Episodic Extrema of Surface Stress Energy Input to the Western Arctic Ocean Contributed to Step Changes of Freshwater Content in the Beaufort Gyre

Abstract

The recent dramatic decline of sea ice in the western Arctic Ocean changes the transfer of momentum across the ice‐ocean boundary layer. The surface stress energy input through the surface geostrophic current in the Beaufort Gyre (BG) based on a numerical model is 0.03 mW/m in 1992–2004 versus 0.23 mW/m in 2005–2017. This energy input is primarily concentrated over the southern Canada Basin and the Chukchi Sea. It is 1.38 × 10 J in observations versus 4.90 × 10 J in the model in the BG during 2003–2014. We find that some well‐known freshwater changes in the BG over 1992–2017 resulted from episodic extrema of energy input in 2007, 2012, and 2016. In particular, most of the energy input in 2007 was transformed into potential energy (57%) which resulted in a new state of freshwater budget. Our study suggests that as of 2016, the BG had not yet reached a saturated freshwater state. Our results provide a way to predict the future changes of BG freshwater content.