                           NAVAL HYDROGRAPHIC SERVICE

                           DEPARTAMENT OF OCEANOGRAPHY
                            Technical Bulletin N° 72


                      CTD AND XBT PHYSICAL-CHEMICAL DATA,
                             OCEANOGRAPHIC CRUISES:

                              CAP.OCA BALDA 04-91
                             (WOCE ARO8_08BD0431_1)

                         DR. EDUARDO L. HOLMBERG 04-92
                             (WOCE AR08_08EH0492_1)

                               EL AUSTRAL 01-92
                             (WOCE ARO8_08EA0192_1)


   Ana P. Osiroff, Marcela Charo, Alberto R. Piola and Alejandro A. Bianchi

 
August, 1993
ARMADA ARGENTINA 



1. INTRODUCTION 

Researchers from the Hydrographic Naval Service (SIHN) are working on a project called 
Contour Streams of the South-Occidental Atlantic as an Argentinean contribution to the 
World Ocean Circulation Experiment (WOCE, see Piola and Bianchi, 1992). The WOCE 
observational phase consists on annually elaborating two oceanographic sections in the 
38°S vicinity. The project was initiated September 1991 and will continue until 1996.

The data from the oceanographic cruises that will be presented in this report, have been 
collected during the time margin for this project. The cruises are: BIP Captain Oca Balda 
04/91 (OA-0491), BIP Dr. Eduardo L. Holmberg 04/92 (HO-0492) and BIO El Austral 01/92 (AU-
0192).

The observational phase for the cruise consists on conducting periodic testing of the 
synoptic situation on the Brazil/Malvinas confluence. On each section, a series of 
oceanographic stations will be conducted, this includes continuous pressure, temperature 
and conductivity profiling and discrete sampling of salinity, temperature, dissolved 
oxygen and nutrients. These stations are transversal to the continental talus and are 
wide-ranging enough  to reach the Brazilian stream3.  

The objective of defining the thermohaline characteristics from the denominated Talus 
Front has been added to this project. Such front will accomplish a fundamental roll in the 
maintenance of the high primary productivity of the region and is in the interest of other 
projects by the National Institute for Fishing Investigation and Development (INIDEP).  
The field work includes elaborating transversal cuts to the front and repeated outlining 
(yo-yo stations) to pressure, temperature and conductivity. 

This report will present physical-chemical data and CTD from the oceanographic cruises OA-
0491 (Figure 1), HO-0492 (Figure 2) and AU-0192 (Figure 3).  Also included are data from 
bathythermographs (XBT) carried out during the HO-0492 cruise. 


2. DATA ACQUISITION SYSTEM 

On the three cruises presented in this report a continuous pressure, temperature and 
conductivity (CTD) profiler was used type NBIS MKIII B brand name Neil Brown Instrument 
Systems.

The water samples were obtained with a rosette, brand name General Oceanics containing 
twelve Niskin bottle samples of 5lt each.  Six bottles were equipped with protected and 
unprotected reversing thermometers for determining the in-situ temperature and 
thermometric depth. The rosette is installed on the CTD at approximately 120cm from the 
sensors. This configuration allows us to obtain CTD pressure, temperature and conductivity 
calibration values from each station and water samples for future chemical analysis. 
Collecting the CTD data was done by a personal computer (PC) that uses the Oceansoft Mark 
III Acquisition  "MK3ACQ" software from EG&G Marine Instruments, which provides lists, 
plots and storage of real time data, allowing room for preliminary processing and 
evaluation of the quality of the data on board. 


3   WATER AND THERMOMETER SAMPLES 
3.1 Description
 
Water samples from each oceanographic station were obtained for the purpose of calibrating 
the CTD data and determining the concentration of dissolved oxygen and nutrients. The data 
from the reversing thermometers installed on six of the bottles on the rosette, were used 
to determine in-situ temperature and depth. The thermometers used were calibrated on the 
Hydrographic Naval Service Laboratories' grounds. The conductivity of the water samples 
was determined with a salinometer brand name Plessey model 6230N, standardized with normal 
water from Wormley (Partida P118 – Nov. 1991). Salinity was calculated with the Practical 
Salinity Scale from 1978 (UNESCO, 1981). The dissolved oxygen was determined with a 
modified Carpenter (1965) technique. On the HO-0492 and AU-0192 cruises, the water samples 
for determining the nutrients were frozen on board to -20(C for future analysis in the 
laboratory. These samples were analyzed in the National Institute for Fishing 
Investigation and Development, using the Grasshoff et al. Method (1983). 

Table 1 

Water Samples, parameters determined per cruise

Cruise  | Analyzed Parameters                          | # Of Samples
---------------------------------------------------------------------
OA-0491 | SALNTY OXYGEN SILCAT, NITRIT, NITRAT, PHSPHT |     156
HO-0492 | SALNTY OXYGEN SILCAT, NITRIT, NITRAT, PHSPHT |     158
AU-0192 | SALNTY OXYGEN SILCAT, NITRIT, NITRAT, PHSPHT |     118



3.2 QUALITY CONTROL

The quality control for the water samples was carried out considering two aspects:

a) Systematic comparison between pressure, temperature and salinity data from 
   the rosette was measured simultaneously with the CTD.

   Differences between the data from the rosette and the CTD were calculated. 
   The calibration of the CTD observations, which are further described below, 
   is based on determining the polynomial that best fits the differences 
   observed between the CTD and the rosette data. The rosette data that exceeds 
   the two standard deviation differences allowed for the corresponding 
   calibration curve are considered doubtful and are not used for the 
   calibration.

b) Historical Data Comparison:
   For each cruise the potential temperature distribution was compared vs. 
   salinity, dissolved oxygen, silicates, nitrites and phosphates with the same 
   distributions based on high precision historical data.  The contrast was 
   carried out for potential density anomalies of 27.25 and 27.50. Data from the 
   following cruises were used: Atlantis II-107-3 (Guerrero et al. 1982), 
   Atlantis II-107-10 (Piola et al., 1981), Marathon 7-1984 (Camp et al., 1984), 
   Save V-1998 (Scripps Institute Of Oceanography 1989), Geosecs 6-1981 (Geosecs 
   Atlantic Expedition-Vol.1, Bainbridge A., 1981), Puerto Deseado 02-88 and 
   Confluencia 89 (Charo et al, 1991).

   The comparison between the dissolved oxygen, nutrients, salinity and 
   temperature data from the three cruises with the historical data is 
   summarized on tables 2 and 3. The tables show the median of every variable  
   over the two isopycnal surfaces: Sigma sub theta = 27.25 and Sigma sub theta 
   = 27.50.

Table 2: Dissolved oxygen, nutrients, salinity and temperature potential for 
         Sigma sub theta = 27.25
 
Potential density anomaly (kg/m3)|  Sigma sub theta = 27.25
---------------------------------|-----------------------------
 Cruise     |  O2  | SiO3 | NO3  | NO2  | PO4  | Theta |  S 
 -----------|------|------|------|------|------|-------|-------
 AII-107-3  | 5.71 | 27.1 | 28.6 | 0.02 | 1.98 | 3.338 | 34.224
 AII-107-10 | 5.57 | 35.1 | 29.9 | 0.05 | 2.09 | 3.275 | 34.208
 MARATHON 7 | 5.48 | 29.8 | 27.3 | 0    | 1.93 | 3.708 | 34.291
 SAVE 5     | 5.56 | 29   | 30.3 | 0.01 | 2.07 | 3.352 | 34.245
 GEOSECS 6  | 4.98 | 26.7 | 30   |      | 1.99 | 4.093 | 34.29
 PD-0288    | 5.51 | 36.4 | 24.1 | 0.19 | 1.89 | 3.004 | 34.203
 CONF 89    | 5.4  | 33.5 | 32.2 |      | 2.33 | 3.582 | 34.278
 OA-0491    | 5.89 | 23.4 | 20.5 | 0.05 | 1.89 | 3.103 | 34.217
 HO-0492    | 5.65 | 33   | 27.1 | 0.03 | 2.23 | 3.32  | 34.242
 AU-0192    | 5.83 | 24.7 | 26.1 | 0    | 1.68 | 3.023 | 34.207



Table 3: Dissolved oxygen, nutrients, salinity and temperature potential for 
         Sigma sub theta = 27.50

Potential density anomaly (kg/m3)|  Sigma sub theta = 27.50
---------------------------------|-----------------------------
 Cruise     |  O2  | SiO3 | NO3  | NO2  | PO4  | Theta |  S 
 -----------|------|------|------|------|------|-------|-------
 AII-107-3  | 4.43 | 54.2 | 31.9 | 0    | 2.21 | 2.768 | 34.475
 AII-107-10 | 4.47 | 62   | 33.3 | 0    | 2.31 | 2.547 | 34.44
 MARATHON 7 | 4.44 | 52.1 | 30.4 | 0    | 2.1  | 3.014 | 34.521
 SAVE 5     | 4.35 | 57.9 | 33.5 | 0.01 | 2.29 | 2.704 | 34.484
 GEOSECS 6  | 4.33 | 52   | 33.1 |      | 2.23 | 2.818 | 34.452
 PD-0288    | 4.36 | 65   | 30.3 | 0.11 | 2.36 | 2.593 | 34.467
 CONF 89    | 4.55 | 52.2 | 33.9 |      | 2.45 | 2.827 | 34.497
 OA-0491    | 4.45 | 49.9 | 21.1 | 0.05 | 2.04 | 2.724 | 34.487
 HO-0492    | 4.92 | 50.1 | 31.9 | 0.08 | 2.13 | 2.866 | 34.503
 AU-0192    | 4.28 | 40.1 | 25.9 | 0    | 1.62 | 2.589 | 34.472
 
 

4.  PROCESSING THE CTD
4.1 Response time from the sensors


The performance of a latest model CTD is a function of the precision of the sensors and 
the testing frequency. The testing frequency is limited by the response time from the 
sensors to temperature changes. The temperature measurements, in particular, are affected 
even on the fastest sensors (response time is approximately 250ms), an unacceptable 
inertia for a correct salinity calculation. 

On some CTD's this deficiency is partially compensated by combining a quick response 
thermistor with a high stability thermometer. Unfortunately, this configuration requires 
an extremely precise adjustment of the electronics associated and could not be 
accomplished for the purpose of these cruises. For this reason, the thermistor was 
eliminated and only the platinum thermometer was used. As a consequence of the thermal 
inertia from the thermometer, there are spurious inversions in the density associated with 
salinity errors.  With the purpose of minimizing this inconvenience, a recursive 
exponential filter was applied in the form:

          C(t) = C (t - ( t) Wo  + Ci W1                  (4.1)
where Wo = e -delta t/gamma
                             W1 = 1 -Wo,

where gamma is the constant for the platinum thermometer time, delta t is the testing 
interval from the CTD (approximately 0.032 seconds for the Mark IIIb), C filtered 
conductivity and Ci the unfiltered conductivity. The filter must produce an effective 
conductivity delay comparable to the effects of the thermal inertia quality in a 
thermometer. Determining the delay to be applied is based on the maximum correlation 
between the conductivity and temperature perturbations. The delay obtained for the three 
cruises by this method was 6 units, which is equivalent to about 200ms. . 


4.2 Data Editing

The first step in the CTD data processing is editing. For this, with the cooperation of 
the programming analyst Alfred Rolla from the Argentinean Center for Oceanographic Data 
(CEADO), an editing program was developed that allows for an analysis of raw pressure, 
temperature and conductivity. It detects spurious values of such parameters by comparing 
the differences between the previous values and the current value with a degree of 
tolerance for each one and a precision range according to the characteristics of the water 
column. If the difference exceeds the given value, the data is considered questionable and 
is assigned a mark that will allow the upcoming programs to ignore that data. 
	

4.3 Standardization of the Series

For the second step, the edited data are averaged and calibrated to generate a series of 
temperature and conductivity data at uniform pressure intervals.  First a filter is 
applied that eliminates the difference in the sensor response time (Ec. 4.1) and converts 
the raw data into an averaged pressure series. In general, the resulting series does not 
have a constant pressure interval due to the fact that the velocity while lowering the 
instrument is not uniform. The following is the temperature and conductivity calibrations 
that generate a series of data at 2 decibar intervals. 

4.4 Calibration

The pressure, temperature and conductivity sensors are calibrated in a sequential form in 
that order. The applied corrections are in general, functions of pressure but in some 
instances could also depend on temperature and conductivity.

In general, the pressure and temperature calibrations have the following form:

               Pc = Pm + P0 + P1Pm + P2P2m + .....+PnPnm
                 Tc = Tm + T0+T1Pm + T2P2m + .....+TnPnc

Where Pc and Tc are corrected pressure and temperature; Pm and Tm are the measured 
variables; Pi and Ti are the polynomial calibration coefficients with the superscript 
variable meaning the order of the applied calibration. 

The calibration coefficients were obtained by using the least squares method. The order of 
the approximation polynomials was chosen to try to minimize the standard deviations. 


Conductivity Calibration

Conductivity calibration is done in the laboratory, it transforms the conductivity 
measured by the CTD (G) at conductivity C, taking into consideration the deformation of 
the materials in the chamber that is proper to each instrument. For the CTD NBIS/EG&G Mark 
IIIb, the conductivity is

                 C = G (1 + ( (T - T0) + ( (P - P0))

Where  
alpha = -6.5 E-6 °C
beta  =  1.5 E-8dbar
Tau o =  2.8 °C
Po    =  3000dbar

P, T and G are pressure, temperature and conductance measured by the CTD.

A procedure of iterative adjustment has been applied to obtain conductivity coefficients 
that allow us to eliminate spurious data. 

The differences between the data from the water samples and the corresponding CTD are 
estimated. The coefficients from the conductivity sensors are adjusted (in a way that the 
sum of the squares of these differences are minimized) using the least squares method.

The differences between the data of each of the water samples and the corresponding data 
from the sensors, are verified by an editing criteria of the form  sigma x F that involves 
the standard deviation by an F factor. It is chosen so the probability of eliminating 
valid observations is minimized.  For a normal distribution, a value of F=2.8 implies that 
the probability of eliminating valid observations is 0.5%. After extracting the bad 
values, the rest of the data is readjusted in a similar way until all the values that are 
not in the criteria are eliminated. 

To calibrate the CTD conductivity sensor, the salinity from the water samples is converted 
to in-situ conductivity Cw. 

As we mentioned previously, the CTD conductivity is corrected by the deformation of the 
materials in the chamber. We must also consider the drift that exists within the stations 
due to the filth on the sensor and washing every station afterwards. Finally, the 
conductivity is

                               Cm=G(A+B*SN)+C

A and C are the calibration coefficients and B is the conductivity adjustment that depends 
on the station multiplied by the station number SN. This factor B is optional and is not 
considered in the data processing for these cruises.
The coefficients, are obtained in a way to minimize the variance (2 defined as

                              sigma 2=1/N*Sigma(Cw-Cm)2

where Cw is the conductivity of the water sample. 

To determine the values that are considered bad and eliminate them, we apply the following 
test in which factor F (described previously) is taken into consideration such that
                              | Cw - Cm | > F.sigma

On the OA-0491 cruise, pressure was calibrated as a function of a linear dependency to the 
uncorrected pressure (Pi):

                              Pc = Ap + Bp * Pi

Pc is the corrected pressure.

This calibration lead to a conductivity correction also linear dependant on pressure. This 
conductivity dependency with pressure is unjustifiable from a physical point of view. 
Therefore, pressure re-calibration proceeded as a function of a constant factor, meaning, 
independently from pressure. 

                               Pc = Ap + Pi

The conductivity calibration that resulted from the new pressure calibration is weakly 
dependant on pressure. As a consequence, this methodology was used for al the cruises. 

Station 6 from cruise AU-0192 was independently calibrated from the rest of the stations, 
this is because in the joint calibration there existed a 0.03 psu difference between the 
salinity value from the CTD and the value from the bottles. 

See table 4, 5 and 6. 


Table 4:  Calibration Coefficients from the CTD Cruise OCA BALDA 04-91

                     Coef 0   Coef 1  Standard deviation  Data Number
---------------------------------------------------------------------
Pressure * (dbar)   -1.7                    1.40              13
Temperature (°C)     0.0303   0.013                           52
Conductivity (mmho)  0.05359  0.9985        0.003            113

(*) Promedio del valor de cubierta


Table 5:  Calibration Coefficients from the CTD Cruise DR. E. HOLMBERG 04-92

                     Coef 0   Coef 1  Standard deviation  Data Number
---------------------------------------------------------------------
Pressure (dbar)     -1.9372                 5.39              78
Temperature (°C)     0.0275                 0.063             84
Conductivity (mmho)  0.04271  0.9988        0.004             53


Table 5
Calibration Coefficients from the CTD CRUISE EL AUSTRAL 01-92 (*)

                               Coef 0    Coef 1  Standard deviation  Data Number
--------------------------------------------------------------------------------
Temperatura (dbar)             0.0377                  0.024            35
Conductivity (mmho)            0.07691   0.9984        0.002           114
Conductivity station 6 (mmho)  0.04065   1.0003        0.003            12 

(*)The pressure was calibrated according to the cover value according to each 
   station.


Figures 4, 5 and 6 show the residual distributions of the difference between the 
parameters measured with the CTD and the corresponding water samples as a function of 
pressure for each cruise.

Figures 4.a and 4.b:  Temperature and Conductivity residuals as a function of 
                      pressure for cruise OA-0491.

Figures 5,a, 5.b and 5.c:  Pressure, Temperature and Conductivity residuals as a 
                      function of the pressure for HO-0492.

Figures 6.a and 6.b:  Temperature and Conductivity residuals as a function of 
                      the pres-sure for the cruise AU-0192.


5. XBT Data

Table 7 shows information referring to bathythermograph launchings that can be dismissed. 
They were carried out for cruise HO 04-92, these positions are noted in figure 2. The XBT 
data were manually digitalized from the results.

Table 7:  XBT Information; Cruise DR. E. HOLMBERG 04-92

XBT| Fecha    | GMT   |   Lat   | Long    |T-Seco|T-Húm.|V-Dir| V-Vel| P.Atm.
 # |          |       |   (S)   | (W)     | (°C) | (°C) |     |nudos | (mbar)
---|----------|-------|---------|---------|------|------|-----|------|-------
 1 | 09/05/92 | 20:17 | 39 16.3 | 55 19.8 | 15.5 | 14.5 | 065 | calma| 
 2 | 10/05/92 | 00:08 | 39 24.2 | 55 06.3 |      |      | 090 |  8.0 | 
 3 | 10/05/92 | 02:51 | 39 30.9 | 54 58.6 |      |      |     |      | 
 4 | 10/05/92 | 10:20 | 39 34.2 | 54 51.4 | 17.0 | 16.2 | 070 | 15.0 | 1013.5
 5 | 10/05/92 | 11:18 | 39 37.9 | 54.39.9 | 16.6 | 15.9 | 070 | 15.0 | 1013.5
 6 | 10/05/92 | 15:08 | 39 42.5 | 54 27.9 |      |      |     |      | 
 7 | 10/05/92 | 16:12 | 39 45.4 | 54 17.2 |      |      |     |      | 
 8 | 11/05/92 | 01:03 | 40 07.0 | 53 43.7 |      |      |     |      | 
 9 | 11/05/92 | 02:55 | 40 11.1 | 53 30.6 | 16.0 | 16.0 | 060 | 30.0 | 1012.0
10 | 11/05/92 | 10:19 | 40 34.2 | 54 01.4 | 18.2 | 18.0 | 050 | 12.0 | 1010.5
11 | 11/05/92 | 13:59 | 40 59.4 | 54 42.6 | 16.8 | 16.5 | 050 | 10.0 | 1009.0
12 | 11/05/92 | 17:30 | 41 18.7 | 55 28.6 | 15.5 | 15.0 | 090 | 11.0 | 
13 | 11/05/92 | 21:00 | 41 40.9 | 56 12.6 | 14.5 | 14.1 | 060 | 26.0 | 1001.3
14 | 12/05/92 | 00:48 | 42 04.2 | 56 58.3 | 13.4 | 13.0 | 060 | 15.0 |  998.0
15 | 12/05/92 | 04:31 | 42 26.4 | 57 41.0 | 11.0 | 10.5 | 270 |  4.0 |  997.5
16 | 12/05/92 | 08:25 | 42 49.1 | 58 24.6 | 10.2 | 10.0 | 080 | 10.0 |  994.5
17 | 12/05/92 | 12:26 | 43 12.5 | 59 09.1 | 10.0 | 10.0 | 060 | 10.0 |  993.0


6.  Presenting the Data
6.1 Water Samples

The data from the water samples are presented along with the calibrated CTD information on 
the instance of the closing of every bottle.  For each station the following parameters 
are presented:

CTD

PR:  Pressure in decibars. 
TE:  Temperature in (C.
SAL: Salinity in Practical Units (UNESCO, 1981a and 1983).
TP:  Potential temperature in (C (Bryden, 1973).

ROSETTE

TE-ROS: Temperature in °C.
SAL:    Salinity in Practical Units (UNESCO, 1981a).
O2:     Dissolved Oxygen concentration in ml./l.
SiO4:   Silicate concentration in (mol/kg.
NO3:    Nitrate concentration in (mol/kg.
NO2:    Nitrite concentration in (mol/kg.
PO4:    Phosphate concentration in (mol/kg.

The temperature and salinity values from the bottles were plotted as vertical profiles for 
each station. Also presented for each cruise are salinity and nutrient plots as a function 
of potential temperature. 


6.2 CTD

For every station a graphical representation of the vertical distributions of potential 
temperature, salinity and potential density anomalies was presented. This last variable is 
calculated using the algorithm for the equation for the state of the sea water given by 
Millero and Poisson (1981). Some stations had differences between the values from the 
bottle and the corresponding CTD profile, due to the variation observed between ascent and 
descent, reason why both profiles are presented. 

The profiles from the yo-yo stations for cruises OA-0491 (OA04D401-415) and HO-0492 
(Ho04D040-054) and the high resolution legs from cruises Oa-0491 (OA04D120-129) and AU-
0192 (AU01D010 and AU0120-128) are constructed in the following manner: the first profiles 
for temperature, salinity and anomalies in the potential density coincide with the scale 
from the corresponding axis, the resulting ones are translated sequentially at 1(C, 0.25 
ups and 0.5 kg/m3 from the previous one. 

A table containing predetermined levels of CTD data and a header contains the following 
information:

* Ship Code:  OA (Oca Balda), HO (Dr. Holmberg) and AU (El Austral). 
* Date:       day, month and year.
* Time:       GMT.
* Latitude and longitude in degrees, minutes and hundredths of the minute from 
              the beginning of the station. 
* Gravity
* Coriolis Parameter
* Sonic depth
* SAL:        Salinity in Practical Units (UNESCO, 1981a and 1983).
* TPOT:       potential temperature in (C (Bryden, 1973).
* SIGTH:      density anomalies  in kg/m3 (UNESCO, 1981b).
* SIG2, SIG4: potential density anomalies at pressures of 2000 and 4000 dbar 
              in kg/m3 (UNESCO, 1981b).
* ALTDIN:     Dynamic height at 101 J/Kg.
* PE:         Potential energy anomalies at 105 J/m2 (Fofonoff, 1962).
* GRDTP:      Vertical gradient for potential temperature ((T2) at 103 (C/dbar.
* GRDS:       Vertical gradient for salinity ((S2) at 103/dbar.
* TASADENS.:  Density rate (R(((((((((((S2)
* BV:         BruntVaisala in cycles/hour (Fofonoff, 1985).
* PROF:       depth in meters (Saunders and Fofonoff, 1976).


6.3 XBT

The XBT data presented in this report contains lists and plots for temperature as a 
function of the  depth  for each launching. The plots are constructed in the following 
way: the first thermal profile coincides with the temperature scale from the corresponding 
axis, while the rest are sequentially displaced 1(C from the previous one. The lists 
present temperature values at variable  depth intervals, for different portions from the 
water column.  



7    DATA QUALITY EVALUATIONS
7.1  NOTES FOR REPORT TO WHP PROGRAMME OFFICE ON DQE WORK ON NUTRIENT DATA FROM AR08
     (L. Gordon)
     Feb 6, 1997

GENERAL OBSERVATIONS:

1. The region is highly energetic, displaying considerable variability from cruise to   
   cruise and from place to place. One could expect the influences of large, regional 
   rivers and seasonal variability of the biota to affect the near-surface samples. The 
   mesoscale or larger variability of the Deep Western Boundary Current would increase 
   variability of the deep samples. Note that all of the Ar08 cruises lay on the 
   continental shelf and slope where these effects would be most apparent.

2. We compared the Ar08 data with that from the SAVE cruise LG5. (March, ca. three degrees 
   latitude to the north and similarly located on the shelf and slope) The SAVE data 
   showed much smoother vertical profiles and much less scatter in the variable-variable 
   plots, eg. nitrate:phosphate than for the Ar08 data. We also note that Ar08 cruise 
   EH492 (May, late autumn) displays considerably less scatter than do the BD491 and EA192 
   legs in September and October (late spring) indicating a seasonal influence on observed 
   variance.

3. We note that within ca. 5% or so, the phosphate:nitrate plots for the three Ar08 
   cruises are parallel to the similar plot for the SAVE leg. This indicates that the 
   calibrations of the sensitivities of the analyses were internally consistent.  That is, 
   the calibration standards used were within ca. 5% of being either correct, or of having 
   similar systematic errors.

4. Because of the high variability to be expected close inshore in shallow water, we did 
   not for the most part question the data from the three most inshore stations. We noted 
   some deep samples that did not follow the general trends and they are noted later.

5. The phosphate data exhibit the most problems with many high, questionable values. The 
   nutrient data in general do not appear to meet the WOCE specifications of precision.

6. All of the samples for which we make specific comments have been flagged as 
   questionable.


SPECIFIC COMMENTS:

Cruise/Sta |Notes
-----------|------------------------------------------------------------------------------
BD491| All |All of the nitrite values from depths greater than 500 db, indicate a bias of 
     |     |ca. +0.05 micromolar and thus all the nitrite data are probably biased by this 
     |     |amount.
BD491|   3 |The nitrite values for this station appear high but we do not have strong 
     |     |evidence to flag them as questionable. This was a shallow inshore station.
BD491|5,6,7|The nitrate:phosphate plot displays an offset by these three stations compared 
     |     |with the others before and after. This could be a real effect of differing 
     |     |preformed phosphate or nitrate or both for these three stations from the 
     |     |others.
BD491|   7 |Phosphate at 1140 db appears high based on P:N and vertical profile.
BD491|   8 |Two phosphate values are questionable. The 8.4 db and 303.8 db values appear 
     |     |to be high based on P:N and the vertical profile. The nitrite value at 
     |     |303.8 db appears to be high. All nutrients at 1010.8 db appear to be high.
BD491|   9 |The 1006.2 db phosphate appears to be high based on P:N and vertical P 
     |     |profile. The next two shallower samples, 813.8 and 602.4 db, appear to be bad. 
     |     |All nutrients and oxygen indicate that the samples came from shallower depths, 
     |     |either pre- or post-tripped. The nitrite value at 203 db is high.
BD491|  10 |The SUM file indicates that there was a cast taken. However the *.LIG files we 
     |     |received did not include bottle data for this station
EH492|   3 |Three deepest bottles, 54.7-89.1 db, do not follow the trend of the 
     |     |neighboring stations in nitrate:phosphate, or vertical profile. However, these 
     |     |samples came from a sharp nutricline, oxycline and thermocline. The phosphate 
     |     |data could perhaps be OK, but we flag them as questionable because of the P:N 
     |     |plot.
EH492|   5 |The nitrite value at 845.4 db appears to be high.
EH492|   7 |The deepest seven phosphate numbers appear to be high by ca. 20%, derived from 
     |     |the phosphate:nitrate, phosphate:oxygen plots and the phosphate vertical 
     |     |profile. The nitrite values below 250 db with the possible exception of the 
     |     |value at ca. 1400 db appear to be high. It is possible that all of the nitrite 
     |     |data from this station are biased by ca. + 0.05 micromolar or somewhat more.
EH492|   8 |The water sampler at 656 db apparently leaked or closed at the wrong depth. 
     |     |The nitrite values at 656 and 1607.5 db appear to be high. All of the nitrite 
     |     |values appear to biased by +0.02 micromolar as shown by the deep numbers. We 
     |     |are in somewhat of a quandary regarding some of the shallower silicate data. 
     |     |We have flagged them as high but see the comment for station 10.
EH492|   9 |The phosphate data for this station were apparently inverted with respect to 
     |     |depth. When we replotted the phosphate data versus depth after inverting the 
     |     |phosphate values the vertical profile appeared to be more acceptable. We 
     |     |therefore flagged all of the phosphate data for this station as questionable 
     |     |but the depth inversion should be noted in the cruise report because the data 
     |     |originator may be able to salvage these data. The nitrite value at ca. 1297.7 
     |     |db appears to be high.
EH492|  10 |The eight deepest samples display relatively high silicate values in the 
     |     |theta:silicate plot and in the vertical profile. They also appear high 
     |     |compared to the regional, SAVE data. We flag them as questionable.  However, 
     |     |they do agree well with the silicate data at station 8 over the common depth 
     |     |range except for the two or three deepest samples at station 8.
EH492|  54 |The nitrite data are scattered with many erratic high values. The values at 
     |     |ca. 260.3 and 371 db are quite high and may indicate that all the data are 
     |     |biased by ca. +0.07 to +0.08 micromolar.
EA192|   5 |Except for nitrite, the deepest five samples exhibit vertical nutrient 
     |     |profiles off the main trend lines for the section.  The vertical profiles for 
     |     |these samples are similar to station 11, the farthest offshore, six stations 
     |     |away.
EA192|   7 |The 1201.1 db sample seems to have been a bad sample for all nutrients. It 
     |     |falls off the trend line for P:N and is off the probable vertical trends for 
     |     |P, N and Si. The entire deep part of the profile exhibits an amount of 
     |     |scatter, range of ca. 10% or more of the deep values for P, N and Si.
EA192|  11 |This entire station looks funny for temperature, oxygen, all nutrients and 
     |     |maybe salinity. Are the depth data are incorrect?



7.2  DQE OF CTD DATA FOR THE 1991 CRUISE OF THE R/V "CAPTAIN OCA BALDA", 1992 CRUISE OF 
     THE R/V "EL AUSTRAL" AND 1992 CRUISE OF THE R/V "DR. EDUARDO HOLMBERG" WOCE SECTION 
     AR08 IN THE SOUTH ATLANTIC.
     (Eugene Morozov)
     May 8, 1995

Data quality of 2-db CTD temperature and salinity profiles and reference rosette samples 
w-Ith oxygen measurements were examined. Vertical distributions and theta-salinity curves 
were compared for individual stations using the data of up and down CTD casts and rosette 
probes. Data of several neighboring stations were compared. The data from all three of the 
cruises were also compared.

Questionable data in *.hy2 file were marked in QUALT2 word.

The calibration of upcast and downcast CTDSAL, data seem to be correct. I have minor 
remarks concerning several bottle SALNTY measurements which seem to be questionable..


SALINITY DATA (Only those stations are listed which have data remarks)

CAPITAN OCA BALDA CRUISE
Sta | Pres    | Remarks
----|---------|--------------------------------------------------------------------------
  3 | 20.9 db | CTDTMP is low (6.958) compared with downcast CTDTEMP, and due to this 
    |         | temperature the measurements fall from the theta-S curve. 
  3 | 40.4 db | CTDTMP is low (4.725) compared with downcast CTDTMP, and due to this 
    |         | temperature the measurements fall from the theta-S curve.
  5 | 392 db  | SALNTY (34.168) is high compared with upcast CTDSAL (34-164) and Downcast 
    |         | CTDSAL (34.165), flag 3. 
    | 449 db  | SALNTY (34-179) is high compared with upcast CTDSAL (34.172) and Downcast 
    |         | CTDSAL (34.165), flag 3
  6 | 695 db  | SALNTY (34.197) is high compared with upcast CTDSAL (34.192) and Downcast 
    |         | CTDSAL(34.194), flag 3
    | 805 db  | SALNTY (34.205) is high compared with upcast CTDSAL (34.198) and downcast 
    |         | CTDSAL (34.198), flag 4.


OXYGEN DATA 

There were more problems with the oxygen data.  Repeated bottle OXYGEN measurements made 
at close levels differ sometimes by 1-5 mol/kg, which makes me think that OXYGEN 
determination in the cruise was not made with a required accuracy.  I flag 4 (bad) the 
following repeated samples:

Station 1 | 80.9 db | sample 3 | high OXYGEN (278.9) | flag 4 
Station 2 | 78.1 db | sample 1 | high OXYGEN (287.6) | flag 4
Station 2 | 78.4 db | sample 6 | high OXYGEN (288.0) | flag 4



There are some more bottle OXYGEN data that do not match with the vertical distributions 
and theta-oxygen curves:

Sta |  Pres  | Remarks  
----|--------|-------------------------------
  2 |   21.4 | High OXYGEN | (342.4) | flag 3
  3 |   30.3 | High OXYGEN | (313.3) | flag 3
  3 |   50.5 | High OXYGEN | (294.0) | flag 3
  3 |   30.3 | High OXYGEN | (313.3) | flag 3
  6 |    9.2 | High OXYGEN | (313.3) | flag 3
  6 |   19.2 | High OXYGEN | (313.3) | flag 3
  6 |  198   |  Low OXYGEN | (270.0) | flag 3
  6 |  603   | High OXYGEN | (279.0) | flag 3
  6 |  893   | High OXYGEN | (266.0) | flag 3
  9 |  602   | High OXYGEN | (302.6) | flag 3
  9 |  813   | High OXYGEN | (298.2) | flag 3
  9 | 1722   | High OXYGEN | (183.8) | flag 3
 10 | 1027   | High OXYGEN | (252.2) | flag 3


EL AUSTRAL CRUISE

Downcast CTDSAL and SALNTY measurements on station 1 coincide only at the bottom level.  
The difference at the surface level is as much as 0.1 PSU. What is this - bad calibration 
or a coastal front?




Station 5 | 599 db | low salinities, the differences with the upcast CTDSAL are
            697 db | acceptable but they do not match with Theta S curve and vertical 
                   | distribution.  It may possibly be an intrusion of different water but 
                   | I flag both salinities 3 - Qble

Repeated bottle OXYGEN measurements made at close levels on STATION 6 differ, sometimes by 
5 mol/kg, which makes it difficult to determine which of the samples is correct.

BOTTLE OXYGEN data that do not match with the vertical distributions and theta-oxygen 
              curves:

Sta | Pres  | Remarks  
----|-------|---------------------------------------------------------
 1  |   7.5 | High OXYGEN | (379.2) | flag 4 | ( 7.9 db | 352.6 -norm)
 1  |  17.4 | High OXYGEN | (330.8) | flaq 4 | (17.3 db | 312.5 -norm)
 1  |  34.  | High OXYGEN | (319.9) | flag 3 | 
 6  | 197   | Low OXYGEN  | (278.3) | flag 3 | 
 6  | 402   | Low OXYGEN  | (253.0) | flag 3 | 
 7  | 293   | Low OXYGEN  | (237.8) | flag 3 | 
 7  | 499   | High OXYGEN | (292.1) | flag 3 | 



DR. EDUARDO HOLMBERG CRUISE

Station 6 | 298 db  | Low SALNTY (34.11).  It matches with upcast CTDSAL, but is much 
          |         | lower than downcast CTDSAL (34.333) and. does not fit the THETA-S 
          |         | curve.  It may possibly be intrusion, but I flag it  "3".
          | 598 db  | High SALNTY (34.211).  It exceeds both the upcast CTDSAL (34.17) and 
          |         | downcast CTDSAL (34.17), flag  "4".
Station 2 |  28 db  | High OXYGEN (265.8), flag "3" 
Station 7 | 997 db  | High OXYGEN (266.9), flag "3"



Acknowledgements

The project Contour Streams of the South-Occidental Atlantic was financed by the 
Hydrographic Naval Service. Publication costs for this report were also covered by SIHN. 
The Argentinean Antarctic Institute  loaned a CTD system Neil Brown MKIII B to be used on 
the three cruises. SMARA, in particular engineer Hector Salgado, cooperated with this 
project by processing satellite images provided by the AU 01-92 cruise. Digitalization of 
the XBT was done by Gerardo Collino.

The authors thank engineer Robert Millard from the Woods Hole Oceanographic Institution 
for his cooperation in adapting post-processing programs for the CTD. These programs were 
given to our project group. Finally, we acknowledge the people who participated in the 
cruises and the crew aboard the BIP "Capitan Oca Balda", BIP "Dr. . Holmberg" and BIO "El 
Austral". Their collaboration, dedication and professionalism contributed greatly to the 
success of the observational phase of the project. 


PARTICIPANTS 

OCA BALDA 04-91
Name                    Institution     Specialty
------------------------------------------------------------
Piola, Alberto          SIHN            Jefe Científico
Guerrero, Raúl          INIDEP          Co-J.Cient./Resp.CTD
Arraga, Etelvina        SIHN            Oxígeno disuelto
Baldoni, Ana            INIDEP/CONICET  CTD
Bazán, José             SIHN            Oxígeno disuelto
Bianchi, Alejandro      SIHN            Responsable CTD
Carignan, Mario         INIDEP          Nutrientes
Ehrlich, Martín         INIDEP          Zooplancton
Framiñan, Mariana       SIHN            CTD
Giulivi, Claudia        SIHN/CONICET    CTD
Machinandiarena, Laura  INIDEP          Zooplancton
Mianzán, Hermes         INIDEP/CONICET  Zooplancton
Negri, Rubén            INIDEP          Fitoplancton/mat.susp.
Osiroff, Ana            SIHN/CONICET    Salinidad
Pascucci, Claudio       SIHN            CTD/Electrónica
Tosonotto, Gabriela     IAA             CTD
Vetere, Fabián          SIHN            CTD

DR. EDUARDO HOLMBERG 04-92
Name                    Institution     Specialty
------------------------------------------------------------
Piola, Alberto          SIHN            Jefe Científico
Arango, José            CONICET         CTD
Balestrini, Carlos      SIHN            CTD
Bianchi, Alejandro      SIHN            Responsable CTD
Carignan, Mario         INIDEP          Nutrientes disuelto
Charo, Marcela          SIHN            CTD
López, Fernando         INIDEP          Electrónica
Negri, Rubén            INIDEP          Fitoplancton/mat.susp.
Osiroff, Ana            SIHN/CONICET    Salinidad
Quiroga, Pedro          INIDEP          Salpas
Sik, Enrique            SIHN            Oxígeno disuelto
Tosonotto, Gabriela     IAA             CTD
Vetere, Fabián          SIHN            CTD

EL AUSTRAL 01-92 
Name                    Institution     Specialty
------------------------------------------------------------
Bianchi, Alejandro      SIHN            Jefe Científico
Balestrini, Carlos      SIHN            Responsable CTD
Berón, Javier           ITBA            CTD
Charo, Marcela          SIHN            Responsable CTD
López, Fernando         INIDEP          CTD/Nutrientes
Molina, Daniel          SIHN            Oxígeno disuelto
Moretti, Ana            ITBA            CTD
Negri, Rubén            INIDEP          Fitoplancton
Osiroff, Ana            SIHN/CONICET    Salinidad
Tosonotto, Gabriela     IAA             CTD


CONICET: Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos 
         Aires.
IAA:     Instituto Antártico Argentino, Buenos Aires.
INIDEP:  Instituto Nacional de Investigación y Desarrollo Pesquero, Mar del 
         Plata. 
SIHN:    Servicio de Hidrografía Naval, Buenos Aires.


REFRENCES

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FIGURE LEGENDS (all figures are available in the PDF version)

Figure 1.  Posición de las estaciones oceanográficas realizadas en la Campaña 
          Cap. Oca Balda 04-91.

Figure 2.  Posición de la estaciones oceanográficas y lanzamientos XBT 
          realizadas en la Campaña Dr. Eduardo L. Holmberg 04-92.

Figure 3.  Posición de la estaciones oceanográficas realizadas en la Campaña El 
          Austral 0192


