HMAS COOK VKMS - 94105 Mk9 XBT System 

21/03/90 to 01/05/90

Many traces from this cruise have an error in the hit
bottom depth. The hit bottom depth is lower than the charted depth.
This is due to a timing error in recognition of the start of descent of the XBT probe.

This error has been documented by the CSIRO in "Quality Control
Cookbook for XBT Data, CSIRO Marine Laboratories Report No. 221, 1994"
in Section 2.8 as a 'Sippican Mk-9 Timing Delay Problem or Driver Error'.

The error is most obvious in shallow water areas less than 
80m and is intermittent. The error varies between approx.
5m to 25m.


For example no. 142 has a ships echo sounder depth of 16m, however the
XBT indicates a hit bottom depth of 5.8m.

Drop 172 HBR 6.5m, echo sounder 14m.


Traces from this cruise have an apparent electrical noise
fault e.g see drop 94105.005 22/03/90 0405Z. Traces have a
wavy oscillation which severly degrades the temperature data.

As there as is currently no QC flag for this type of fault they have been
rejected as 'LER' (leakage) either from the surface or at depth.

Traces 16 - 21 have inversions (NE Indian Ocean)

30 - 31 inversions.

In Great Barrier Reef there was salty, warm bottom water layer and
cooler fresh water upper layer.

In Tasman Sea there were a few traces with very sharp inversions.