***  Documentation for the CTD data collected on RRS Charles Darwin  cruise                                                         
24  (Jun - Jul 1987) by the School of Ocean Sciences,  University of Wales,                                                         
Bangor, under the direction of E.D. Barton. ***                                                                                     
                                                                                                                                    
                              *** WARNING ***                                                                                       
    Transmissometer data are unreliable for this cruise, use with caution.                                                          
                                                                                                                                    
The  instrument  used was a Neil Brown CTD/fluorometer and  Niskin  rosette                                                         
sampler.  The  CTD functioned well through most of the cruise.  The  sensor                                                         
performance  was  checked  against 266  salinity  determinations  on  water                                                         
samples  from  various depths,  but concentrated on the bottom  waters  and                                                         
uniform  surface  layer,  and 140 reversing  thermometer  observations.  No                                                         
significant  offset  was evident in temperature.  CTD salinity  during  the                                                         
first  50  stations  agreed  within   0.006  mean  difference  with  bottle                                                         
salinities  determined  on a Guildline Autosal,  but an increasingly  large                                                         
difference became apparent during later stations. At the last five stations                                                         
of  the cruise differences were about 0.025,  but sufficient  water  bottle                                                         
samples  were taken to allow adjustment of the CTD values.  Slight  leakage                                                         
around  the conductivity head is suspected as the cause of the  drift.  The                                                         
transmissometer,  fluorometer and CTD oxygen probe appeared to have  worked                                                         
well initially. However the transmissometer began behaving erratically, and                                                         
the  fault  could  not be located.  Oxygen  data  appeared  reasonable  but                                                         
unfortunately no facility for calibration of the sensor was available.                                                              
