NARRATIVE
The scientific party joined the vessel in the Pool of London alongside HMS
Belfast at 1430A 28-VI-90 (179). There was little in the way of equipment
preparation that could be done since most gear was to be loaded the following
day in Gt Yarmouth.
A photographer from the Guardian came to take pictures to accompany an article about the cruise (Guardian, 29-VI-90).
The vessel sailed at 1900A and made an uneventful passage overnight to Great
Yarmouth where she berthed at 0930A (29th,180)
Equipment from IOSDL was loaded, as were a number of items including the
moored ADCP and its mooring hardware from RVS. Two staff from Hydrographic
Dept Taunton were on hand to complete installation of the new automated XBT
recorder supplied by the Hydrographic Dept.
Equipment was installed in the labs and a base plate for the CTD unit modified
and bolted to the deck. Morag Stirling assembled and installed the fluorometer
for Cruise 51 and Steve Alderson helped to install the P STAR data processing
system. GPS position data were recorded throughout the port call in Gt
Yarmouth in order to try to assess the effects of the deliberate downgrading of
positional accuracy which had recently been imposed by the US Department of
Defense.
It was clear by mid afternoon that we would not be able to catch the afternoon
tide and sailing was therefore scheduled for 2300A.
A reporter from the Eastern Daily press who had seen the Guardian article
visited the vessel in the afternoon.
The vessel sailed at 2330A, after a delay due to pilots being busy. No
scientific watches were kept overnight but navigation data were logged.
June 30th (181) opened overcast with a falling barometer and with the vessel
making 12 kts northwards in a light sea. The scientific party continued
preparing equipment. Thermosalinograph logging was started and calibration
water samples from the non toxic seawater supply were taken at 4 hr intervals.
ADCP logging was started at mid morning.
The vessel passed through Pentland Firth between 1030-1100A (July 1,182) in
clear conditions but the weather worsened as we progressed northwestwards.
The vessel stopped at 1430A to deploy the PES fish and to test handling of the
new CTD and multisampler package. The unit was deployed without bottles and
with two 40 kg lead weights strapped to the bottom ring. The frame handled
well and showed that it could be deployed and recovered with the ship's guard
rails in place. The cantilever arm on the midships A frame seemed to steady
the package quite well.
Course was resumed towards 60 15N 06 00W but with speed reduced to 7-8 kts due
to weather.
At ca 1600A the ship stopped so that severe noise and vibration in area of
steering gear which had become apparent as the sea state had increased could be
investigated.. After considerable deliberation it was decided that there was a
serious problem, (probably with the rudder), and we set course at reduced revs
for Aberdeen.
The vessel arrived in Aberdeen by mid morning July 2nd (183). Divers
were on hand to inspect the rudder and propeller but nothing obvious was found.
The vessel remained in Aberdeen overnight for consultation with RVS. The
divers returned at 0800A (3rd) to inspect the bilge keels but again nothing
untoward was found. The vessel sailed at 1030A and conducted sea trials off
Aberdeen. The severe vibration and noise reappeared when the rudder was put
hard over at 12kts. RVS were informed and the vessel headed south towards
Leith which was the nearest available drydock. We were informed in the
afternoon that the Leith drydock was not available and that we should head for
the Tyne.
The Tyne pilot boarded at 1000A 3rd (184) and the vessel arrived in dry dock in
Wallsend at noon. The dock was pumped out by 1600 and tests on the rudder were
carried out. These identified slack in the lower pintle bush and work was
commenced to rectify the matter.
The vessel remained in dock throughout the 4th and 5th with the ship's
personnel remaining on board. Repairs to the rudder were almost completed by
evening of 6th. The vessel sailed at 1400A 7th (188) but took a long time to
clear dock as she became stuck across the dock entrance on the flooding tide.
We cleared the mouth of Tyne by 1545A and retried the same helm- hard- over
manoeuvres as before. The noise and vibration were still present.
The vessel returned to dry dock after Paul Stone (RVS Engineering
Superintendent) and the dock manager had joined the ship by pilot boat to
witness the problem at first hand.
Suspicion now fell on the skeg which attaches the propeller rope guard to the
shell plating. Some minor cracking and rust streaks had been noticed around
that area. The vessel returned to port and was alongside the drydock by
2330A.
The vessel entered drydock again at 1500A 8th (189) and when the dock had been
drained it was found that the rope guard could indeed vibrate and hit rudder.
Work was commenced to remove the guard and repair the cracks.
After telephone discussions on the morning of the 9th with Trevor Guymer
(Acting Head Marine Physics), Peter Saunders and Colin Summerhayes it was
agreed that a cruise extension would be impracticable due to fact that most of
officers were due to change at end of the present cruise.
Repair work continued throughout the night and the vessel sailed at 1630A
after a number of pinhole leaks in the skeg had been welded and the skeg
integrity tested. The breakwater was cleared by 1800A and course set
northwards. High speed manoeuvres produced some noise but the previous
problems appeared to have been largely solved. Passage continued northwards at
12.5 kts.
An Inmarsat message was received from Hendrik van Aken on R/V Tyro.
They had been delayed through bad weather and would not complete WOCE section
AR7 to Greenland.
Passage continued northwards throughout July 10th (191) in stiff northerly
winds. The vessel arrived in the Pentland Firth 1630A and encountered heavy
swell. This rapidly abated. At 1800A the PES fish was deployed. At 1820A an
ADCP calibration run at 10 kts was started on courses 000 and 270. This
continued until 2100A when the GPS satellite constellation reduced from 4 to
2.
The wind increased to F8 overnight 10th/11th with a heavy beam sea. Clocks
were retarded 1hr to GMT at midnight. The vessel arrived on station 0500Z/11th
(192) and after a wire test of two double acoustic release units, CTD CD50001
was worked to 1170m in centre of Faroe Shetland Channel. All 12 multisampler
bottles were fired at the bottom. All closed but two thermometer lanyards
caught up. (We later discovered that we were fixing the thermometer lanyards
in the wrong place).
The CTD package handled well despite the heavy sea and swell and 35kt winds.
We remained on station while the water sampling was completed. The CTD
conductivity sensor seemed very noisy and with a large offset and so it was
changed before the next station.
An attempt was made to get the XBT system working but there appeared to be
water in the launcher cable and in any case it was at that stage too dangerous
to go out on deck and launch probes.
Course was set towards the start of a section across the Iceland Basin but the
heavy seas prevented speeds in excess of 5 kts.
The wind abated overnight 11/12th but the heavy swell kept speeds to 8kts.
The vessel stopped at 1130Z to do wire tests of releases (2 dips) in the gap
between Bailey and Lousy Banks. These were completed by 1530 and course set
for start of CTD section.
The CTD section ( CD50002-020) was started at 1900Z. The CTD package proved
easy to handle with the new steadying roller on the A frame. On CD50007 the
PS2 data stream hung up on the down cast. The CTD was raised and lowered again
to cover the missing data.
The PSO talked to Tom Hopkins on R/V Alliance at 1645Z 13th (194).
Alliance had deployed two moorings on the Iceland Faroes Ridge. A
regular radio schedule was then established with Alliance at 1100Z each
day.
In working up the ADCP calibration run a fault was found with the gyro
interface box. It was found to miss a bit and put directions passing through
north as 180.
On 14th (195) the vessel stopped at 0030Z for wire tests of releases in 2200m
of water at the position of CD50012. Two lowerings were completed by 0530Z.
On station CD50014 the CTD connecting wire snagged under the shackle pin as
the CTD was being lifted from the deck and broke the conductor. While the
termination was being remade four more acoustic releases were tested to
1200m.
The section continued up the slope south of Iceland. Station CD50018 (in
about 1300m) was found to be downslope of a 50m deep channel. It was decided
to do CD50019 in the channel but no anomalously cold water was found. The
final CTD of the section, CD50020, in 700m was worked on the morning of 15th
(196).
During the day of the 15th moorings B,C,D,E and F were deployed along the CTD
line just occupied. (Details are in the mooring section and table.) Passage
between moorings was slow (7kts) due to fog. The fog cleared at 1330 leaving a
bright clear sunny day with southerly winds. Mooring deployment continued
through the day until 2200Z with the deployment of mooring F. This last
station was delayed somewhat by a hydraulic hose blowing out on the reeler of
the double barrelled mooring capstan. Overnight 15th/16th the first station
CD50021 of a line across the Iceland -Faroes Ridge was worked.
By 0500Z/16th the ship was in position to deploy mooring A. The vessel
remained at this position to record a longer series of ADCP data and mooring
deployment started at 0800Z. Mooring G, the last one was completed by 1100Z.
Course was then set for the next CTD of the line (CD50022). CTDs then
continued with XBT probes inbetween. The termination of the CTD wire failed at
CD50023 and had to be replaced before we proceeded. CTD stations continued
throughout 16th(197) and into 17th (198).
The surface expression of the Iceland-Faroes front was crossed ca 1500z 17th.
We encountered fog as we got towards the front.
The CTD section continued with adjustment of positions on the last two
stations to get a better distribution of depths.
On completion of the CTDs the vessel ran south to the position on the Iceland
Faroes ridge for the deployment of the ADCP mooring. The vessel arrived there
at 1530Z/18th (199) in thick fog. The sea surface temperature there was very
cold (5.5C). The mooring was deployed uneventfully by 1600Z. The vessel then
remained in position to see the acoustic releases time out and to await good
GPS coverage for fixing.
At 1700Z radio contact was made with Hopkins on Alliance and arranged a
rendezvous arranged for a CTD intercomparison on 64N. Prior to this a short
CTD section of 5 stations CD50038-042 was worked to look for water which might
have overtopped the ridge close to the ADCP mooring. The section was completed
by 2330Z/18th (199) and course set to rendezvous with Alliance.
We worked a station within 3 cables of Alliance (CTD50043)
0140-0200Z/19th(200) in 490m of water. Visibility was poor (0.5 miles) and
deteriorated further as we set course for the next CTD section. The fog
eventually cleared and the CTD section across the continental slope south of
Iceland was started at 0830Z/19th with XBTs between the first three stations.
The section continued through the day in good clear weather. Some problems
were encountered with the CTD deck unit hanging up when bottles were fired at
the bottom of the cast. The section was completed by midnight
A series of T7 XBT drops at half-hourly intervals was then started along the
700m depth contour on the south slope of the Iceland Faroes Ridge running
towards the Faroe Bank Channel. This was completed by mid morning 20th (201)
and then course was set towards a repeat of Saunders line Q from Charles Darwin
Cr42.
Time was by now running short and the shallowest station of the line was
omitted. There was insufficient time also for the last/deepest station and
instead of this the last two T5 XBTs were deployed. The section was completed
by 2000Z 20th (201) and course set for the Pentland Firth.
Passage continued throughout the 21st in good weather. A further ADCP
calibration run was performed west of Orkney during a period of good GPS data.
The PES was recovered and course resumed towards Aberdeen.
The vessel docked in Aberdeen 0930A/22nd(203). The following day was spent
with a film crew from Shell producing footage for a film on Climate Change.
WJG
REPORTS OF SCIENTIFIC WORK.
CTD Operations
During RRS Charles Darwin Cr 50, a total of 57 CTD stations were
worked.
This was the first cruise on which the new Neil Brown CTD deck units and
Rosette Multisampler deck units were used. A new 10 litre 24 bottle Rosette
Multisampler was employed throughout the cruise but with only 12 bottles in
alternate positions around the rosette.
The total package was made up of a NBIS MkIII CTD with dissolved oxygen sensor
and a 1m path length transmissometer. These were mounted horizontally in a
protective frame below the rosette. A 10kHz pinger with tilt indicator was
mounted in the CTD frame.
The horizontal attitude of the CTD made it extremely easy to mount and
service. Two lead weights of approximately 40kgs each were secured to the
frame to help overcome the drag of the rather large package.
Although the package is large, in use it proved very easy to handle. The 12
10 litre water bottles were used for most of the casts. These were mounted at
alternate positions around the frame to provide a balanced package.
7 SIS digital reversing thermometers and 2 reversing pressure meters were used
with the bottles.
The pairing of thermometers was changed on a number of occasions, in order to
determine calibration errors. (See separate section)
Water sampling was carried out on deck with the bottles mounted permanently on
the Multisampler.
During the first cast it became apparent that there was a serious problem with
the conductivity cell. It was not clear if the problem was one of fouling or
just failure. A new cell was fitted for the remaining casts.
The new deck units and acquisition software generally worked extremely well
and were easy to use. However there was a problem on a number of occasions
with the system crashing after the start of an upcast when trying to fire the
first water bottle. It was believed to occur when bottles were fired too soon
after the end of the down cast. Due to the method used to save the raw data,
none was lost on these occasions.
The CTD and transmissometer worked throughout the cruise without fault. The
pinger tilt indicators showed that the package rotates slowly during the cast
but this did not create any problems.
The new articulated arrangement of the CTD A frame made handling the package
both easy and safe, although weather conditions were never bad enough to really
test the system. Cable loading on the 8 mm CTD wire could be a problem with
the ship heaving in heavy seas.
The sea cable had to be reterminated twice during the cruise due to its
snagging on the shackle at the top of the CTD.
The bottle files generated by the PS2 system were copied to disk and merged
with sampled salinity and nutirient data on the Sun workstation.
After problems on the first station the stability of the replacement
conductivity cell was found to be very good, providing an excellent set of data
for the cruise. The high quality of the calibrations obtained were believed to
be due to a combination of good sampling technique, the use of new salinity
sample bottles and the new 10 litre water bottles.
CTD stations are listed on Table 1.
JS
Water sampling and salinities
Both IOS Guildline salinometers, the new and the old, were carried on this
cruise in the Charles Darwin's constant temperature laboratory set at
20C with salinometers set to run at 21C. Both were kept up and running, but
almost all sample processing was carried out on the old one, as the new one
gave indications of instability at the start of the cruise. When work
commenced, time did not permit the further investigation of this indication. A
few checks suggested that the new one was working at least adequately, but I am
not yet confident that it is as reliable as the old machine, which performed
excellently, being in nearly continuous use for ten days and only wandering
twice.
A total of 981 samples were processed, comprising 430 duplicate pairs of
bottle samples, 72 single bottle samples and 49 surface samples from the
non-toxic supply. Reproducibility between duplicates was of a high standard,
with 202 pairs 0.000 different in salinity, 195 pairs 0.001 different, 24 pairs
0.002 different and 1 pair each at 0.003, 4, 5 and 6. The two worst pairs
result from the salinometer's two wanderings.
I believe the quality of these results to be due to three things. Firstly,
the increased frequency of standardisation: once every twelve samples (start,
middle and end for a crate of 24 samples); secondly, the ten-litre GO bottles,
being of large volume, make the sample water less susceptible to contamination
from leaks; and thirdly, the new sample bottles. It is surprising that,
considering their cheapness (79 pence per bottle), they have not been replaced
earlier and more often. The old bottles with their one-piece tops were
contaminated and deteriorating. The new bottles are of fine clear glass with
disposable stoppers (3 pence each), ensuring a clean seal with no need to worry
about cap contamination from previous samples. Unfortunately some stoppers had
to be re-used, as adequate supplies were not available for this cruise. None
was used more than twice on this cruise. They should be disposed of upon
return and a large (ca 10,000) supply purchased soon.
Sampling was carried out on deck. A bonus from this which excluded further
contamination was that the sample bottles were kept in the wet lab, separate
from the GO bottles, so that they were not swimming in the spill water from the
GO bottles as they would have been had the old fiddle been used. Sample
bottles should be kept separate from GO bottles at all times to improve
cleanliness. Furthermore, upon return, all used sample bottles will be washed
clean and dried. Storing them with seawater inside for the best part of each
year can only hasten deterioration and increase the risk of contamination.
With regard to standardisation, 130 ampoules of Standard Seawater batch P113
were consumed on this cruise. Some defects in the SSW must be noted here.
i. Three ampoules were seen to contain 'floaters', small specks of foreign
matter, one seen after opening but two before.
ii. One ampoule had not been sealed correctly; upon opening one end, the water
poured out of the other.
iii. Most worryingly, two standards were found which were way off salinity.
P113 has K15 = 0.99984, ie a Guildline ratio of 1.99968. The old
salinometer was set to read SSW at or about this value, with drifts typically
of +/- 0.00010. The two suspect ampoules gave ratios of 1.99999 and 2.00050,
both confirmed as wrong by immediate re-standardisation.
The changes in standardisation throughout the cruise are presented in
Figure 1.
It is to be hoped that noted drifts were due to the salinometers, and not to
less extremely erroneous SSW. It may be possible to use the duplicates as a
check on the standardisation. This will be attempted in the near future.
Salinity determination from Guildine ratio was performed on the cruise using
Ocean Scientific International's software package "Salinity". An IBM PS/2 was
used to run the package.
SB
Nutrient determinations
Analyses for silicate, nitrate and phosphate were carried out on CTD water
bottle samples from Stations CD50001 to CD50053 on the Alpkem RFA 300
autoanalyser and Stations CD50001 to CD50057 on the IOSDL autoanalyser. Some
samples were frozen for later comparison in the Lab.
The IOSDL system worked well throughout the cruise, and we expect the primary
nutrient data to be from this system. The majority of problems experienced
using the Alpkem were caused by the lack of a manual for the software. Using
the Help screens it was finally possible to process the data collected.
Nitrate: comparing the two systems the results agreed to within
1%. The Alpkem system worked well, especially the new type of open tube cadmium
reducing reactor which needed very little attention.
Silicate: Comparing results between the two analysers the results were
3-5% different.
Phosphate: The phosphate channel on the Alpkem was not satisfactory due
to problems with noise on the signal, possibly caused by the tubing or bubbles,
the latter could be improved by inserting a de-bubbler before the flow-cell.
The other main problem with the phosphate was drift in the baseline.
There are still some features of the system not tried out, eg. carry over
corrections from one sample to the next. The phosphate channel needs to be
improved and then the Alpkem will be a good system to use at sea, as each
sample uses 2ml of seawater and only takes 70s to sample.
Jill S
Oxygen Determinations
During Cruise 50 it was intended to perform an intercomparison study between
oxygen titration equipment supplied by UCNW Bangor and a new fully automatic
unit recently purchased by IOSDL Marine Physics.
Due to a fault with the stabilised power unit, it was not possible to obtain
results from the UCNW equipment.
The results obtained from the Marine Physics unit were on the whole good. Some
problems were experienced with air locks trapped in the burette system which
appeared to be due to a faulty seal. With practice it should be possible to
reproduce results to a precision of 0.05%,which would be adequate to meet WOCE
standards and allow comparison between data sets.
The equipment accuracy has also been improved since, supplied with a standard
of known concentration, the unit will calculate the titre normality and so
eliminate inaccuracies in calculation due to preparation of solutions.
500 samples were taken during the cruise and analysed in duplicate. The
preparation and analysis time is rather long and the software supplied with the
unit has space for only 100 sample bottle volumes. It was therefore only
possible to have four sets of samples awaiting analysis. With the high
frequency of CTD sampling it was difficult to maintain a supply of clean
bottles.
The procedure should be improved by adjusting the software to accommodate a
larger bottle bank and obtaining more sample bottles.
RP
Aluminium determinations
Dissolved aluminium concentrations are higher in deep waters than in
intermediate waters. The source of this aluminium has not yet been identified.
One proposed mechanism has been the dissolution of aluminium from particulate
aluminosilicate material resuspended into waters containing low concentrations
of dissolved silica in areas of strong bottom currents such as those
encountered on this cruise. Aluminium has also been suggested to be a useful
identifier of water masses giving additional information to that which can be
gained from the traditional measurements of temperature and salinity and from
nutrient determinations. The analysis of the results from the detailed
sampling carried out on this cruise will allow us to determine if aluminium is
a useful tracer of high latitude water masses.
Aluminium determinations were made on 357 samples of unfiltered water out of a
total of 499 water samples collected on the cruise. 65 determinations were
also made on samples filtered through 0.2 micron pore size filters.
The concentrations measured ranged from 75nM in unfiltered deep waters with
high particle concentrations to 2nM in biologically depleted surface waters.
The precision of the analyses was good on this cruise being consistently better
than 0.5nM.
Concentrations are higher in the Norwegian Sea than in the Iceland Basin at
1000m water depth. Contouring of the concentrations shows a distribution that
follows the density distribution across the Iceland-faroes Ridge.
Concentrations in the Iceland Basin correspond closely with those determined at
the Southern end of this basin on the BOFS-3 cruise in 1989. Dissolved
concentrations are markedly higher in waters with high suspended matter
concentrations in deep water. However the suspended matter in these waters
contains aluminium which is detected by the fluorometric determination used.
(This is not the case in surface waters with high suspended matter
concentrations, and most previously reported determinations of aluminium in
deep sea waters have been done on unfiltered samples). The aluminium
concentration increases more rapidly close to the bottom than does the silica
concentration. This suggests that there is some dissolution of aluminium
taking place in the nepheloid layer rather than the increase being due to a
change in the identity of the water mass.
DJH
Digital reversing thermometers
The SIS digital reversing thermometers and pressure meters were paired on four
of the twelve bottles used. For the most part there were pressure
determinations at the maximum depths reached and temperatures determined at the
top, bottom and two intermediate depths. Pairings of thermometers were changed
throughout the cruise to enable intercomparisons to be made. The levels chosen
for firing the bottles tended to be selected on the basis of providing good
vertical distributions of nutrient data rather than for being in areas of low
vertical temperature gradient.
Table 2 shows difference between pairs of digital thermometers, corrected
using the manufacturer's calibration data. Only 3 pairings show offsets
significantly different from zero (401-220, 400-220, 238-204). Comparisons
with data from other pairs does not allow one to conclude that any particular
thermometer calibration is in error but suspicion falls on 220 and 204.
Table 4 shows the difference between the pressure meters and the CTD. 204
shows a large but not statistically significant offset, as also do 398 and 401.
Again thermometer errors cannot be unambiguously identified.
Table 4 shows the difference between the pressure meters and the CTD. These
in each case demonstrate a pressure (or possibly temperature) dependence.
WJG, MW
XBT measurements
The cruise was the first on which the Hydrographic department's XBT system was
used. It consists of a Bathysystems SA-810 XBT unit interfaced to a Zenith
personal computer and with a satellite data link to the Meteosat satellite.
The recording unit was installed in the plot, abaft the bridge, and
communication between the plot and the afterdeck was by means of portable VHF
sets. This proved less than satisfactory since there were a number of "dead"
spots in the plot from which communication was difficult. The recorder was
connected to a Plessey plug mounted on the after external bulkhead of the main
lab. Initially there were a number of probes which failed to record good data
due to an apparent earth leak on the hand held launcher. After this had been
replaced there were few failures. We noted an number of problems with the XBT
software:
The timeout period between setting up the recording unit and having to launch a
probe is too short for a vessel on which the recorder and launcher are so far
from oneanother.
More seriously the algorithm for coding the JJXX satellite message ignores
information input to the program which specifies a depth at which the probe hit
bottom and below which date are in error. This resulted in apparently
subbottom data with spurious temperatures being transmitted.
Towards the end of the cruise a considerable number of probes were dropped
close to the 700m contour on the south side of the Iceland Faroes Ridge. A
comparison of indicated bottom depth from the XBTs (Plessey T7s) and the
corrected depth determined from the echo sounder showed that the XBT depths
were shallow by 37.4+6.6m. An analysis of the data for probes used in
shallower water depths suggests that a linear relationship between zero error
at the surface and 40m at 700m would nowhere be in error by more than
+10m. In all cases probes were dropped with the ship speed between 8
and 12 kts.
Details of all XBT drops are given in Table 5:
Fig. 2 shows the observed depth errors (True depth - XBT depth) .
WJG
Ship mounted ADCP
A vessel mounted ADCP (RDI, 150kHz) was run between 1800Z/181 and 1900Z/182
prior to the rudder repairs and from 1753A/190 until 2359Z/202. Three
configurations were used
a) bottom tracking in depths less than 200m
b) bottom tracking in depths to 800m
c) water tracking
During the cruise regular notes were made of clock error with respect to the
vessel's master clock. The ADCP clock was reset every 2.5 days (approx) when
the error reached of order 1 minute. Checks of the ADCP temperature against
the ship's hull temperature sensor showed there to be good agreement. Checks
were also made against the ship's gyro-compass. Heading differences of 1 or 2
degrees were seen at times .
Data were collected in 2 minute ensembles, transferred in 24 hr segments to RVS
data files and thence into the Sun Pstar system. At this stage a number of
operations were carried out on the data:-
a) water track and bottom track segments were separated
b) velocity units were converted to cm/s
c) header information was input
d) times were corrected for clock error and converted to seconds
e) missing data values were converted from 1999 to -999
f) data with % good less than 25% were set to absent data
g) the data were corrected with a pointing angle and scaling factor.
These last corrections were derived fom calibration runs carried out using the
method of Read and Pollard (see narrative section). The two calibration
exercises produced rather different and noisy values for A and phi as follows
:-
Day 191 A = 1.011 Phi = 0.652
Day 202 A = 1.122 Phi = 0.016
When the vessel was on station during CTDs, wire tests and mooring
deployments, time series of data were identified and plotted. It had been
hoped to collect ADCP data on station and over complete tidal cycles near
temporarily deployed current meter moorings but the loss of time with rudder
problems precluded this. All data files were archived for later processing at
IOSDL.
KM
Mooring Operations
Seven current meter moorings with 13 Aanderaa current meters were deployed S.E
of Iceland for a period of one year in water depths ranging from 1027-2305m.
The mooring positions were in deeper water than had been planned in light of
the results from a CTD survey to detect the cold water overflow.
An Acoustic Doppler Current Profiler (ADCP) mooring was deployed at 64 23.8N
,11 55.7W which is to be recovered on Charles Darwin 51.
All Aanderaa current meters had been overhauled and calibrated at IOSDL prior
to the cruise and cold tests carried out to ensure correct operation at
expected working temperatures. Fins were overhauled and fitted with titanium
spindle assemblies in an attempt to overcome corrosion problems experienced
during previous one year-long deployments. The ADCP and S4 current meter were
provided by RVS and were already prepared and working when received.
Mooring deployments were carried out using the RVS portable double barrel
capstan (DBC) winch with the line leading over a snatch block attached to the
hook on the starboard Effer crane. The Effer cranes on the stern are a recent
addition to the Charles Darwin and provide an excellent alternative to the A
frame for mooring deployment/recoveries. A length of 13mm chain was also
attached to the hook to "stop off" the mooring line as required.
The Aanderaa current meter moorings were all deployed anchor first and the
line stopped off as required for instrument insertion. Difficulties were
experienced with the haul/veer control on the DBC when minor adjustments were
required but generally all deployments were straightforward. It is recommended
that in future the DBC drums should not be painted so as to improve traction.
The ADCP mooring was deployed ADCP first, the method dictated by the
construction of the buoyancy package. All lines and instruments were
preassembled on deck prior to deployment, with the release and Aanderaa current
meter suspended from the block and secured by the line to the DBC. The ADCP
and S4 current meter were lowered to the waterline on the port Rexroth winch,
cut away and allowed to drift astern as the ship increased speed to 1.5-2
knots. The glass spheres were lowered by hand as the line tightened and the
tension was finally taken by the DBC, allowing the release and current meter to
be lowered away. Finally the anchor was fitted and cut away at the
waterline.
Mooring details are given in table 6.
KG
Mooring Acoustics
Seven moorings were to be deployed for at least one year. Over the last
fifteen years about one long term mooring a year has `vanished', that is, no
acoustic contact has been made with the acoustic release and relocation unit.
In view of this and the age of current release stocks, one third over eight
years old and one third brand new, I decided to double up acoustic units on
each mooring. The proposed mooring depths ranged smoothly from 200 metres to
2350 metres and so I planned to deploy four pairs using `shallow ceramic ring'
acoustic transducers and three pairs using `deep mushroom' acoustic tansducers.
The physical oceanography of the area dictated a last minute change of plan to
a deeper deployment pattern. With no time to prepare extra deep units I
altered the pairings so that two of the moorings that were marginal for shallow
transducers were covered by a transducer of each type.
My original intention of using transponders to mark two of the moorings was
frustrated by the destruction of one set of electronics by a faulty Lithium
cell. This is the second known failure of a cell of this type (Crompton
Parkinson G20) in recent months. It is particularly worrying as this cell is
used in the acoustic release battery pack although no known failures have
occurred in the ten years we have been using them in that application.
A short term (four to six weeks) deployment of a mooring carrying an acoustic
doppler current meter, an electromagnetic current meter, and a conventional
rotor current meter was proposed. As the total value of this rig was about
[[sterling]]100,000 I decided to pair both the IOS type acoustic units provided
by RVS for this mooring. On inspection of the electronics it was obvious that
neither unit had been adjusted from new. Both units required significant
adjustment before I was happy to deploy them.
A very short term mooring (multiple deployments of 12 to 14 hours) was
proposed .This was covered by the spare units prepared and tested for the long
term moorings.
The acoustic units were wire tested at about their proposed operating depth
and temperature in groups of four on six deployments. One new unit required
three tests before I was happy with it, five other units required a second test
after adjustment.
All Releases were fitted with two pyroleases.
GP
Simrad Precision Echosounder
This unit was run throughout the cruise mainly in a passive `Pinger' mode
using the hull mounted acoustic transducer. I will be reviewing the system
further on Discovery Cruise 194; these are my impressions so far.
Generally the three parameters controlling receiver gain are far too complex;
two of them could be locked to maximum values for most cruises and gain
controlled in simple 3db steps using the third. I have not yet played with the
external triggering mode.
1. As a passive monitor it worked well. The ability to use either the VDU or
the printer as an expanded window is potentially very useful.
There are two major drawbacks.
a) The scale the output is drawn on both VDU and printer is not controlled by
the input sound velocity profile as far as I can see. They both appear to be
scaled to the default 1472 metres per second - this is not acceptable.
b) The signal appears to be sampled only one in seven sweeps; that is two
seconds in every fourteen. This is unacceptable for most monitoring work,
particularly close bottom approach work.
2. As an echosounder also monitoring pingers - essential for all bottom and
near bottom approach work - it's sophistication is it's downfall.
a) It can be made to repeat at a precision rate but this involves setting a
rate longer than the expected bottom reply. In deep water this can be ten
seconds so setting a two second window to monitor a pinger with reasonable
resolution involves only sampling one sweep in five - this is unacceptable.
b) If the software detects a signal of similar amplitude to the expected bottom
echo it spends time analysing it and then locks on to it's preferred source.
During this time it loses it's precision timing and so all signals are
scrambled - this is unacceptable. When it relocks it starts a new sequence so
all pinger signals are displaced. It will also then track the pinger signal as
the depth so the digital reading will be wrong although the true bottom echo
will be obvious to the observer and readable from the scale lines. The
resolution readable to the unaided eye on a 1500 metre display is 10 metres at
best - this is not really acceptable.
c) Removal of TVG from echosounding mode appears to have resulted in a
monochrome (red) display. This reduces the dynamic range of the display and
therefore an easy to use gain control is required.
GP
Level A/B/C computing
Data was logged from the following systems:-
Em log - no problems.
Gyro - when sailing north the synchro output from the gyro produced
spurious readings when swinging from 0 to 360 degrees and back. It is thought
that the stators need adjusting or cleaning. This will have to wait until
suitably skilled staff can attend the vessel.
MX1107 - no problems although it was noticed that the bridge officers
frequently relied on the MX1107 in preference to the GPS. The provision of a
Navigation Display Unit for the GPS is needed particularly now cover is
improving.
GPS - North of about 60N GPS gives almost continuous cover with 3 or
more satellites in view for all but two short periods each day. Statistical
analysis of GPS data from periods in port have revealed that despite the
rubidium frequency standard, fixes derived from 2 satellites are significantly
worse than those derived from 3 or more satellites. The degradation now applied
to the GPS data gives typical errors of about 45m. in latitude and 95m. in
longitude.
The Level A itself developed a fault on the local terminal output and this,
together with the occasional spontaneous reset, may mean it is prudent to
replace the hardware for the next cruise.
TSG103-no problems.
CTD-no problems.
ADCP - Logged directly into the parser SUN 3/60. This suffered from the
same synchro gyro problem mentioned above.
Plot Network ( Cambridge Ring ) Server.
This has an intermittent fault that has as yet not been traced. There is a
spare available for the next cruise.
Level B performed well with no crashes.
There were no problems with the level C but some of the ASCII terminals are
showing symptoms of age. The bulk of the processing was done in Pstar. The
transfer between RVS data file and Pstar (datapup) was initially a problem but
advice from colleagues on Discovery during a routine radio schedule solved most
of the difficulties.
RBL
PSTAR Data Processing
The on board Sun Microsystem network was loaded with the Pstar library which
was compiled and used successfully throughout the cruise.
The problems encountered on Discovery 189 with tape archiving were not present
and around 200Mb of data have been archived to tape and brought back to
IOSDL.
The RVS program DATAPUP caused some difficulties. The program transfers data
from RVS level C to IOSDL Pstar format. The problem arose when a file was left
open after being written to by an instrument. It was assumed that in leaving
the file open the file pointer was not sure of its exact position and so
transferred no data. When files were closed after being written to the problem
disappeared.
The processing of CTD data from the 57 stations on Darwin 50 was similar to
that used on Discovery 189. Differences in processing were mainly caused by the
introduction of the new CTD deck unit which made part of the old data route
redundant.
The processing was therefore mainly accomplished using the existing execs ( an
exec is a collection of Pstar programs that run together in sequence ).
CTDEXEC0 reads in the data from an RVS file. This sometimes caused problems
from the program datapup.
CTDEXEC1 performed a calibration on the data. Three calibration files were
used throughout the cruise with modifications being made to the pressure and
conductivity calibration values
CTDEXEC2 was used to extract the down cast from the ctd station.
CTDEXEC5 was modified to produce less derived variables and averaged the data
on 2db intervals.
Considerable time was spent on working through the method used on Discovery
189 (CTDEXEC4 ) to correct the salinity values but because of time restrictions
this was left until the return to IOSDL. Potential temperature against salinity
was plotted for each CTD station. The data was gridded and plotted in sections
for temperature, salinity and sigma. The sections were plotted out as below.
Stations Calibration No of stations file no. CD50001 1 1 002-020 1 19 021-037 1 17 038-042 2 5 043 2 1 044-053 3 10 054-057 3 4The data was archived all the way through the process. The full data processing route for each station is as below :-
CTDEXEC0- archived copy- CTDEXEC1- archived copy- CTDEXEC2- archived copy- CTDEXEC5- archived copy- griddded into sections
The method used on Darwin 50 for the display of nutrient data is different to
that used on any previous cruise mainly because of the introduction of the new
CTD deck unit.
For each CTD cast the deck unit creates a "bottle" file. This file contains a
header. The header contains a unique label for each CTD station, the
geographical position and the time of the cast. The file also contains CTD data
from each of the sensors averaged about the time at which a bottle was fired.
It has one such line for each bottle firing. For example in normal use the
bottle file had 24 lines, one for each space in the rosette whether it had a
bottle in it or not. A misfire when trying to close a bottle would appear as
an extra line of data in the bottle file.
Each bottle file was edited using the Sun microsystem screen editor. The
header was deleted as were any lines of data that did not correspond to a
bottle on the rosette sampler. The variables that were not used in Darwin 50 (
eg fluorescence ) were deleted. There then remained a bottle file that just
consisted of the following 8 variables
Salinity- Bottle number- Oxygen Current- Pressure- Oxygen temperature- Temperature- Dissolved oxygen- Conductivity.
The next stage was to bring in the nutrient data, the bottle determined
salinity and dissolved oxygen. Using the hydrographic log sheets and the
unique sample number that was used on this cruise for each bottle, it was a
simple matter to piece the correct sample data to the correct line in a bottle
file using the basic Sun editor facilities (cut, copy,paste)
Each bottle file now contained 16 variables in an ASCII file:-
Bottle number- Sample Number- Pressure- Sample O2- Temperature- Sample salinity- Conductivity- Aluminium- Salinity- Filtered aluminium- Oxygen current- Nitrate- Oxygen temperature- Phosphate- Dissolved oxygen- Silicate
This file was read into Pstar format using the Pstar program PASCIN, thus
creating one Pstar file for each CTD station. Once in this format it was easy
to grid and plot the nutrient data in a similar form to that used in the CTD
sections. Although this was a simple part of the processing it was extremely
time consuming and hopefully the more experienced personnel on Darwin 51 will
come up with a less time absorbing way of displaying nutrient data.
As the files created using the method above contained a raw conductivity value
and a bottle salinity value ( assumed to be correct ), a new value for the
conductivity could be calculated. This new conductivity value could then be
divided by the old value to derive a ratio. This ratio is called the corrected
conductivity ratio and is used in the CTD calibration files ( see ctdexec1 ). A
Pstar program was written to work out this corrected conductivity ratio (
CRAT.F), and write the results to a file. The file was then analysed by
calculating a mean and standard deviation of the conductivity ratios to see
just how the conductivity ratio changes with time. At sea this was only done on
the first 20 stations, but showed that the previously used conductivity ratio
of 0.99987 was wrong and a much better value would in fact have been 1.0002.
The calibration file in CTDEXEC1 was changed on the basis of this result. It
was felt that the results showed promise but as with the nutrient data the
main problem was a time consuming method of getting to them.
MAB
ACKNOWLEDGMENTS
This cruise was severely disrupted by problems with the vessel's rudder which
necessitated three unscheduled port calls and two periods in dry dock; all this
before any work had been done. It says much for the forbearance of all the
ship's personnel, scientists, officers and crew that so much was achieved in
the remaining ten working days.
TABLE 1
CTD Station list
Conse- Time Day/ Lat Lon Water Closest Comments cutive Down Date 1990 N W depth Approach Number z m m 1 0845 192(11-7) 60 10.5 6 03.8 1212 33 FS1 All bottles fired at bottom 2 1940 193(12-7) 60 29.0 12 41.9 405 14 IB1 3 2118 193(12-7) 60 33.7 12 53.1 602 7 IB2 4 2319 193(12-7) 60 39.0 13 03.0 1045 16 IB3 5 0125 194(13-7) 60 44.2 13 13.2 1440 15 IB4 6 0351 194(13-7) 60 50.3 13 25.8 1667 18 IB5 7 0627 194(13-7) 60 55.1 13 36.2 1675 10 IB6 8 1001 194(13-7) 61 07.9 14 06.5 1759 7 IB7 Computer crash on way down 9 1355 194(13-7) 61 23.3 14 35.6 2070 15 IB8 10 1812 194(13-7) 61 36.3 15 6.8 2157 1 IB9 11 2158 194(13-7) 61 49.7 15 36.1 2290 14 IB10 12 0714 195(14-7) 62 03.7 16 03.6 2218 8 IB11 13 1033 195(14-7) 62 17.8 16 18.9 2120 13 IB12 14 1540 195(14-7) 62 30.0 16 33.7 2065 9 IB13 15 1825 195(14-7) 62 41.3 16 47.4 1830 8 IB14 16 2043 195(14-7) 62 48.3 16 54.1 1675 9 IB15 17 2312 195(14-7) 62 54.0 17 00.9 1550 9 IB16 depth approximate, not observed 18 0150 196(15-7) 63 00.4 17 08.1 1297 13 IB17 19 0432 196(15-7) 63 12.6 17 12.6 1322 8 IB18 20 0714 196(15-7) 63 12.0 17 22.1 660 10 IB19 21 0020 197(16-7) 62 10.4 15 31.8 2222 8 T1 22 1425 197(16-7) 62 19.2 15 04.0 2030 12 T2 23 1827 197(16-7) 62 28.0 14 38.9 1761 8 T3 Second attempt after cable failed 24 2132 197(16-7) 62 37.9 14 10.1 1465 8 T4 25 0026 198(17-7) 62 47.0 13 41.6 1120 15 T5 26 0302 198(17-7) 62 56.6 13 14.3 820 7 T6 27 0520 198(17-7) 63 05.6 12 46.6 535 6 T7 28 0723 198(17-7) 63 14.2 12 19.6 435 10 T8 29 0945 198(17-7) 63 23.1 11 52.0 410 5 T9 30 1210 198(17-7) 63 33.2 11 24.9 322 7 T10 31 1412 198(17-7) 63 42.1 10 55.8 385 5 T11 32 1621 198(17-7) 63 51.5 10 27.0 518 8 T12 33 1827 198(17-7) 63 59.9 10 00.5 646 8 T13 34 2043 198(17-7) 64 09.1 09 31.5 890 6 T14 35 2308 198(17-7) 64 18.3 09 02.6 1010 12 T15 Computer crash at bottom 36 0143 199(18-7) 64 27.5 08 31.3 1040 12 T16 37 0415 199(18-7) 64 31.6 08 19.0 2380 10 T17 38 1840 199(18-7) 64 22.1 12 27.3 243 11 C1 39 1947 199(18-7) 64 19.3 12 18.7 465 8 C2 40 2057 199(18-7) 64 16.2 12 10.5 446 7 C3 41 2213 199(18-7) 64 13.0 12 02.8 425 7 C4 42 2319 199(18-7) 64 10.0 11 54.6 383 7 C5 43 0147 200(19-7) 64 01.4 12 24.7 490 7 Alliance intercomparison 44 0837 200(19-7) 63 42.9 14 24.0 310 9 O1 45 0941 200(19-7) 63 42.2 14 22.1 700 10 O2 46 1121 200(19-7) 63 37.0 14 15.9 1180 14 O3 47 1315 200(19-7) 63 30.7 14 08.0 1415 10 O4 No O2 samples 48 1512 200(19-7) 63 25.3 13 59.0 1337 7 O5 49 1706 200(19-7) 63 19.7 13 49.9 1305 7 O6 50 1903 200(19-7) 63 14.1 13 41.2 1190 7 O7 51 2044 200(19-7) 63 08.1 13 32.2 1005 9 O8 52 2224 200(19-7) 63 02.4 13 23.2 890 8 O9 53 2359 200(19-7) 62 56.5 13 15.0 825 10 O10 Repeat of T6 54 1333 201(20-7) 61 53.6 09 05.3 585 10 Q5 55 1503 201(20-7) 61 48.8 09 16.7 730 12 Q4 56 1708 201(20-7) 61 43.7 09 26.1 860 10 Q3 57 1853 201(20-7) 61 38.7 09 36.9 1000 37 Q2 High shear near bottom Note depths are as recorded by the ship's PES. Sound speed is assumed at 1500m.sec-1. Designation T4 indicates 4th station on section T (see Figure 3).
TABLE 2
Differences between pairs of digital reversing thermometers (mK x 1000)
Pair of Thermometers Number mean Standard deviation Standard error
400-398 7 -0.83 3.4 1.29
401-238 9 -0.143 2.27 0.76
220-204 7 1 5.35 2.02
399-238 7 -1.29 3.73 1.4
398-238 14 2.36 2.3 0.61
401-220 4 6.25 0.96 0.48
401-400 23 1.43 4.98 1.04
400-220 15 6.6 3.29 0.85
238-204 8 6.25 3.5 1.24
399-398 8 0.375 1.92 0.68
399-204 8 3.75 10.95 3.87
TABLE 3
Differences between digital reversing thermometers and CTD (DRT-CTD) mK x 1000
Thermometer Number of mimimum maximum mean Standard Standard error
samples Deviation
204 21 -50 8 -6.63 12.44 2.71
220 37 -44 43 -0.96 14.7 2.42
238 33 -60 54 -0.55 22.95 3.98
398 21 2 44 12.35 11.69 2.55
399 23 -32 21 -0.99 13.88 2.89
400 37 -31 31 3.73 10.26 1.69
TABLE 4
Differences between CTD and digital pressure meters
6132H P<500 5001500 overall
mean 0.5 1.4 4.6 7.2 3.2
standard deviation 2.1 1.6 2.6 0.8 2.0
number 10 13 14 7 44
(965 +/- 185)
6075S P<500 5001500 overall
mean -3.6 -1.1 3.0 2.8 0.7
standard deivation 2.0 2.6 3.6 6.2 4.0
number 7 12 12 11 42
(1135 +/- 185)
TABLE 5
XBT Station list
TABLE 6
Seq File Day/ Time Lat Long Max Water Probe No No Date z N W Depth m Depth m No 1 test 2 test 3 Weight dropped off probe plx043441 73A 192(11-7) 2049 60 19.0 08 00.0 692 740 plx042444 4 74a 193(12-7) 0444 60 21.0 09 42.0 *** 1060 plx043442 5 75a 193(12-7) 1511 60 26.0 11 27.0 *** 1210 plx043445 6 56a Failed, wire blew onto ship 7 77a Noisy 77b Noisy 77c Test probe Changed launcher 8 58a 197(16-7) 1600 62 23.9 14 51.9 *** 1900 208178 9 59a 197(16-7) 2002 62 33.4 14 24.4 1645 1628 208185 10 510a 197(16-7) 2300 62 42.0 13 56.0 1305 1265 208180 11 511a 198(17-7) 0201 62 53.2 13 25.6 968 955 208188 12 712a 198(17-7) 0415 63 01.5 12 58.2 612 650 ???? 13 713a 198(17-7) 0622 63 10.3 12 33.2 440 470 plx043448 14 Failed at 50m 15 u/s 16 716a 198(17-7) 0838 63 18.9 12 02.8 381 410 plx04377? 17 Fouled ship 18 718a 198(17-7) 1114 62 28.7 11 36.4 352 373 plx043484 19 719a 198(17-7) 1315 63 39.3 11 11.1 335 345 plx043483 20 720a 198(17-7) 1517 63 46.8 11 40.1 444 465 plx043481 21 721a 198(17-7) 1725 63 13.4 10 14.7 540 585 plx043482 22 722a Suspect data plx043478 722b 198(17-7) 1946 64 04.7 09 45.9 *** 800 plx043478 23 523a 198(17-7) 2202 64 14.9 09 14.4 976 975 208189 24 724a Noisy plx043480 724b 199(18-7) 0024 64 23.1 08 46.9 *** 1090 plx043485 25 725a 200(19-7) 0859 63 42.6 14 23.0 462 500 plx043704 26 526a 200(19-7) 1013 63 41.5 14 20.5 993 970 208182 27 727a 201(20-7) 0058 63 00.5 13 04.6 646 700 plx043703 28 728a 201(20-7) 0129 62 57.7 12 54.4 617 650 plx043698 29 729a 201(20-7) 0159 62 54.2 12 45.4 632 677 plx043702 30 730a 201(20-7) 0229 62 51.9 12 35.6 683 696 plx043701 31 731a 201(20-7) 0259 62 49.6 12 25.2 652 691 plx043700 32 732a 201(20-7) 0329 62 47.2 12 13.5 652 689 plx043699 33 733a 201(20-7) 0359 62 44.9 12 02.7 648 694 plx043690 34 734a 201(20-7) 0429 62 42.5 11 51.7 651 695 plx043694 35 735a 201(20-7) 0500 62 40.1 11 40.6 658 690 plx043693 36 736a 201(20-7) 0529 62 37.8 11 29.8 640 687 plx043443 37 737a 201(20-7) 0559 62 35.5 11 18.8 654 685 plx043697 38 738a 201(20-7) 0629 62 33.1 11 08.0 657 700 plx043695 39 739a 201(20-7) 0659 62 30.7 10 56.8 642 685 plx043562 40 740a 201(20-7) 0729 62 27.6 10 47.2 640 670 plx043563 41 741a 201(20-7) 0759 62 23.7 10 38.9 640 680 plx043564 42 742a 201(20-7) 0830 62 19.9 10 30.3 700 745 plx043572 43 743a 201(20-7) 0902 62 18.0 10 18.6 736 790 plx043571 44 744a 201(20-7) 0930 62 18.3 10 07.0 690 735 plx043565 45 745a 201(20-7) 1000 62 17.4 09 55.7 643 685 plx043568 46 746a 201(20-7) 1030 62 15.0 09 44.7 615 660 plx043569 47 547a 201(20-7) 1940 61 36.3 09 40.3 1060 1038 208181 48 548a 201(20-7) 2002 61 34.2 09 40.3 1085 1060 208183 Water depth is measured by the ship's PES with an assumed velocity of 1500 m/s. *** indicates probe did not hit bottom.
MOORING A 61 44.3N 15 23.9W 2290m
DEPLOYMENT COMMENCED 0810Z 16/07/90 COMPLETED 0823Z 16/07/90 ON BOTTOM 0837 16/07/90
CR2462 1.10 314-322/355-362 TRANSPONDER
ACM 7948 1 HR SAMPLE 8 RPC 1ST DATA 1200Z 09/07/90 ROTOR FREE O812Z 16/07/90 IN WATER 0816Z 16/07/90
MOORING B 63 08.6N 17 17.8W 1027m
DEPLOYMENT COMMENCED 0833Z 15/07 90 COMPLETED 0848Z 15/07/90 ON BOTTOM 0855Z 15/07/90
CR 2512 1.10 315-320/355-362 CR 2523 1.02 312-325/256-265
ACM 3727 1 HR SAMPLE 8 RPC 1ST DATA 1200Z 09/07/90 ROTOR FREE 0841Z 15/07/90 IN WATER 0841Z 15/07/90
MOORING C 62 59.91N 17 06.54W 1300m
DEPLOYMENT COMMENCED 1044Z 15/07/90 COMPLETED 1055Z 15/07/90 ON BOTTOM 104Z 15/07/90
CR 2521 1.08 313-327/434-449 CR 2522 1.06 312-326/453-467
ACM 5205 1 HR SAMPLE 8 RPC 1ST DATA 1200Z 09/07/90 ROTOR FREE 1047Z 15/07/90 IN WATER 1047Z 15/07/90
MOORING D 62 43.1N 16 49.2W 1800m
DEPLOYMENT COMMENCED 1405Z 15/07/90 COMPLETED 1438Z 15/07/90 ON BOTTOM 1449Z 15/07/90
CR 2520 1.12 316-323/415-424 CR 2400 0.94 312-322/333-343
ACM 6867 1 HR SAMPLE 8RPC 1ST DATA 1200Z 09/07/90 ROTOR FREE 1430Z 15/07/90 IN WATER 1433Z 15/07/90
ACM 3726 1 HR SAMPLE 8RPC 1ST DATA 1200Z 09/07/90 ROTOR FREE 1417Z 15/07/90 IN WATER 1433Z 15/07/90
ACM 2107 1 HR SAMPLE 8RPC 1ST DATA 1200Z 09/07/90 ROTOR FREE 1406Z 5/07/90 IN WATER 1410Z 15/07/90
MOORING E 62 26.38N 16 28.25W 2055m
DEPLOYMENT COMMENCED 1723Z 15/07/90 COMPLETED 1800Z 15/07/90 ON BOTTOM 1815Z 15/07/90
CR 2519 1.14 314-325/295-305 CR 2385 1.04 314-322/336-345
ACM 6225 1 HR SAMPLE 8RPC 1ST DATA 1200Z 09/07/90 ROTOR FREE 1752Z 15/07/90 IN WATER 1755Z 15/07/90
ACM 2108 1 HR SAMPLE 8RPC 1ST DATA 1200Z 09/07/90 ROTOR FREE 1738Z 15/07/90 IN WATER 1740Z 15/07/90
ACM 7945 1 HR SAMPLE 8RPC 1ST DATA 1200Z 09/07/90 ROTOR FREE 1724Z 15/07/90 IN WATER 1725Z 15/07/90
MOORING F 62 03.8N 16 03.3W 2235m
DEPLOYMENT COMMENCED 2113Z 15/07/90 COMPLETED 2136Z 15/07/90 ON BOTTOM 2154Z 5/07/90
CR 2557 1.00 316-323/453-467 CR 2499 1.12 315-324/374-386
ACM 8011 1 HR SAMPLE 8RPC 1ST DATA 1200Z 09/07/90 ROTOR FREE 2118Z 15/07/90 IN WATER 2132Z 15/07/90
ACM 3624 1 HR SAMPLE 8RPC 1ST DATA 1200Z 09/07/90 ROTOR FREE 2115Z 15/07/90 IN WATER 2118Z 15/07/90
MOORING G 61 49.9N 15 37.4W 2305m
DEPLOYMENT COMMENCED 1000Z 16/07/90 COMPLETED 1022Z 16/07/90 ON BOTTOM 1043Z 16/07/90
CR 282 1.04 313-322/353-366 CR 2417 1.18 314-326/394-405
ACM 2109 1 HR SAMPLE 8RPC 1ST DATA 1200Z 09/07/90 ROTOR FREE 1010Z 16/07/90 IN WATER 1017Z 16/07/90
ACM 4738 1 HR SAMPLE 8 RPC 1ST DATA 1200Z 09/07/90 ROTOR FREE 0958Z 16/07/90 IN WATER 1005Z 16/07/90
ADCP MOORING 64 23.8N 11 55.7W 435m
DEPLOYMENT COMMENCED 554Z 18/07/90 COMPLETED 1600Z 18/07/90 ON BOTTOM 1603Z 18/07/90
CR 2465 1.02.316-322/356-362 CR 2490 1.04 317-324/236-243
ACM 7401 10MIN SAMPLE 4 RPC 1ST DATA 1630Z 17/07/90 ROTOR FREE 1547Z 18/07/90 IN WATER 1600Z 18/07/90
END