Stations Tristan-A, -B and -C
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These files are from POL's 'Tristan Triangle Experiment' around Tristan
da Cunha which consisted of a series of BPR measurements made in a 'triangle'
(sites A,B,C) around the island between 1985-88, for details see

Spencer, R., Foden, P.R., McGarry, C., Harrison, A.J., Vassie, J.M.,
Baker, T.F., Smithson, M.J., Harangozo, S.A. and Woodworth, P.L. 1993.
The ACCLAIM programme in the South Atlantic and Southern Oceans.
International Hydrographic Review, 70, 7-21.

Bottom pressure at all three sites was found to be very coherent, for
example see

Hughes, C.W. and Smithson, M.J. 1996. Bottom pressure correlations in the
south Atlantic. Geophysical Research Letters, 23(17), 2243-2246.

For each instrument the Digiquartz transducer sensors
are the most quiet i.e.

tdca1.data-d  use  (c)
.. a2           .. (b)
.. a3           .. (a) or (b)
.. b2           .. (a) or (c)
.. c1           .. (a) or (c)
.. c2           .. (b) or (c

The -d in the filename indicates that long term drift has been removed from
each pressure channel.