RV Franklin Cruise Fr 7/93 (09FA0793)
======================================

Itinerary
=========

Depart Hobart       0900 Saturday 11th September, 1993
Arrive Nelson (NZ)  1600 Sunday 19th September, 1993
Depart Nelson (NZ)  2030 Tuesday 21st September, 1993
Arrive Townsville   0700 Tuesday 5th October, 1993


Scientific programs
===================

1. Ocean transport in the Tasman and Coral Seas


Principal Investigator
======================

Dr John Church, CSIRO Division of Oceanography


Other Investigators
===================

Dr Gary Meyers and Mr Fred Boland, CSIRO Division of Oceanography

Professor Matt Tomczak, Flinders University of South Australia


Cruise narrative
================

The ship sailed on time at 0900 on Saturday the 11th of September.  This 
cruise was the first with the new computer system.  While there had been 
some frantic preparation in the weeks leading up to the cruise some of the 
systems had not been fully tested.  This was partly because of the near-
impossibility of testing some of systems in port.  However, basic navigation 
and the CTD system were working at this stage.  The first CTD station was 
reached at 3pm on the Saturday.

CTD work continued smoothly for the first part of the 43S section.  Some 
problems were experienced with the ADCP software but this was going in an 
effective manner after about a day and a half.  By this stage the ADCP, CTD, 
Trimble GPS, Navtrak GPS, thermosalinograph and sounder acquisition
systems were all operational.  The main problem with the computer system 
for the next week or so was an annoying problem with the winch monitor 
software (which provided the CTD pressure readout for the winch driver) 
hanging.  This was exacerbated by the fact that the stand-alone PC version 
(which only provided wire out) could not be used safely because some of the 
magnets on the pulley had become ineffective leading to incorrect readings.

At about 1900 on Friday the 17th September a problem with the pitch control
gear for the main propeller was discovered.  One of the castings in the 
hydraulic control system had developed a crack and squirted hydraulic oil 
up to 5 feet when the propeller pitch was changed.  It would squirt oil a 
lesser distance at other times.  As it was not possible to repair at sea 
and there was no guarantee that it would not become worse (possibly 
rendering the main drive inoperative) the only option was to head for port.
Bluff was considered but was decided against because going into the head
sea to Bluff would have put extra strain on the cracked casting.  
Unfortunately this also made it virtually impossible to complete the 43S 
section.

We arrived in Nelson, New Zealand at 1600 (NZ time) on Sunday the 19th.
Howard Smiths (the ship's operators) had already started chasing a 
replacement part and the only spare to be found was at the LIPS factory in 
Holland.  Arrangements were made for the part to be flown out.  A repair was
also attempted on the existing part.  Eventually the repair was passed by the 
Lloyds surveyor, Max Cameron (Chief Engineer) and Bruce Maroc (Howard Smith).
The spare part was still shipped out from Holland and was insttalled during the
following port period.

We left the ship repair dock at 1530 on Tuesday the 21st as we would have 
been blocked in if we hadn't.  We moved to a vacant wharf while installation 
of the repair was completed and finally left Nelson at about 2030 on the 21st.

We did a test cast with the new small diameter bottles on the way north to 
Cape Reinga.  One bottle was lost completely and the analyses showed that 
most of the bottles had performed much better than on the previous cruise.
There were still a couple of obvious leakers though.

We began the 173E section in marginal conditions and behind time.  We thinned 
out the CTD stations as much as we reasonably could and would still have been 
able to reach Townsville on the 4th if we had had a few days of reasonable 
weather after leaving Nelson.  This was not to be - head seas and high winds 
led to very slow progress even though some stations were missed.  XBTs were 
dropped at these locations.

The stop in Nelson had, in effect, used up all our bad weather allowance so 
there was no option at this stage but to ask for an extra day to get enough 
of the scientific program completed for the cruise to be worthwhile.  This 
day was granted and the arrival data in Townsville changed to the 5th of 
October.  Eventually the weather improved and the slightly cut down CTD 
program was completed without further incident.  The last CTD station was 
completed at about 0400 on the 2nd of October.  This was followed by a gyro 
test to compare the ship's heading received through the Navtrak GPS navigator 
and through the new synchro-digital converter in the ADCP deck unit.  This 
showed heading-dependant difference with an amplitude of about 2 degrees.  
This will be pursued later.

The new computer system worked well and the new ops room layout is a big
improvement.


CTD Measurements During RV Franklin Cruise Fr7/93
==================================================

The CTD used throughout this RV Franklin cruise Fr7/93 was CSIRO CTD No. 2
(A Neil Brown Instrument Systems MkIII B profiler, Serial Number:  01-1013).
The Sensors on the profiler where :

     Sensor             Manufacturer          Resolution   Accuracy
     ======             ============          ==========   ========
     Temperature:       Rosemount PRT         0.0005C      0.003C
     Conductivity:      EG&G NBIS             0.001mmho    0.005mmho
     Pressure           Paine Instruments     0.1 dbar     6.5 dbar
     Dissolved Oxygen   Beckman Polarographic

The fast response thermistor had been removed prior to this cruise, in fact 
the thermistor had not been used on this instrument in the field.

CTD Temperatures are calibrated against water (0.010C) and phenoxybenzene 
(~27C) using platinum resistance thermometers as transfer standards.  The 
lab which carries out this calibration (The CSIRO Division of Oceanography 
Calibration Facility) is accredited by NATA, Australia's National Association 
of Testing Authorities, to calibrate CTDs to 0.003C at the water triple point 
and 0.004C at the phenoxybenzene point.  Both of these uncertainties are at 
the 99% level.  Calibration is carried out as often as practicable given the 
Franklin's itinerary.  

The CTD was calibrated in May 1993 and February 1994.  There was no 
significant difference between these two calibrations.  The constants from the
first of these calibrations were used.

All CTD temperatures are ITS-90.

The CTD pressure was calibrated against a deadweight tester in the "down cast" 
direction only.  In addition, the pressure at the first "in water" sample 
were used to derive an offset for each station.

Salinity calibration are based on in situ bottle data.  Laboratory checks are 
only maintained to ensure the sensor is operating correctly.  Using 1227
sample bottles out of a total of 1336, the difference between the CTD 
salinities and the water samples showed a standard deviation of 0.0020psu
for the whole water column.

The calibration technique follows that used by Bob Millard's group at WHOI 
closely.  The stations groups used were 1-18, 19-29, 30-40, 41-49, 50-60,
61-64 and 65-74.

Dissolved oxygen calibration is carried out using a method very similar to 
that described in Owens and Millard Jr (1985).  This method is to fit the 
downcast profile of dissolved oxygen to the sample bottles collected during 
the upcast.  

The difference between the CTD downcast oxygens and the sample bottle 
oxygens show a standard deviation of 3.10 umol/L (equivalent to 0.069 
mL/L) for the whole water column.  


CTD Data Collection and Processing
==================================

Three Sun Sparcstations are now used for all logging and analysis tasks on RV 
Franklin.  One is dedicated to data logging, another to user analysis and the
third is a spare.  The data that is logged (raw CTD data including flags 
at bottle firings) is very similar to that which was logged on the old system
and the user interface is similar.

All new data files are copied to the other machines on the network within an 
hour and daily backups are made to exabyte on two of the three machines.

Uncalibrated 2 decibar averages are provided for user analysis.

Post-cruise processing follows the following scheme: 

- there is an initial 'clean up' stage were station data is checked, unwanted 
  casts are removed, etc.

- a set of uncalibrated 2dB average files are produced, as well as summaries 
  of the data for each sample burst.  At this stage temperature and pressure 
  calibrations are put in.

- bad data (e.g. where something has got stuck in the conductivity cell) is 
  removed.

- the sample data is merged with the hydrology data, and some samples are 
  flagged as being 'unsuitable for calibration (e.g. due to large gradients).
  An iterative process then follows, where outliers are progressively removed 
  and a calibration constant (a conductivity ratio) is determined for each 
  station.

- once this has been done, calibrated 2dB average files are produced.  A 
  simple recursive filter is used to 'slow down' the faster sensors (pressure 
  and conductivity) to the slowest sensor (temperature - the response time 
  of the platinum resistance thermometer is ~.175 seconds).  Values are 
  checked for implausible gradients, and any ascending parts of the trace 
  are ignored (i.e. any values for which the pressure is less than the 
  maximum pressure for this cast so far are ignored).  At the same time 2dB 
  averages of oxygen current and oxygen temperature are calculated.

- the calibrated 2db averages are plotted, and the plots examined.  In 
  addition, T/S curves of groups are plotted and checked for agreement of the 
  deep T/S values.  The traces are also examined for density inversions, and 
  sections removed if this seems appropriate. 


Salinity and Dissolved Oxygen Measurements made during RV Franklin Cruise 
Fr7/93 (09FA0793).
=========================================================================

Salinity.  The water samples salinities where measured with a YeoKal Model 
601MkIII Inductive Salinometer that was standardised daily with IAPSO 
Standard Sea Water (SSW) Batch P122 (Cond Ratio: 0.99991).  
The accuracy of the salinnometer claimed by the manufacturer is 0.003 psu. 
(Yeo-Kal Electronics Pty Ltd, Brookvale, NSW, 2100, Australia)

Oxygen. The method used is a modified Winkler titration.  All oxygen values 
(Bottle and CTD were converted from umol/l to umol/kg using the salinity of 
the sample and the nominal temperature (25C) of the lab in which the 
analyses were done.


Nutrient Analyses
=================

Samples are collected in 15ml polypropylene tubes and frozen for up to 
one week before analysis using a Technicon AA2 system.  They are thawed at 
room temperature.

Nitrate determination is based on the reduction of nitrate in the sample 
to nitrite using a granulated cadmium reductor column and imidazole buffer.  
Nitrite then reacts with sulphanilimide to form a diazonium ion which reacts 
with napthylethylene dihydrochloride to form a coloured azo dye which is 
measured at 550nm.  Nitrite is also determined using the same chemistry 
without the use of a reductor column.

Dissolved phosphate is determined by reaction with acid molybdate in the 
presence of antimony ion.  Phosphomolybdate is then reduced by ascorbic acid 
at 37C and the blue complex measured at 880nm.

Reactive silicate is combined with acid molybdate and the complex reduced 
by methylaminophenol.  Interference by phosphate is eliminated by the addition
of oxalic acid which reacts with excess molybdate and the blue colour is 
measured at 820nm.

Nutrients are converted from umol/l to umol/kg using the nominal 
temperature of the chemistry lab on RV Franklin (25C) 



Table: Cruise Participants
==========================

        Fr7/93         Townsville - Brisbane       11 Sep - 5 Oct 1993


        Name                Responsibility        Affiliation
        -----------------------------------------------------

	Neil White          Chief Scientist        CSIRO DO
        Steve Rintoul       CTD watch              CSIRO DO
        Tony Woods          CTD watch              CSIRO DO
        Andrew Fiedler      CTD watch              Flinders University
        Rob Radcliffe       CTD watch              Flinders University
	Bernadette Heaney   CTD watch              CSIRO DO
        Bob Beattie         Computer support       CSIRO DO
        Val Latham          Nutrients/Salts/DOs    CSIRO DO
        Ruth Eriksen        Nutrients/Salts/DOs    Antarctic CRC
	Erik Madsen         Electronics            CSIRO DO


References
==========

Owens, W. Brechner and Robert C. Millard Jr. " A new Algorithm for CTD 
Oxygen Calibration." Journal Of Physical Oceanography, 15, 621-631. 1985




