Abstract:
Hydrographic and tracer data from 2002 illustrate Atlantic water pathways and
variability in the Mendeleev Ridge and Chukchi Borderland (CBLMR) region of the
Arctic Ocean. Thermohaline double diffusive intrusions (zigzags) dominate both the Fram
Strait (FSBW) and Barents Sea Branch Waters (BSBW) in the region. We show that
details of the zigzags’ temperature-salinity structure partially describe the water masses
forming the intrusions. Furthermore, as confirmed by chemical tracers, the zigzags’
peaks contain the least altered water, allowing assessment of the temporal history of the
Atlantic waters. Whilst the FSBW shows the 1990s warming and then a slight cooling, the
BSBW has continuously cooled and freshened over a similar time period. The newest
boundary current waters are found west of the Mendeleev Ridge in 2002. Additionally, we
show the zigzag structures can fingerprint various water masses, including the boundary
current. Using this, tracer data and the advection of the 1990s warming, we conclude
the strongly topographically steered boundary current, order 50 km wide and found
between the 1500 m and 2500 m isobaths, crosses the Mendeleev Ridge north of 80°N,
loops south around the Chukchi Abyssal Plain and north around the Chukchi Rise, with
the 1990s warming having reached the northern (but not the southern) Northwind
Ridge by 2002. Pacific waters influence the Atlantic layers near the shelf and over the
Chukchi Rise. The Northwind Abyssal Plain is comparatively stagnant, being ventilated
only slowly from the north. There is no evidence of significant boundary current flow
through the Chukchi Gap.
