AIDJEX Bulletin #40 - Polar Science Center - University of Washington

An example of a large-scale buoy array planned for deployment by aircraft
during the FGGE is shown in Figure 4. This array of 20-30 buoys would
be deployed in the fall of 1978 using four C-130 flights. The availability
of airstrips in Canada and Greenland closer to the Arctic Basin than Thule
makes the majority of the deployments feasible from smaller aircraft such as
the DHC-6 Twin Otter.
When a major purpose of a buoy deployment is to collect surface barometric
pressure data for a full year, there is good reason for concern about
calibration drift of the sensor. It is always economic to invest in a sensor
in which confidence can be placed for the duration without resorting to field
checks. These is some evidence that we are approaching a time when several
different sensors will merit this confidence. For the FGGE, where many different
types of sensors are to be deployed by many different groups, it may
be desirable to check the calibrations prior to the second special observing
period. Again, aircraft offer a means of carrying out this task efficiently,
since the same large distances covered during deployments are involved in
overflying buoys for calibration.
Since, to achieve maximum range, turbine engines used in long-range
aircraft must be operated at altitudes of 20,000-40,000 feet, it is impractical
to consider low-level flights to measure surface pressure directly.
This problem is compounded by the real difficulty of measuring static pressure
from a fast-moving aircraft. Instead, the calibration can be made by
dropping pressure sensors to the surface with radio telemetry to the aircraft.
This technique is common for temperature sounding, which will be carried out
during the FGGE over large areas of the tropical oceans from C-141 aircraft.
The pressure sensor added to such dropsondes need not be expensive, since it
would be expected to operate for less than an hour and through only one pressure
excursion. Provision for survival of the dropsondes after water or sea
ice landing would be necessary to allow the temperature of the sensor to
stabilize so that several minutes of good data could be collected.
Parachute deployment of data buoys, together with the proven performance
of satellite data collection and tracking, aremaking dramatic changes in the
nature of studies of Arctic air-ice-ocean interaction. It seems likely that
aircraft deployments will play an increasingly important role wherever surface
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