographic Institution, Woods Hole, MA, USA
3Department of Earth Sciences, Centre for Polar Observation and Modelling, University College London, UK
4Institute of Arctic Climate and Environment Research, Japan Agency for Marine-Earth Science and Technology, Yokosuka, Japan
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