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Compared
with spring 2007, weather and particularly ice
conditions were much more favorable for the Twin
Otter CTD survey during 2008. Landings by skiplanes
on unprepared ice floes were greatly aided by the
nearly universal presence of smooth, first year
ice which made locating landing sites relatively
easy.
Thanks
to NSF's
International Polar Year (IPY), 2007-2008 Initiative,
the NPEO hydrographic survey in 2008 began
March 20 with the
IPY extended
sampling program of the Beaufort Sea by
Twin Otter.
Fifteen CTD-Chemistry surface stations were obtained
across the southern Beaufort from 136 °West
out to 163° West, in unusually cold air temperatures.
Trying
to extend the IPY Beaufort coverage farther north
than was reachable from Deadhorse, Alaska in the
skiplane, a second Twin Otter on standard (thin)
wheels and with dual, long-range ferry tanks flew
two days in mid-April north from Deadhorse, seeking
to drop Airborne
eXpendable Conductivity, Temperature, and Depth
probes ( AXCTD.pdf ) into open leads, and record
the profiles without landing. The relatively smooth,
uniform ice cover with persistently cold air temperatures
presented few cracks new enough to be feasible
drop targets, especially in the northwest Beaufort,
but eight successful CTD profiles were obtained.
Two had to be repeated to penetrate a thin slush
layer.
The
23 IPY Beaufort Sea CTD profiles are being compared
with stations obtained in the same area by the
WHOI's
Beaufort Gyre Expedition Project using the
Canadian Coast Guard Icebreaker Louis S. St-Laurent on its Joint
Western Arctic Climate Study (JWACS) cruise during August 2007. This comparison spans
the extraordinary melting of September 2007 and
subsequent freezeup through the following winter.
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