On the Nature and Origin of Water Masses in Herald Canyon, Chukchi Sea
On the Nature and Origin of Water Masses in Herald Canyon, Chukchi Sea
Abstract:
A significant fraction of the Pacific water entering Bering Strait
flows onto the western Chukchi Sea shelf, yet historically there have
been limited observations documenting the circulation, transformation,
and fate of the water. Here we use hydrographic and velocity data from
three shipboard surveys of Herald Canyon in the
northwest Chukchi Sea in 2004, 2008, and 2009, together with mooring
timeseries in Bering Strait, to investigate the water masses in the
canyon and their possible source regions. We find that a large amount
of Bering summer water in the western channel of the strait follows a
relatively direct route into Herald Canyon during the summer months,
with an estimated advective speed of 10-20 cm/s. However, while the
winter water observed in 2004 was consistent with a Bering Strait
source (with a slower advective speed of 5-8 cm/s), the dense water in
the canyon during 2008 and 2009 was more in line with a northern
source. This is consistent with shipboard data collected to the west
of the canyon and with previously reported measurements of winter
water on the East Siberian shelf. Large-scale wind patterns and
polynya activity on the shelf are also investigated to assess their
influence on the presence of dense water in Herald Canyon.
flows onto the western Chukchi Sea shelf, yet historically there have
been limited observations documenting the circulation, transformation,
and fate of the water. Here we use hydrographic and velocity data from
three shipboard surveys of Herald Canyon in the
northwest Chukchi Sea in 2004, 2008, and 2009, together with mooring
timeseries in Bering Strait, to investigate the water masses in the
canyon and their possible source regions. We find that a large amount
of Bering summer water in the western channel of the strait follows a
relatively direct route into Herald Canyon during the summer months,
with an estimated advective speed of 10-20 cm/s. However, while the
winter water observed in 2004 was consistent with a Bering Strait
source (with a slower advective speed of 5-8 cm/s), the dense water in
the canyon during 2008 and 2009 was more in line with a northern
source. This is consistent with shipboard data collected to the west
of the canyon and with previously reported measurements of winter
water on the East Siberian shelf. Large-scale wind patterns and
polynya activity on the shelf are also investigated to assess their
influence on the presence of dense water in Herald Canyon.