Seasonal and Decadal Geostrophic Pathways of Pacific and Atlantic Waters in the Arctic Amerasian Basin From Observations

Abstract

We examine the geostrophic pathways of Pacific and Atlantic Waters along isopycnal surfaces of the Arctic Ocean from Montgomery potentials using two observation-based climatologies: the World Ocean Atlas and the Monthly Isopycnal & Mixed-layer Ocean Climatology. The decadal mean circulation (2005–2017) shows an anticyclonic circulation for both the summer Pacific Waters (sPW) and winter Pacific Waters (wPW, although somewhat weaker) in the Canada Basin with subduction along the Chukchi plateau for both water masses. On the wPW layer, the diagnostics also highlight a year-long persistent flow from Herald Canyon on Chukchi Shelf to the Canadian Arctic Archipelago around the Canada Basin. Outflows are found at Nares and Fram Sraits at the density of sPW and wPW. These outflowing waters, previously reported as Pacific Waters, are found here to originate from the Eurasian shelf. Deeper, the Atlantic Waters flow anticyclonically around Northwind Ridge and cyclonically along the Alaskan shelfbreak forming a boundary current. The subduction of warm water along the Alaskan and Chukchi shelves is found to occur in summer on the sPW isopycnal layer, thus contributing to transferring heat into the center of the gyre. However, an advection of virtual Lagrangian particles from Pt. Barrow suggests that processes operating on timescales shorter than a month or at interannual timescales are the main contributors to the heat build up observed over the past two decades. This analysis supports the hypothesis that high frequency processes are key in shaping the subsurface heat reservoir of the Canada Basin.