***  Documentation for the CTD data collected on RRS John Biscoe Cruise 03                                                          
(15 Nov 1981 - 03 Mar 1982)  by the British Antarctic  Survey,  Cambridge,                                                          
U.K., under the direction of R.B. Heywood.  ***                                                                                     
                                                                                                                                    
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      *  WARNING: Salinity data are highly suspect, see note below  *                                                               
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DATA COLLECTION                                                                                                                     
The  instrument  used was a Plessey 90/40 CTD.   Observed parameters  were                                                          
pressure,  temperature  and  conductivity.  All  sensors  were  calibrated                                                          
before  and after the cruise.   Up to 12 water bottles were mounted  on  a                                                          
Rosette  sampler  and  4 pairs of reversing  thermometers  were  attached.                                                          
Water  bottles were triggered on the downcast at 10m and at the bottom  of                                                          
the  cast,  the remainder being fired on the upcast (mainly  for  chemical                                                          
samples).  Data were collected on the downcast.                                                                                     
                                                                                                                                    
CALIBRATION                                                                                                                         
Reversing  thermometers  were calibrated at the Deacon Laboratory  of  the                                                          
Institute  of Oceanographic Sciences.   The pressure sensor  was  compared                                                          
with  a Bourdon gauge which had been calibrated at the  National  Physical                                                          
Laboratory.  The  accuracy  of  the temperature  data  is  thought  to  be                                                          
+/-0.01degC.                                                                                                                        
                                                                                                                                    
DATA PROCESSING                                                                                                                     
Calibrations  were applied and the data despiked by rejecting data  values                                                          
outside  of predetermined tolerances.  Data values were then  averaged  to                                                          
provide data at 1 decibar intervals.                                                                                                
                                                                                                                                    
** WARNING **                                                                                                                       
The  data  are derived from instruments which were  laboratory  calibrated                                                          
(for  pressure  and temperature anyway), but not  finally  adjusted  using                                                          
reversing thermometers or salinity derived from in situ samples.  The data                                                          
required  for  this final adjustment are either missing or of too  poor  a                                                          
quality for calibration. Therefore these CTD data are of varying quality -                                                          
the  temperature  data are reasonable,  but the salinity data  are  HIGHLY                                                          
SUSPECT and should not be used for detailed physical studies. The salinity                                                          
data  are  probably  just  about good enough for  setting  the  scene  for                                                          
biological  studies  since they can be used to show  relative  changes  in                                                          
space  or  time  but are not accurate enough  to  show  absolute  salinity                                                          
levels.                                                                                                                             
                                                                                                                                    
Note  that  it was not possible to recover and reprocess all of  the  data                                                          
collected  on  this cruise to produce 1 decibar values.  For  those  casts                                                          
which were not reprocessed an earlier version of the data is held by BODC.                                                          
Few processing details are available for these casts.  The data are not at                                                          
regular  pressure  intervals.  Salinities from  the  bottle  samples  were                                                          
determined  the  British Antarctic Survey using a  Guildline  Salinometer.                                                          
Some time after these data were supplied to BODC the salinometer was found                                                          
to  be  faulty which casts doubt on the accuracy of the  salinity  values.                                                          
The CTD casts to which these comments apply are as follows:                                                                         
                                                                                                                                    
BODC Series Reference No.      Originator's Reference                                                                               
                                                                                                                                    
      73357                    JB 3/51                                                                                              
      73658                    JB 3/222                                                                                             
      73683                    JB 3/231                                                                                             
      74348                    JB 3/552                                                                                             
      74742                    JB 3/713                                                                                             
      74778                    JB 3/726                                                                                             
      74791                    JB 3/727                                                                                             
      74809                    JB 3/733                                                                                             
      74822                    JB 3/744                                                                                             
      74846                    JB 3/754                                                                                             
      74871                    JB 3/760                                                                                             
      74895                    JB 3/769                                                                                             
      74914                    JB 3/777                                                                                             
      74938                    JB 3/785                                                                                             
      74975                    JB 3/799                                                                                             
      74999                    JB 3/808                                                                                             
      75014                    JB 3/841                                                                                             
      75051                    JB 3/859                                                                                             
      75075                    JB 3/873                                                                                             
      75099                    JB 3/890                                                                                             
      75118                    JB 3/917                                                                                             
      75143                    JB 3/935                                                                                             
      75167                    JB 3/951                                                                                             
      75180                    JB 3/979                                                                                             
      75211                    JB 3/998                                                                                             
      75235                    JB 3/1014                                                                                            
      75247                    JB 3/1022                                                                                            
      75259                    JB 3/1030                                                                                            
      75272                    JB 3/1049                                                                                            
      75296                    JB 3/1060                                                                                            
      75315                    JB 3/1074                                                                                            
      75339                    JB 3/1085                                                                                            
      75352                    JB 3/1102                                                                                            
      75376                    JB 3/1111                                                                                            
      75407                    JB 3/1123                                                                                            
      75420                    JB 3/1133                                                                                            
      75432                    JB 3/1139                                                                                            
      75456                    JB 3/1162                                                                                            
      75468                    JB 3/1171                                                                                            
      75493                    JB 3/1176                                                                                            
      75512                    JB 3/1185                                                                                            
      75536                    JB 3/1196                                                                                            
      75561                    JB 3/1210                                                                                            
      75585                    JB 3/1221                                                                                            
      75604                    JB 3/1236                                                                                            
      75641                    JB 3/1254                                                                                            
      75665                    JB 3/1267                                                                                            
      75689                    JB 3/1282                                                                                            
      75721                    JB 3/1303                                                                                            
                                                                                                                                    
The salinity data from the CTD have been compared with other  measurements                                                          
made in this region and also with the Levitus Atlas.  The data which  have                                                          
not  been  reprocessed  are within about 0.02 ppt  of  data  collected  on                                                          
various cruises including Discovery II (1929-31) and within about 0.03 ppt                                                          
of the Levitus Atlas salinities. The reprocessed salinity data are between                                                          
approximately  0.1  -  0.2  ppt lower than the data  which  has  not  been                                                          
reprocessed.                                                                                                                        
                                                                                                                                    
References:                                                                                                                         
Fofonoff,  N.P.  and Millard Jr., R.C. 1983 Algorithms for the computation                                                          
of  fundamental  properties  of  sea water.  UNESCO Technical   Paper   on                                                          
Marine Science 44                                                                                                                   
                                                                                                                                    
Levitus,  S.  1982  Climatological Atlas of the  World  Ocean.  NOAA  Pro-                                                          
fessional Paper No. 13. US Government Printing Office. 173pp                                                                        
