RV Franklin Cruise Fr 7/92 (09FA0792)
======================================

Itinerary
=========

Depart Townsville  0800 Saturday 19th September, 1992
Arrive Brisbane    0630 Tuesday 6th October, 1992


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

1. Ocean transport in the Tasman and Coral Seas

2. Dimethyl sulphide in surface and sub-surface waters


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

Dr Graham Jones, James Cook University


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

Weather was good when we departed Townsville - no clouds, wind of less than 
10 knots.  Boat drill at 0900 was followed by Master's and Chief Scientist's
briefings.

The first single Niskin cast for Graham Jones was completed at about 1000 and 
these were continued at roughly four hour intervals.  Several trichodesmium 
blooms were sampled.  DMS and DMSP were detected.

Late Tuesday (September 22) we arrived at the mooring location and the 2,000 
metre mooring was recovered.  The 4,000 metre mooring was recoverd early 
Wednesday.  However, both of the moored ADCPs were not functioning properly 
and we could not redeploy the moorings.  The most offshore (4,400 metre) 
mooring was recovered on Thursday.  By this time the deck was so cluttered that
no more moorings could be recovered until some were redeployed.  Friday
(September 25) was lost to bad weather and on Saturday the most offshore 
mooring was redeployed in marginal conditions.  The weather deteriorated 
during the deployment and the 4,000 metre mooring could not be deployed 
until 1430 on Sunday.  On Monday 28 the weather was excellent.  The 2,000 
metre mooring was deployed by 0800 and the 700, 200 and 100 metre moorings 
were recovered by about 1300.  On Tuesday, the final three moorings were 
deployed.  During the nights when mooring work could not be undertaken,
either the ADCPs for the moorings were tested or ship-mounted ADCP data was 
collected.

The short CTD section was finally commenced late on Tuesday, October 29.  
Only two stations were completed before the winds reached 45 knots.  By 
Wednesday the weather was good enough to continue CTD stations.  Over the 
next few days, CTD stations were continued in sloppy weather and the final 
CTD station was completed about 2330 on Sunday.  Franklin then steamed north
and we arrived in Brisbane at 0630 Tuesday, October 6.

The CTD section is so short that it may not be useful for WOCE purposes.

The CTD station numbering starts at 15 - the first 14 numbers were used for 
bottle stations for the DMS work.


CTD Measurements During RV Franklin Cruise Fr7/92
==================================================

The CTD used throughout this RV Franklin cruise Fr7/92 was CSIRO CTD No. 1
(A Neil Brown Instrument Systems MkIII B profiler, Serial Number:  01-1073).
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 August 1992 and the constants from that calibration 
were used for this cruise.  

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 439
sample bottles out of a total of 491, the difference between the CTD 
salinities and the water samples showed a standard deviation of 0.0023psu
for the whole water column.

The calibration technique follows that used by Bob Millard's group at WHOI 
closely.  The stations (15 - 45) were treated as a single group.

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 2.51 umol/L (equivalent to 0.056 
mL/L) for the whole water column.  

Apart from the first three stations (15, 16 & 17) the dissolved oxygen sensor 
appeared to provide data of reasonable quality and consistency.  There was 
no DO calibration for stations 15 - 17 as the sampling for these stations 
(15 - bottle test, 16 - no samples and 17 - too few satisfactory samples) 
was not suitable.  Stations 23 and 24 had no samples, but the sensor 
performance seemed consistent for stations 19 through 25, allowing a
satisfactory interpolation across this gap.  A total of 417 of the 459
available bottles were used in the fitting.


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

A PDP 11/73 computer with a 150Mb hard disk was used as the primary data 
logging device.  Data is logged directly to hard disk, whilst simultaneously 
recorded on audio tape.  Logging is commenced before the CTD profiler is 
deployed and downcast is normally logged as a single file.  Positions and 
times are logged automatically.  Complete upcasts are recorded and the 
locations of samples are flagged in the data file.  15 second bursts are used
for the calibration.

Following completion of the station uncalibrated averaged files are sent 
over the network to a VAX 11/750 for use on-board during the cruise and 
the raw data and pre-processed files are written to 9 track tape.  The data 
is later transfered from tape to Exabyte cartridge using the VAX/VMS Backup 
utility.  These cartridges contain all the raw data collected during a cruise 
and are permenantly archived.

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 
Fr7/92 (09FA0792).
=========================================================================

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 P115 (Cond Ratio: 0.99986).  
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) 


Miscellaneous
=============

The sounder used a sound speed of 1500metres/second for this and all 
subsequent cruises.


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

        Fr7/92         Townsville - Brisbane       19 Sep - 6 Oct 1992


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

	John Church         Chief Scientist        CSIRO DO
        Fred Boland         Moorings/CTD watch     CSIRO DO
        Kevin Miller        Moorings/CTD watch     CSIRO DO
        Danny McLaughlin    Moorings/CTD watch     CSIRO DO
        Neil White          CTD watch              CSIRO DO
        Val Latham          Nutrients/Salts/DOs    CSIRO DO
        Mark rayner         Nutrients/Salts/DOs    CSIRO DO
	Phil Adams          Electronics            CSIRO DO
        Graham Jones        DMS                    James Cook University
        Mark Curran         DMS                    James Cook University


References
==========

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




