March 2003 deployment of the Autonomous Ocean Flux Buoy at the North Pole EnviromentalObservation Station
The second NPS Autonomous Ocean Flux BUoy was deployed during late April
2003 as part of the
Environmental Observatory. The following photographs
and brief descriptions summarize the sequence of events leading to the
deployment of the flux buoy at the very remote Arctic site near the North Pole.
All gear and personnel were flown North from a staging area at Resolute
Bay, NT, Canada, through Alert to Ice Camp Borneo on a chartered Hawker
Siddley 748 run by First Air. The 2003 deployment was made more complicated
by the 6 km distance between Ice Camp Borneo and the runway. Equipment had
to be ferried to the ice camp and remote deployment sites via Russion MI8
Moving around the ice flow
The buoy and deployment gear were moved from the runway to the deployment site
with a Russion tractor and sled. The tractor was brought to Borneo to
aid in runway creation and maintainene. The buoy site was chosen
after a survey to find the oldest and thickest multi-year ice which had the
best chance of surviving ice cracking and ridging (and destruction of the buoys). The ice
flow will crack, form leads and ridge as it moves out of the central Arctic toward the Atlantic Ocean over
the next year. The cluster of meterological, ice flux and ocean buoys was assembled
over a four day period.
Mid-deployment of Flux buoy
The buoy was deployed aproximately 500 meters from the runway
in 2.7 meter thick ice.
Snow was scraped off the ice with the aid of the Russian tractor and a
large power auger was used to drill an 11" hole through ice. The tripod was
used to lower an instrumented frame through the ice, the top of which
can just be seen in the ice hole. The next step is to attach the
instrument frame to the bottom of the buoy housing.
With the buoy seated into the hole, the radome was attached and
instrument cables coming up from the suspended instruments were connected
to the internal electronics. The entire buoy
deployment took aproximately 16 hours.
Testing the Buoy
With the buoy physically deployed, each component of the buoy system was
checked with a laptop computer in the wind break tent. Weather was
excellent, but the tent still provided important shelter to the buoy group
out on the ice away from the main camp. In the background, a group
of tourist skiiers can be seen.
The full data stream from the flux buoy is periodically sent back to
the Naval Postgraduate School by an Iridium satelite modem, which also
provides two way communication to diagnose problems and change setups
in the instrument system. If the Iridium link fails, a shorter data
message is sent back by the older Argos satellite system. A Global
Positioning System located with these antennas provides accurate time
and position measurements every 15 minutes. The antennas for these
systems are enclosed by the orange and white radome at the top of the buoy.
The deployed flux buoy
The buoy assembly was completed with a radome cover over the antennas to reduce snow
buildup and provide some protection from potentially destructive Arctic foxes which
have an unusual interest in our instrument systems. Measurments of ocean fluxes are
made from an instrument cluster 4.5m below the ice within the 30-50m deep ocean mixed
layer which sits above the strongly stratified halocline. A very low power acoustic travel time
current sensor, a stable conductivity cell and a very high resolution thermistor measure
velocities, salinity and temperature in the same small volume. Correlating fluctuations of
vertical velocity with horizontal velocity fluctuations, temperature fluctuations and
salinity fluctuations provide estimates of the vertical transport of momentum, heat and salt
through the ocean mixed layer (see for example, McPhee and Stanton, Turbulence in the statically unstable oceanic
boundary layer under Arctic leads, Journal of geophysical Research, pp6409-6428,