Geoscience Reference
In-Depth Information
Figure 5.15
A temperature/conductivity/
depth probe (CTD) with a series of water
samplers is deployed to provide vertical
pro
les for physical and chemical
parameters. (Credit: Peter Bucktrout, BAS)
ocean. Applying such delicate sensors under freezing conditions requires
special care and experience.
There are not many research vessels, so ship-borne measurements are not
frequent enough or extensive enough to characterise comprehensively the highly
variable environment. Therefore autonomous observation platforms are used as
well. They can be moored, drifting or self-propelled. Moorings provide data
collection for a particular locality and consist of a ground weight and buoyancy
floats, which keep a wire upright in the water column. On the wire, instruments are
fixed which are able to measure time series of temperature, salinity, currents and
other variables. The data are stored in a memory and can be retrieved after the
mooring is recovered. Special sensors, upward-looking sonars, measure the sea
ice thickness by an echosounder, which determines the distance from the
instrument to the ice underside. Sinking particles can be collected with
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