|University of Alaska Fairbanks Summer 2012 Roundup:
“We threw everything at the ocean this year, including the kitchen sink!”
Contributed by Hank Statscewich & Peter Winsor, University of Alaska Fairbanks
Summer 2012: Researchers at the University of Alaska Fairbanks (UAF)
have kicked off an exciting field season with a massive sampling exercise
to measure ocean currents and stratification in the Chukchi Sea, a
marginal sea of the Arctic Ocean. The season started off with the
installation of CODAR Extended Long-Range SeaSondes in the villages of
Barrow, Wainwright and Point Lay. These specially-configured units feature a
second transmitter and transmit antenna to a traditional 5 MHz installation
to maximize the amount of energy transmitted from the antennas towards
ocean. Heavy ice cover lingered throughout the study area through most of
June and into mid-July, but by mid-August the ice started to break apart and
improvements in range from each of the three systems due to the hardware
augmentation started to become evident. Some preliminary analysis show
~25% improvement in range, from 180 km to 240 km!
In addition to the Long-Range SeaSondes, two higher resolution 25 MHz
systems are running in the village of Barrow to investigate the near shore
current fields around Point Barrow, the northernmost point in the United
States. The energetic currents of the region represent the oceanographic
link between the Pacific and Arctic Oceans via Barrow Canyon, a deep
submarine canyon that is located just 20 km from shore.
In August, principal investigator (PI) Tom Weingartner joined a multidisciplinary
science crew on board the US Coast Guard Cutter icebreaker
Healy. The group departed Dutch Harbor on August 4 en route to the
Chukchi. A dispatch from Tom relays the ice conditions, “Right now we
are at 71° 37’N, 160° 30’W and ice edge is no more than 5 miles away to the
south. Ice edge is very diffuse and easily navigable. Hanna Shoal was an
impressive mess with unbelievably large masses of grounded ice.” During
the cruise, Tom deployed 28 drifters in the study area and collected a
mountain of hydrographic and ocean current data.
||Background image: UAF SeaSonde antenna in Arctic during ice melt. Image courtesy of UAF.
|Current map with a strongly sheared current field
and huge front in the vertical sections (transition
between greens and blue colors between Barrow
and Wainwright). Black boxes are areas being
considered for offshore drilling.
|Follow That Front! Adaptive Sampling Using SeaSonde Data
The day that Tom stepped off the Healy and onto dry land, PI Peter Winsor and
crew stepped onto the Norseman II for a two week survey of the frontal structures
on the Chukchi Shelf. Winsor and crew towed an undulating CTD-optics
instrument through the water almost continuously for 12 days, collecting >4,000
casts through a 1,300 swath of ocean. The science party made extensive use of the
surface current maps produced by the SeaSondes to adaptively sample fronts,
convergence zones and coastal jets in the region. Winsor also deployed 20 drifters,
two gliders and a short-term current meter mooring. The drifters were initially
separated by 10 km but were placed on either side of a front, identified by the
CODAR and towed instrument, with a temperature difference of >6 °C. Two Webb
Slocum gliders were deployed alongside the drifter clusters to gain a Lagrangian
perspective of the frontal physics. For these glider deployments, the UAF team
relied on the glider piloting expertise of the Rutgers University Coastal Ocean
Observation Lab. While the UAF researchers were at sea in the Chukchi, the glider
pilots were comfortably situated in New Jersey.
|Chukchi Sea SeaSonde-derived hour-averaged
surface current map 22 August
2012 16:00 hrs UTC.
A total of ~100 drifters were deployed in the Chukchi Sea this summer. Apart from
giving the science team insights into the circulation patterns of the area, the
drifters will also be used for detailed comparisons with the CODAR-derived surface
currents. Project data, including real-time surface current vectors can be viewed on
the project website: http://dm.sfos.uaf.edu/chukchi-beaufort/index.php
Funding for this research is provided by the United States Department of the Interior, Bureau of Ocean
images provided courtesy of University of Alaska Fairbanks.