WHP CRUISE SUMMARY INFORMATION

WOCE section designation
A16C

Expedition designation (EXPOCODE)
318HYDROS4

Chief Scientist(s) and their affiliation
Lynne Talley, SIO

Dates
1989.03.13 - 1989.04.19

Ship
MELVILLE

Ports of call
Montevideo, Uruguay to Bridgetown, Barbados

Number of stations
71

Geographic boundaries of the stations
	000.10''N
5200.90''W	2457.20''W
	3513.30''S

Floats and drifters deployed
none

Moorings deployed or recovered
none

Contributing Authors
none listed

WHP Ref. No.:	A16C
Last Updated:	June 16, 1992

Cruise Dates:	
March 13 - April 19, 1989 
Expedition:	
318MHYDROS/4 
Chief Scientist:	
Lynne Talley, SIO
Co-Chief Scientists:	
Mizuki Tsuchiya, SIO and James Orr, Princeton
Ship:	
R/V Melville
Ports of Call:	
Montevideo, Uruguay to Bridgetown, Barbados

1.	SUMMARY OF WORK

On March 13, 1989 the R/V Melville, under the command of Captain Robert 
Haines, left Montevideo, Uruguay, to undertake hydrographic work first in the 
territorial waters of Uruguay and then along longitude 25W from 32S to 
040'N, with a final short section across the equator at 3630'W.  The ship 
arrived in Bridgetown, Barbados on April 19, 1989, having completed the entire 
program with almost no difficulties.  Seventy-one CTD/rosette stations were 
occupied; at 7 sites, large-volume Gerard samples were also collected.  The 
first station number was 309, reflecting the integration of this cruise leg 
with the South Atlantic Ventilation Experiment (SAVE); Hydros 4 was the sixth 
and final leg of SAVE and was the fourth and final leg of the 25W section of 
McCartney, Talley and Tsuchiya.

Rosette and Gerard station positions are listed in the .SUM file.  For the 
most part, stations were spaced every 35 nautical miles (nm), with the 
exception of closer station spacing at the western boundary and 20nm spacing 
across the equator.  Table 1 lists all properties which were determined from 
discrete samples collected at each station.

Table 1: Parameters measured on Hydros leg 4 (A16C)

PARAMETER		PRINCIPAL INVESTIGATOR	INSTITUTION
CTD/O2 and Salinity 	J. Swift		SIO
Oxygen and Nutrients		
CFCs			R. Weiss and W. Smethie	SIO and LDGO
Helium/tritium		W. Jenkins		WHOI
Kr-85 (LVS) or Ar-39	R. Key			Princeton
C-14 (LVS)		
Ra-228 (surface)		
Ra-226 and Ra-228	J. Orr			Princeton
CO2			T. Takahashi		LDGO
Air chemistry		R. Weiss		SIO
XBTs		

In addition to standard and large-volume hydrographic stations, T-7 XBT's were 
dropped at 20nm intervals along the cruise track between stations 313 and 314; 
surface samples were collected at most locations.  Other than along this 
portion of the cruise track, 1 XBT was dropped each day for regular reporting, 
as described below.  XBT and underway sampling stations are listed in Table 2 
(not shown).

The scientists in charge of CTD/rosette sampling were L. Talley and M. 
Tsuchiya; J. Orr was responsible for the large volume component.

A.	CTD/Rosette Sampling

The CTD work and basic water sampling were carried out by Scripps Institution 
of Oceanography's Shipboard Technical Support/Oceanographic Data Facility 
(STS/ODF) with help from other members of the science party.  D. Muus and J. 
Boaz were team leaders for the two twelve-hour watches.  Rosette handling was 
optimal with four people on deck and one at the CTD console.  Rosette water 
sampling team sizes varied depending on the number of properties being 
samples; the minimum size was 2 (oxygen, salinity and nutrients) and the 
maximum size was 6 (adding CFC's, helium, tritium, and CO2).

Sampling at each station included a CTD/O2 cast with a rosette carrying 36 
ten- liter bottles.  A single Neil Brown Mark-3 CTD was used throughout the 
cruise. Also mounted on the rosette frame and connected to the CTD were a 
transmissometer and a Benthos altimeter.  A Benthos pinger with a self-
contained battery pack was mounted separately on the rosette frame; its signal 
was displayed on the precision depth recorder (PDR) in the ship's laboratory.  
The rosette/CTD was suspended from a three- conductor wire which provided 
power to the CTD and relayed the CTD signal to the laboratory. 

Each CTD cast extended to within 10m of the bottom unless the bottom returns 
from both the pinger and the altimeter were extremely poor.  All 36 bottles 
were used on stations exceeding 3500m depth.  Water samples were collected 
from the ten-liter bottles for salinity, oxygen, nutrients (silicate, 
phosphate, nitrate and nitrite), chlorofluorocarbons (CFC-11 and CFC-12), 
total and partial CO2, helium-3, and tritium.  All but the helium and tritium 
analyses were done at sea.

CTD data was relayed at 25 Hz, acquired with an ODF deck unit, and partially 
processed in real time on ODF's Integrated Solutions, Inc. (ISI) computers.  
Analog data was recorded simultaneously on VCR tapes as a backup.  Real-time 
processing included 0.5 second block-averaging with a filter to remove bad 
samples; preliminary corrections were applied in real time to the data which 
were then continuously updated on up to 4 plots displayed on the computer 
monitor.  Immediately after each station, the data were pressure-sequenced and 
desired plots were produced.  During the course of the cruise, M. Johnson of 
ODF continued the calibration procedures using discrete salinity and oxygen 
samples collected from the rosette.  The CTD temperature calibration was 
monitored with one rack of reversing thermometers mounted on the second bottle 
from the bottom; at station 367 a second rack near the bottom was added in 
order to monitor a drift in temperature difference between the thermometers 
and the CTD.

Salinity samples were analyzed on two Guildline Autosals by F. Mansir and C. 
Hallman; oxygen samples were titrated by D. Muus, A. Hester, and M. Tsuchiya; 
nutrient analyses on a modified Technicon autoanalyzer were performed by D. 
Masten.  L. Cartwright reread all of the nutrient charts as part of the usual 
ODF quality control.  D. Muus processed the discrete salinity, oxygen, and 
nutrient measurements.  During the cruise, summaries and plots of all data 
were available for quality control and interpretation within a day of 
collection.  D. Muus and M. Tsuchiya carefully checked all of the data as it 
became available.  Vertical sections of all parameters were available 
throughout the cruise.  All ODF data were available on the ISI computers for 
further dynamic computations and mapping throughout the cruise.

The total station time (actual CTD time plus extra time when the Melville was 
stopped on station during which the CTD was not in the water) on each station 
was commonly 2 to 4 hours depending on the water depth.  The extra time was 
generally 0.3 to 0.4 hours per station, even in excellent weather which we 
enjoyed throughout the cruise, because of the relative difficulty of handling 
the large double rosette package with an 800 lb. weight.

CFC samples were collected at a subset of the stations and were analyzed at 
sea on two separate systems, for Ray Weiss of SIO and Bill Smethie of Lamont-
Doherty Geological Observatory (LDGO).  P. Salameh and M. Trunnell operated 
the SIO system and J. Raznewski the LDGO system.  After some initial cross-
checking of methods on the two systems, results produced by the two systems on 
duplicate samples were in good agreement.  Plots of all data were available at 
sea; vertical sections were produced at the conclusion of the cruise using an 
interface to the ODF system.  

Throughout the cruise, air and surface water samples were analyzed every half 
hour for CH4, N2O, and CO2 by P. Salameh for Ray Weiss.

Partial and total CO2 measurements were made at a subset of the stations for 
Taro Takahashi (LDGO) by M. Noonan and K. Bosley.  Station data plotting was 
available on the Melville's VAX 730; vertical sections were plotted on the ODF 
system.  At approximately every fourth station, duplicate samples at a pair of 
surface bottles (4 m) were collected for comparison of the at-sea LDGO 
measurements with later analysis by C. Keeling at SIO.  Four standards 
prepared in Keeling's laboratory were run during the cruise.  At two stations, 
15 samples were collected and analyzed for alkalinity.  At three stations, air 
samples were collected for later pCO2 analysis at LDGO.

Samples for later analysis of helium-3 and low-level tritium were collected at 
approximately every fourth station by S. Doney for the Jenkins group at Woods 
Hole Oceanography Institution (WHOI).

Surface samples for radium analysis were collected near the location of every 
CTD/rosette station and at approximately 2 longitude intervals along the 
steam from the last station to Barbados by J. Orr.

Vertical sections of all properties, gridded using Roemmich's (1983) method 
and contoured using NCAR graphics, are included in this report.

B.	Gerard Sampling

As with SAVE Legs 1-5, large volume samples were collected by Gerard barrel 
(250-liter) hydrocasts. These samples were often processed sequentially for 
Krypton- 85 (or Argon-39), Carbon-14, and Radium-228.  However, for many 
samples, this complete suite of analyses was not performed because of the 
different region of interest for each species within water column.  Also, each 
species must be processed and the extract sent to its shore-based analytical 
facility; different samples quotas are mandated by the different facilities.

Ancillary measurements (on small volumes) for each Gerard cast included 
salinity (both on Gerards and their attached 5-liter Niskins), temperature 
(from the reversing thermometer on the 5-liter Niskin), total CO2 (on each 
Gerard where C-14 was analyzed), and chlorofluorocarbons (from the five-liter 
Niskin only for all samples of Kr and from the top and bottom samples of the 6 
Gerards tripped for one Ar sample).  Unfortunately, no Barium samples were 
collected from the attached five-liter Niskins because analytical supplies 
were exhausted during the previous SAVE Leg 5.

Typically, two 9-barrel Gerard casts were taken per station and were separated 
by one rosette cast.  Four people were required on deck for the Gerard barrel 
handling.  Upon arrival on station, first in the water was the deep Gerard 
cast.  For the deep cast, any depths specifically targeted for sampling were 
selected using the CTD/O2 profile from the immediately preceding station 
(usually within 35nm).  Subsequent to the deep Gerard cast, the rosette was 
deployed and results from its CTD/O2 trace were used similarly to target 
depths for the subsequent shallow Gerard cast.  Selection criteria included 
samples from the surface mixed layer, in and around the thermocline at 
predetermined sigma-theta surfaces (25.6, 26.2, 26.5, 26.8, 27.1, and 27.4), 
the salinity minimum associated with the Antarctic Intermediate Water (AAIW), 
the salinity maximum- oxygen maximum associated with the North Atlantic Deep 
Water (NADW) (1700-3000m), sigma-2 = 36.85, and sigma-4 = 46.85.  Near bottom 
samples were collected at approximately 20, 150, and 500m above the bottom.  
Remaining Gerard barrels were used to "fill-in" gaps, leaving spaces no larger 
than 400m between samples; some stations required up to 500m spacing to 
adequately cover the water column.

In total, seven large volume stations were taken.  The first two stations were 
taken while steaming off the Uruguayan slope en route to longitude 25W.  At 
the first, station 310 in 1091m of water, one cast of 9 Gerard barrels 
adequately covered the water column.  The second station, station 313 (3066m), 
consisted of 3 casts because the more typical 9-barrel surface cast was split 
into 2 casts of 5 and 4 barrels.  This split was initiated to facilitate more 
processing time for the new Kr-Ar analyst while simultaneously eliminating 
idle wire time while sitting on this station.

Subsequent large volume sampling occurred only after steaming to 25W where 
the ship turned and headed due north.  Station 316 (previously referred to as 
LV1) and station 332 (LV2) were sampled in typical fashion employing shallow 
and deep casts.  Further north along 25W, station 340 was sampled again with 
2 Gerard casts; however, this special station was planned to augment the 
limited sampling (shallower) feasible during SAVE Leg 2 at the same position; 
on that leg, only two Gerards were available per cast.  Thus station 340, 
previously referred to as SR1 (SAVE Repeat 1), was sampled with one deep 
Gerard cast and an additional cast collected near the bottom for Argon-39.  
Unlike all other stations, station 349 (LV3) necessitated 3 Gerard casts: (1) 
deep, (2) shallow, and (3) a cast specifically targeted at sampling Argon-39 
within the NADW.  Finally, station 376 (LV4) was also sampled with the usual 
2-cast sampling strategy, however, its original position at the equator along 
25W was shifted to 3630'W.  This shift allowed for sampling of the Antarctic 
Bottom Water (AABW) by moving from relatively shallow waters overlying the 
Mid-Atlantic Ridge (between the Romanche and St. Paul Fracture Zones) to the 
deeper water column above the Ceara Abyssal Plain.  The bottom water at 25W 
lies at a depth of approximately 3200dbar and 2.5C, while that at the altered 
position exhibits the presence of AABW with 0.5C water at its 4500dbar 
bottom.

During Hydros 4, 3 samples were collected for Ar-39 (6 Gerards/sample), 32 
samples for Kr-85, 108 for C-14, and 194 for Ra-228 (85 of these were taken 
from surface soaks, i.e., not via Gerard sampling).

C.	XBT and Underway Sampling

Except during the initial Uruguayan section, at least one XBT was dropped 
every afternoon for reporting to the National Oceanic and Atmospheric 
Administration (NOAA).  During the transit from station 313 to 314, an XBT was 
dropped every 2 hours, for a total of 78 stations at approximately 20nm 
spacing.  In all cases, T-7 probes were used, extending to a nominal depth of 
760m.  Data were acquired by an MK-9 system on the Melville's VAX 730 
computer.  Plots, isotherm depths, and inflection points were available 
immediately after each drop.  Inflection point data were relayed from the VAX 
730 to NOAA each day.  M. Moore of STS also produced a separate file of 
isotherm depths for the closely spaced section; these were transferred to 
ODF's system where vertical sections were produced by M. Johnson.

At XBT stations 33 to 74, surface samples were drawn and analyzed for 
salinity, total CO2 and partial CO2.

D.	Bottom Depth

An Edo Western precision depth recorder (PDR) was operated continuously during 
the cruise, except in Brazilian territorial waters surrounding St. Peter and 
Paul Rocks.  The PDR operation was overseen by J. Boaz.  An underway watch was 
maintained to log data every 5 minutes; data were entered on the VAX 730 and 
merged with navigation for later transfer to the Geological Data Center at 
SIO.  M. Moore also produced Carter-corrected depths for use in plotting the 
vertical sections.  The PDR functioned well in shallow depths and regions of 
sedimentation.  However, along 25W, the bottom topography was highly 
irregular and probably rocky; the trace was generally very difficult to 
follow, despite repeated maintenance.

2.	PRELIMINARY RESULTS

During the cruise, vertical sections, vertical profiles, printed output and 
all files on the ODF computers permitted a preliminary look at the data and 
its implications.  In addition, dynamic heights and geostrophic velocities 
were computed; isopycnal maps of various properties were constructed using all 
of the SAVE data and several other cruises which had been included in the 
computer data files.  Because it is impossible in this space to describe all 
of the data or to anticipate all of the uses to which it will be put, only a 
few selected items are discussed, highlighting what we think are some major 
new features exposed by the Hydro 4 transect of the Brazil Basin.  Isopycnal 
maps of salinity (at 27.1 sigma-theta) and oxygen (at 37.02 sigma-theta) 
constructed from the SAVE, Hydros, AJAX, and 11S stations illustrate some of 
these points.

A.	Brazil Current (Hydros 4 stations 309-313 and Hydros 3 stations 305-308).

The surface expression of the Brazil Current (upper 1000dbar) is confined to 
stations 309 to 312, that is, within 60km of the 200m isobath.  (The strong 
southward current in this region resulted in an arced station "line").  In the 
upper 1000m immediately offshore of the Brazil Current was a cold/fresh 
"eddy"; offshore of the cold feature is another warm/saline feature.  Thus the 
circulation in the upper 1000m reflects the meandering and intermingling of 
the Brazil and Malvinas Currents.

The low salinity AAIW, at about 800dbar, is cleary split by the strong 
offshore northward flow: since the AAIW in both the Brazil Current and the 
offshore cold eddy is much saltier than the AAIW at station 305 and east, it 
appears that the AAIW in the cold eddy originated in the Brazil Current rather 
than farther to the south.

Between 1000 and 2000m lies the Upper Circumpolar Water, evidenced by a strong 
oxygen minimum and NO3/PO4/SiO3 maxima.  It is best "developed", with greatest 
extrema, offshore.  It is separated vertically from the Lower Circumpolar 
Water (LCW) by the unmistakable NADW.  The LCW, centered at 3520dbar, is also 
an oxygen minimum and is also best developed offshore.

The NADW, between 2000 and 3000dbar, is an obvious salinity and oxygen 
maximum.  The extrema are highest right at the continental rise, indicating 
southward flow there.

Just above the bottom, where potential temperature is negative, is a slight 
but significant salinity minimum, which is also an oxygen maximum.  Displaced 
slightly inshore (at stations 306-308) is a high silicate and nitrate feature, 
right at the bottom.  Its source (direction of flow) is not clear at present, 
although it is of Antarctic origin.

Geostrophic velocities were computed for the section.  An initial reference 
level at the bottom was used.  The initial velocities were compared with the 
water mass features from which the direction of flow could be deducted.  With 
a reference level at the bottom (deepest common level for a station pair), the 
velocity profiles matched the deduced water mass flow directions quite nicely.  
The only questionable flow feature is the direction of the bottom water: 
placement of a level of no motion at the 0C isotherm was also tried; this 
produced weak northward bottom flow with almost no change in velocities 
through the rest of the column and little change in transport.

Preliminary isopycnal maps, constructed from all SAVE data, at 27.1 sigma-
theta (AAIW), 36.95 sigma-2 (Middle NADW), 37.02 sigma-2 (O2 minimum), 45.88 
sigma-4 (Lower NADW), 46 0 sigma-4 (transition), 46.02 sigma-4 (AABW), and 
46.08 sigma-4 (Argentine Basin bottom), confirm that the flow directions 
acquired from a bottom reference level of no motion are qualitatively correct.  
The map at 46.08 sigma-4 shows no convincing direction of flow; hence the 
statement in the previous paragraph that the flow direction in this layer is 
as yet unknown.

Transports were calculated across the short section.  Maximum northward 
transport was 23Sverdrups between stations 313 and 308; maximum southward 
transport was 37Sverdrups between stations 307 and 306.  Integrated from the 
coast to offshore, the maximum southward transport was 45Sverdrups.  Since it 
is difficult to determine exactly what should constitute the Brazil Current, 
two definitions are used:

(1)	between stations 309 and 312, covering the most intense coastal 
southward flow, yielding a total of 11Sverdrups to the bottom, and

(2)	maximum southward transport integrated offshore, yielding 45Sverdrups 
relative to the bottom or 42Sverdrups relative to the 0C isotherm.  The 
maximum southward-integrated transport occurs at station 306.  This definition 
of the Brazil Current therefore includes the southward-flowing NADW and the 
strong southward surface flow east of the cold intrusion.  The northward flow 
between stations 312 and 308 is included in this total since it is presumed 
that in this extremely variable region, a large portion of the northward flow 
is merely returned to the south.

B.	Equatorial Region

Of primary consideration here is the section at 25W.  Very obvious in the 
water mass structure in the equatorial region are: the thermostat of the 13C 
water, which extends to 5S, and 8.5C "water mass" centered at the equator, 
the AAIW, the Upper, Middle and Lower NADW, an oxygen minimum separating the 
MNADW and LNADW, and the AABW.

The 13 water is remarkably well defined on CTD casts, with very abrupt 
transitions above and below the nearly uniform layer.  The "8.5 water" is 
also fairly well defined and centered at the equator.  Both of these water 
masses may be more a consequence of the local dynamics rather than an 
indication of a particular formation process.  On the other hand, double 
diffusion may be of some importance in this region in the thermocline, as 
evidenced by frequent observations of stair- steps at the tropical stations.

An obvious natural feature which affects the equatorial flow at 25W is the 
mid-Atlantic Ridge, which rises from the abyssal plain (about 4500m deep) to 
3200m at the equator.  The rise occurs at about 130'S, well within the range 
of equatorial flow.  Since the ridge continues irregularly to the north at 
this longitude, equatorial flow is forced around the ridge to the south.  The 
most dramatic effect in the vertical sections is the displacement of the high-
oxygen core of the Lower North Atlantic Deep Water (LNADW) to the south where 
it hugs the ridge.  It is most strongly developed between 1.7S and 4S.  The 
cores of low nutrients associated with the high-oxygen core also show 
southward displacements from the equator.  The effect of the bottom topography 
also extends to AAIW at much shallower depths, well above the ridge depth.  
The oxygen and nutrient sections show weakly developed cores of high 
concentration slightly south of the equator.  Oxygen and salinity maps at 27.1 
sigma-theta show that AAIW flows up the western boundary and spreads eastward 
at the equator.  At 25W, the core is displaced to the south by the 
topography.

The UNADW is marked by a salinity and CFC maximum.  The most extreme values of 
each are clearly located south and north of the equator, as if the eastward 
equatorial flow splits around the topographic barrier.  The August, 1988, 
section at 25W which extended across the equator to 3S also showed the cores 
displaced somewhat to the south, although at that time salinity higher than 
34.98psu was found at the equator, with no separate core north of the equator.

The MNADW, marked by an oxygen maximum and nutrient minima at about 2000dbar 
(saturation maximum at 1800dbar), is clearly displaced south of the equator at 
25W.

Another effect of the ridge is to produce a well-mixed layer at the bottom 
centered at the equator.  The layer is about 300m thick and is composed of 
water from shallower depths, being therefore anomalously warm, saline, light, 
and oxygenated relative to waters to the north and south at the same depth.  
This mixed layer is most evident in the CTD oxygen profiles.

The oxygen minimum separating the MNADW and LNADW is well developed only south 
of the equator.  Two factors may be relevant, based on isopycnal maps: (1) 
eastward flow at this level, carrying high O2 is directly at the equator and 
continuous with a core farther west, and (2) the water column is well-mixed at 
the bottom at the equator, as remarked above, specifically in the part of the 
column usually occupied by the oxygen minimum.

Finally, an equatorial geostrophic calculation has not yet been made, but the 
vertical sections of potential density suggest that there might be at least 
five identifiable layers in the equatorial region (within 4 of the equator).  
Two additional layers are found south of the ridge, within the equatorial zone 
(the LNADW and the Antarctic Bottom Water, which have strong density 
signatures).

C.	North Atlantic Deep Water (NADW)

The well known split of NADW into Upper (salinity maximum), Middle (upper 
oxygen maximum), and Lower (lower oxygen maximum) was recognized and named by 
Wust (1935).  This split is well defined on the short 3630'W-equatorial 
section and on the 25W section from the mid-Atlantic ridge (1.7S) to about 
16S.  The oxygen minimum that separates the MNADW and the LNADW is associated 
with a slight minimum or weak vertical gradient of salinity and with clearly 
defined maxima of SiO3, PO4, and NO3.  Salinity and oxygen decrease nearly 
monotonically at all depths in the NADW from the equator southward to 16S.  
In what is perhaps the most memorable feature of the new 25W data, a strong 
NADW core reappears at about 18S, with highest salinity, oxygen and 
chlorofluorocarbons in a plug between 18 and 25S.  Sections of nutrients also 
show a core of low concentration in the NADW in these latitudes.  The NADW in 
this region is not clearly differentiated into its three "parts", although the 
highest salinity is located slightly above the oxygen maximum.  It is 
hypothesized that this strong core is flowing eastward, with its source at the 
western boundary.  This is totally supported by isopycnal maps at intersecting 
densities, which show a tongue of high oxygen extending southward, from the 
North Atlantic, along the western boundary to this latitude and then 
stretching eastward across the Brazil Basin.

Of the isopycnals considered (listed above), the strongest signature of this 
boundary current and eastward flow is at 37.02 sigma-2, which is actually the 
density of the oxygen minimum splitting the MNADW and LNADW.  The isopycnal 
maps show that the low oxygen north of 16S originates in the southeastern 
South Atlantic and is brought northward and westward in broad anticyclonic 
flow; the high oxygen tongue centered at 22S is the eastward limb of that 
flow.

A final remarkable feature of the 25W section is the extremely sharp 
transition between the LNADW and AABW in the equatorial region.  This 
undoubtedly results from the proximity to the North Atlantic and the nearly 
unaltered character of the LNADW.

D.	Dynamic Heights and Circulation

Dynamic heights were computed at sea from the CTD data; because the quality of 
the CTD data is extremely high and because the calibration of the particular 
CTD used was quite stable throughout the cruise, the final, calibrated results 
will be similar.  Dynamic heights and geostrophic velocities were calculated 
for all stations along 25W, including those from Hydros 3 (SAVE 5) between 
32S and 54S.

Dynamic height at all levels in the upper 1000dbar relative to any deeper 
reference level is maximum at 28S; this then is the center of the subtropical 
gyre.  As is known and is the case in all other ocean basins, the most 
dramatic fronts, with largest changes in dynamic height, occurs pole-ward of 
the subtropical gyre center, and are in the eastward flow.  The identifiable 
thermal fronts on this section Hydros 3 along 25W are: the subtropical front 
at 28-30S, the Brazil Current at 42S, the Subantarctic Front at 45-47S, and 
the Antarctic Polar Front at 49-51S.  Even though the strongest fronts occur 
in the eastward flow, a regular but gentler undulation surface dynamic heights 
also occurs north of 28S.  The dominant length scale of undulations/frontal 
spacing from 54S to the equator is about 4of latitude (400km) and appears to 
be independent of latitude.  (A similar phenomenon has been observed on a 
well-resolved meridional section in the eastern North Pacific.)

Because of the undulation in dynamic topography, geostrophic velocities are 
noisy, reversing constantly along the section.  However, the dynamic 
topography indicates that the predominant large-scale flow north of 28S is 
westward, all the way to the equator.

Further work with the velocities has not yet been completed, as this report is 
being written at the conclusion of the cruise.  Because of the noise in the 
station-to-station velocities, it has not yet been possible to match them with 
the large-scale intermediate and deep circulations as deduced from the 
isopycnal maps; in particular the apparent eastward flow of NADW between 19 
and 25S has not emerged.  Further work will be forthcoming and results 
presented in published form.

3.	BOTTLE DATA COLLECTION, ANALYSES, AND PROCESSING

ODF CTD/rosette casts were carried out with a 36-bottle rosette sampler of ODF 
manufacture using a General Oceanics pylon.  An ODF-modified NBIS Mark 3 CTD, 
a Benthos altimeter and a SeaTech transmissometer provided by Texas A&M 
University (TAMU) were mounted on the rosette frame.  Seawater samples were 
collected in 10-liter PVC Niskin bottles mounted on the rosette frame.  A 
Benthds pinger with a self-contained battery pack was mounted separately on 
the rosette frame; its signal was displayed on the precision depth recorder 
(PDR) in the ship's laboratory.  The rosette/CTD was suspended from a three-
conductor wire which provided power to the CTD and relayed the CTD signal to 
the laboratory.

Each CTD cast extended to within 10 meters of the bottom unless the bottom 
returns from both the pinger and the altimeter were extremely poor.  The 
bottles were numbered 1 through 36.  If one of these 36 bottles needed 
servicing and repairs could not be accomplished by the next cast, the 
replacement bottle was numbered 71-78.  Added CTD levels, no water samples, 
were assigned bottle numbers 95-99.  Subsets of CTD data taken at the time of 
water sample collection (a 10 second average) were transmitted to the bottle 
data files immediately after each cast to provide pressure and temperature at 
the sampling depth, and to facilitate the examination and quality control of 
the bottle data as the laboratory analyses were completed.

After each rosette cast was brought on board, water samples were drawn the 
following order: Freon (CFC-11 and CFC-12), Helium-3, Oxygen, Oxygen-18, pCO2, 
TCO2, Tritium, Nutrients (silicate, phosphate, nitrate and nitrite), Salinity 
and Suspended Particulate Matter.  Table 3 is a tabulation of samples 
collected during all six legs (SAVE Legs 1 through 5 (STS/ODF, 1992) and 
HYDROS Leg 4 (STS/ODF, 1992)] unless otherwise noted and includes the 
Principal Investigators and their institutions.  Other ancillary program 
samples were drawn after the core samples.  The samples and the Niskin sampler 
they were drawn from were recorded on the Sample Log sheet.  Comments 
regarding validity of the water sample (valve open, lanyard caught in lid, 
etc.) were also noted on the Sample Log sheets.

Gerard casts were carried out with approx.  270 liter stainless steel Gerard 
barrels on which were mounted 2-liter Niskin bottles with reversing 
thermometers.  Samples for Salinity, 14C, 228Ra, 39Ar, and 85K were obtained 
from the Gerard barrels.  The Gerard barrels were numbered 81 through 91 and 
the piggy-back Niskin were numbered 41 through 70.  Surface samples taken from 
the ship's underway pump line were assigned a bottle number of 98 through 99.  
Salinity check samples were always drawn from the Niskin bottles for 
comparison with the Gerard barrel salinities to verify the integrity of the 
Gerard sample.  Occasionally, barium and some of the samples normally taken 
from the rosette were also drawn from the Gerard-mounted Niskin bottle.  These 
were also recorded on a Sample Log sheet.

The discrete hydrographic data were entered into the shipboard data system and 
processed as the analyses were completed.  The bottle data were brought to a 
useable, though perhaps not final, state at sea.  ODF data checking procedures 
included verification that the sample was assigned to the correct level.  This 
was accomplished by checking the raw data sheets, which included the raw data 
value and the water sample bottle, versus the sample log sheets.  Any comments 
regarding the water samples were investigated.  The raw data computer files 
were also checked for entry errors.  Investigation of data included comparison 
of bottle salinity and oxygen with CTD data, and review of data plots of the 
station profile alone and compared to nearby stations.

If a data value did not either agree satisfactorily with the CTD or with other 
nearby data, then analyst and sampling notes, plots, and nearby data were 
reviewed.  If any problem was indicated the data value was flagged or deleted.  
(However, ODF preserves in its archives all bottle data values).  Appendix B, 
the Bottle Data Processing Notes, includes comments regarding deletion of 
samples.

If it was determined that an entire 10 liter water sample was contaminated by 
leakage or other bottle or rosette malfunction, the level was reported with 
just the CTD data (pressure, temperature and salinity).  This has been done to 
preserve the profile and accommodate investigators who prefer using bottle 
data files exclusively.

A.	Pressure and Temperatures

All pressures and temperatures for the Niskin bottle data tabulations on the 
rosette casts were extracted from the processed CTD data, usually those from 
the corrected 10-second average bottle trip files collected during the up cast 
(see CTD DATA COLLECTION, ANALYSES, AND PROCESSING).

Gerard pressures and temperatures were calculated from Deep-Sea Reversing 
Thermometer (DSRT) readings.  Each DSRT rack normally held 2 protected 
(temperature) thermometers and 1 unprotected (pressure) thermometer.  
Thermometers were read by two people, each attempting to read a precision 
equal to one tenth of the thermometer etching interval.  Thus, a thermometer 
etched at 0.05 degree intervals would be read to the nearest 0.005 degree.  
Each temperature value is therefore calculated from the average of four 
readings.  IT SHOULD BE CLEARLY NOTED THAT THE TEMPERATURES PRODUCED AND 
PUBLISHED BY ODF IN THIS REPORT ARE BASED ON THE INTERNATIONAL PRACTICAL 
TEMPERATURE SCALE OF 1968, RATHER THAN THE CURRENTLY USED INTERNATIONAL 
TEMPERATURE SCALE OF 1990.  (The expedition took place before 1 January 1990, 
the starting date for ITS-90).

B.	Salinity

Salinity samples were drawn into ODF citrate salinity bottles which were 
rinsed three times before filling.  Salinity was determined after sample 
equilibration to laboratory temperature, usually within about 8-36 hours of 
collection.  Salinity has been calculated according to the equations of the 
Practical Salinity Scale of 1978 (UNESCO, 1981) from the conductivity ratio 
determined from bottle samples analyzed (minimum of two recorded analyses per 
sample bottle after flushing) with a Guildline Autosal Model 8400A salinometer 
standardized against Wormley P-108 standard seawater, with at least one fresh 
vial opened per cast, or from the corrected CTD conductivity, temperature, and 
pressure.

Accuracy estimates of bottle salinities run at sea are usually better than 
0.002 psu relative to the specified batch of standard.  Although laboratory 
precision of the Autosal can be as small as 0.0002 psu when running replicate 
samples under ideal conditions, at sea the expected precision is about 0.001 
psu under normal conditions, with a stable lab temperature.  Still, because a 
small droplet of fresh water, or the residue from a small evaporated droplet 
of seawater, can affect a bottle salinity in the third decimal place, and 
because the Autosal salinometer is sensitive to environmental fluctuations, 
salinities from bottle samples have a lower true precision under field 
conditions than in the laboratory.  ODF typically deleted the Niskin bottle 
salinity from this report and substituted the corrected CTD salinity whenever 
there was any question regarding its validity (see BOTTLE DATA PROCESSING 
NOTES).

C.	Oxygen

Samples were collected for dissolved oxygen analyses soon after the rosette 
sampler was brought on board and after CFC and Helium were drawn.  Nominal 100 
ml volume iodine flasks were rinsed carefully with minimal agitation, then 
filled via a drawing tube, and allowed to overflow for at least 2 flask 
volumes.  Reagents were added to fix the oxygen before stoppering.  The flasks 
were shaken twice; immediately, and after 20 minutes, to assure thorough 
dispersion of the Mn(OH)2 precipitate.  The samples were analyzed within 4-36 
hours.  Dissolved oxygen samples were titrated in the volume-calibrated iodine 
flasks with a 1 ml microburet using the whole-bottle Winkler titration 
following the technique of Carpenter (1965).  Standardizations were performed 
with 0.01N potassium iodate solutions prepared from pre-weighed potassium 
iodate crystals.  Standards were run at beginning of each session of analyses, 
which typically included from 1 to 3 stations.  Several standards were made up 
and compared to assure that fine results were reproducible, and to preclude 
basing the entire cruise on one standard with the possibility of a weighing 
error.  A correction (- 0.014 ml/l) was made for the amount of added with the 
reagents.  Combined reagent/seawater blanks were determined to account for 
oxidizing, or reducing in the reagents and for a nominal level of natural 
iodate (Brewer and Wong, 1974) or other oxidizers/reducers in fine seawater.

The quality of the KIO3 is the ultimate limitation on fine accuracy of this 
methodology.  The assay of the finest quality KIO3 available to ODF is 100%,  
0.05%.  The true limit in the quality of the bottle oxygen data probably lies 
in the practical limitations of the present sampling and analytical 
methodology, from the time the rosette bottle is closed through the 
calculation of oxygen concentration from titration data.  Overall precision 
within a group of samples has been determined from replicates on numerous 
occasions, and for the system as employed on this expedition one may expect 
0.1 to 0.2%.  The overall accuracy of the data is estimated to be 0.5%.

D	Nutrients

Nutrients (phosphate, silicate, nitrate and nitrite) analyses, reported in 
micromoles/liter, were performed on a Technicon AutoAnalyzer.  The procedures 
used are described in Hager et al.  (1972) and Atlas et al.  (1971).  
Standardizations were performed with solutions prepared aboard ship from pre-
weighed standards; these solutions were used as working standards before and 
after each cast (approximately 36 samples) to correct for instrumental drift 
during analyses.  Sets of 4-6 different concentrations of shipboard standards 
were analyzed periodically to determine the linearity of colorimeter response 
and the resulting correction factors.  Phosphate was analyzed using hydrazine 
reduction of phosphomolybdic acid as described by Bernhardt & Wilhelms (1967).  
Silicate was analyzed using stannous chloride reduction of silicomolybdic 
acid.  Nitrite was analyzed using diazotization and coupling to form dye; 
nitrate was reduced by copperized cadmium and then analyzed as nitrite.  These 
three analyses use the methods of Armstrong et al. (1967).

Sampling for nutrients followed that for the tracer gases, CFC's, He, Tritium, 
and dissolved oxygen.  Samples were drawn into approx. 45 cc high density 
polyethylene, narrow mouth, screw-capped bottles which were rinsed twice 
before filling.  The samples may have been refrigerated at 2 to 6C for a 
maximum of 15 hours.

4	CTD DATA COLLECTION, ANALYSES, AND PROCESSING

Hydros-4 was processed with Year-2 of SAVE (Legs 4 and 5), therefore there may 
be references made to the SAVE Expedition.

71 CTD casts were completed using a 36-bottle rosette sampling system and 
STS/ODF CTD #1, a modified NBIS Mark III-B instrument.  The CTD data were 
initially processed into a filtered, half-second average time-series during 
the data acquisition.  The pressure and PRT temperature channels were 
corrected using laboratory calibrations.  The conductivity/salinity channels 
were calibrated to salinity check samples acquired on each cast.  The CTD 
time-series data were then pressure-sequenced into 2-decibar pressure 
intervals, and the pressure-series oxygen channel was corrected to match 
oxygen check samples acquired on each upcast.

A	CTD Laboratory Calibrations
A.1	Pressure Transducer Calibration

Each CTD pressure transducer was calibrated in a temperature-controlled bath 
by comparison with pressures generated by a Ruska Model 2400 piston gage.  The 
mechanical hysteresis loading and unloading curves were measured both pre- and 
post-cruise at cold temperature (-1 to 0.5C bath) to a maximum of 8830 psi, 
and at warm temperature (28-30C bath) to a maximum of 2030 psi.

B	PRT Temperature Calibration

The CTD-1 PRT temperature sensor was calibrated in a temperature-controlled 
bath by comparison with temperatures calculated from the resistance of a 
Rosemount Model 162CE standard platinum thermometer, measured by a NBIS model 
ATB 1250 resistance bridge.  The Rosemount standard PRT was checked 
periodically in water and diphenyl ether triple-point cells.  Seven or more 
calibration temperatures, spaced across the range of 0 to 30C, were measured 
both pre- and post-cruise.

5	ACKNOWLEDGEMENTS

Our thanks are extended to every member of the scientific and ship's crew for 
their hard work and dedication in producing this highest quality, excellently-
resolved data set.  From ship operations, deck-handling, winch operations, 
station-keeping, and water sampling to sample analysis and CTD calibration, 
every member of the party contributed their careful, thorough and efficient 
skills towards the fully successful results.  This data set was acquired under 
National Science Foundation, Ocean Sciences Division, through grants OCE 86-
14486 to Woods Hole Oceanographic Institution (McCartney, Talley and 
Tsuchiya), OCE 86-13330 to Lamont-Doherty Geological Observatory (South 
Atlantic Ventilation Experiment) and OCE 86-14378 to Scripps Institution of 
Oceanography (Oceanographic Data Facility).  The assistance provided by Dr.  
Neil Anderson and Dr.  Thomas Spence is gratefully acknowledged.

6	REFERENCES

Armstrong, F.A.J., C.R. Stearns, and J.D.H. Strickland, 1967. The measurement 
   of upwelling and subsequent biological processes by means of the Technicon 
   Autoanalyzer and associated equipment, Deep-Sea Research 14, 381-389.
Atlas, E.L., S.W. Hager, L.I. Gordon and P.K. Park, 1971. A Practical Manual 
   for Use of the Technicon AutoAnalyzer in Seawater Nutrient Analyses; 
   Revised. Technical Report 215, Reference 71-22. Oregon State University, 
   Department of Oceanography. 49 pp.
Bernhardt, H. and A. Wilhelms, 1967. The continuous determination of low level 
   iron, soluble phosphate and total phosphate with the AutoAnalyzer, 
   Technicon Symposia, Volume 1, 385-389.
Brewer, P.G. and G.T. E Wong, 1974. The determination and distribution of 
   iodate in South Atlantic waters. Journal of Marine Research, 32,1:25-36.
Bryden, H.L. 1973. New Polynomials for Thermal Expansion, Adiabatic 
   Temperature Gradient, Deep-Sea Research 20, 401-408.
Carpenter, J.H., 1965. The Chesapeake Bay Institute technique for the Winkler 
   dissolved oxygen method, Limnology and Oceanography 10, 141-143.
Carter, D.J.T., 1980 (Third Edition). Echo-Sounding Correction Tables, 
   Hydrographic Department, Ministry of Defence, Taunton Somerset.
Chen, C.-T. and E J. Millero, 1977. Speed of sound in seawater at high 
   pressures. Journal Acoustical Society of America, Volume 62, No. 5, 1129-
   1135.
Fofonoff, N.P., 1977. Computation of Potential Temperature of Seawater for an 
   Arbitrary Reference Pressure. Deep-Sea Research 24, 489-491.
Fofonoff, N.P. and R.C. Millard, 1983. Algorithms for Computation of 
   Fundamental Properties of Seawater. UNESCO Report No. 44, 15-24.
Hager, S.W., E.L. Atlas, L.D. Gordon, A.W. Mantyla, and P.K. Park, 1972. A 
   comparison at sea of manual and autoanalyzer analyses of phosphate, 
   nitrate, and silicate. Limnology and Oceanography 17, 931-937.
Lewis, E.L., 1980. The Practical Salinity Scale 1978 and Its Antecedents. IEEE 
   Journal of Oceanographic Engineering, OE-5, 3-8.
Mantyla, A.W., 1982-1983. Private correspondence.
Millero, E J., C.-T. Chen, A. Bradshaw and K. Schleicher, 1980. A New High 
   Pressure Equation of State for Seawater. Deep-Sea Research 27A, 255-264.
Roemmich, D.R., 1983. Optimal estimation of hydrographic station data and 
   derived fields. J. Phys. Oceanogr., 13, 1544-1549.
Saunders, P.M., 1981. Practical Conversion of Pressure to Depth. Journal of 
   Physical Oceanography 11,573-574.
Sverdrup, H.U., M.W. Johnson, and R.H. Fleming, 1942. The Oceans, Their 
   Physics, Chemistry and General Biology, Prentice-Hall, Inc., Englewood 
   Cliff, NJ.
STS/ODF, 1992. South Atlantic Ventilation Experiment (SAVE) Chemical, Physical 
   and CTD Data Report, Legs 1, 2 and 3. SIO Reference #92-9.
STS/ODF, 1992. South Atlantic Ventilation Experiment (SAVE) Chemical, Physical 
   and CTD Data Report, Legs 4 and 5. SIO Reference #92-10.
UNESCO, 1981. Background papers and supporting data on the Practical Salinity 
   Scale, 1978. UNESCO Technical Papers in Marine Science, No. 37, 144 p.

Table 3: SCIENTIFIC PROGRAMS

PARTICIPATING	PRINCIPAL			SCIENTIFIC
INSTITUTIONS	INVESTIGATORS			PROGRAMS
STS/ODF		Mr. David Wirth			Salinity, Oxygen, Nutrients
						-Nitrate, Nitrite,
						Phosphate, Silicate
						CTD Profiles
LDGO		Dr. Wallace S. Broecker		Carbon-14
MIAMI		Dr. H. Gote Ostlund	
MIAMI		Dr. Zafer Top	
WHOI		Dr. William J. Jenkins		Helium-3, Tritium
PRINCE		Dr. Jorge L. Sarmiento		Radium-228
PRINCE		Dr. Robert M. Key		Radium-226
SIO		Dr. Ray F. Weiss		Freon-11
LDGO		Dr. William M. Smethie, Jr.	Freon-12
LDGO		Dr. William M. Smethie, Jr.	Krypton-85
BERN		Dr. Heinz Loosli		Argon-39
LDGO		Dr. William M. Smethie, Jr.	
BERN		Dr. J.H. Oeschger	
LDGO		Dr. Taro Takahashi		Total CO2, pCO2
LDGO		Dr. Arnold Gordon		XBT Profiles
LDGO		Mr. Stanley Jacobs	
ANCILLARY PROGRAMS
TAMU		Dr. Wilford Gardner		Suspended Particulate Matter
						Transmissometer
SIO		Dr. Charles D. Keeling		Total CO2
SIO/GDC		Mr. Smart M. Smith		Bathymetry
LDGO		Dr. James K.B. Bishop		Barium
SIO		Dr. Ray E Weiss			Underway pN2O, pCO2, pCH4
------		-------				Underway Surface Measurements

INSTITUTION CODES:

BERN: Physics Institute of Bern, Switzerland
LDGO: Lamont-Doherty Geological Observatory of Columbia University
MIAMI: University of Miami
PRINCETON: Princeton University
SIO: Scripps Institution of Oceanography
SIO/GDC: Scripps Institution of Oceanography/Geological Data Center
STS/ODF: Shipboard Technical Support/Oceanographic Data Facility
TAMU: Texas A & M
WHOI: Woods Hole Oceanographic Institution

LIST OF PARTICIPANTS

Ship's Captain
	Robert Haines
	Scripps Institution of Oceanography

Chief Scientist
	Lynne D. Talley
	Scripps Institution of Oceanography

Co-chief Scientists
	Mizuki Tsuchiya
	Scripps Institution of Oceanography

	James C. Orr
	Princeton University

Lamont-Doherty Geological Observatory 
	Kathryn T. Bosley
	Maureen K. Noonan
	Jan Razniewski

Scripps Institution of Oceanography/ODF
	Craig M. Hallman
	Arthur W. Hester
	Mary Carol Johnson
	Forrest K. Mansir
	Douglas M. Masten
	David A. Muus

Scripps Institution of Oceanography
	Peter Salameh
	John T. Boaz
	Martha Denham
	Mike Moore
	Xiaojun Yuan

University of Washington 
	Matthew T. Trunnell

Woods Hole Oceanographic Institution
	Scott C. Doney

Naval Oceanographic and Hydrographic Service, Montevideo - Observer
	Lieutenant Ignacio Barreira-Carrau

Volunteer
	Larry Cartwright

-------------------------------------------------------------------------
318MHYDR4
A16c (HYDROS 4, pre-WOCE)
Talley/Tsuchiya

318MSAVE5
A16 (HYDROS3, SAVE5, pre-WOCE)
Smethie/McCartney

32OC202-1
A16 (MCTT - N. Atlantic, pre-WOCE)
McCartney/Talley/Tsuchiya

-----------------------
Data status: public.  CTD data do not seem to be available in WHP
format except for 32OC202-1, although they are all available at NODC
-----------------------
sum: no errors for all three
-----------------------
hyd: no need to sort since Gerard casts are not included
     no CFC's, tritium or helium included