CRUISE REPORT: ODEN91
(Updated JUL 2009)



HIGHLIGHTS

                              CRUISE SUMMARY INFORMATION

               Section designation  ODEN91
Expedition designation (ExpoCodes)  77DN19910726
                  Chief Scientists  Leif Anderson, Goteborg University
                                    J.-E. Hellsvik
                             Dates  17 August 1991 - 03 October 1991
                              Ship  Oden
                     Ports of call     
                                              90°N
             Geographic boundaries  15° 28'W          169° 41'E
                                             81° 8'N
                          Stations  52
      Floats and drifters deployed  unk.
    Moorings deployed or recovered  unk.
     Chief Scientists Contact Info  Leif Anderson, Professor • Dept. of Chemistry
                                    Göteborg University • 412 96 Göteborg • SWEDEN
                                    phone: +46 31-7722774 • fax: +46 31-7722785 
                                    email: leifand@chem.gu.se








             Arctic Ocean Expedition 1991 (ODEN-91)

        Revised Final Calibrated Pressure-Series CTD Data
(Pressure, Temperature, Conductivity, Salinity, Potential Temperature)

                 Processing Summary and Comments

                         August 8, 1998


                        STS/ODF CTD Group

                   Oceanographic Data Facility
               Scripps Institution of Oceanography
                  UC San Diego, Mail Code 0214
                        9500 Gilman Drive
                    La Jolla, CA  92093-0214
                      phone: (619) 534-1906
                       fax: (619) 534-7383
                   e-mail: marie@odf.ucsd.edu




Principal Investigators:

Investigator Paramater 
J.Swift      Hydro
G. Kattner   Nuts/O2
L Anderson   Nuts/O2
             TCO2
             TA
P.Jones      CFC




1.  CTD Processing Summary

     52 CTD casts were completed using a 24-bottle rosette
sampling system.  STS/ODF CTDs #4 and #6, modified NBIS Mark III-
B instruments, were both used during ODEN-91; CTD #6 was used
only for Station 5, cast 1 and CTD #4 was used for the rest of
the casts.  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 data were calibrated to salinity check
samples acquired on each cast.  The CTD time-series data were
then pressure-sequenced into 2-decibar pressure intervals.

2.  CTD Laboratory Calibrations

     Laboratory calibrations were done both pre- and post-cruise
for CTD #4.  CTD #6, which was used for only 1 cast at the
beginning of the cruise, had only pre-cruise laboratory
calibrations.

2.1.  Pressure Transducer Calibration

     Each CTD pressure transducer was calibrated in a
temperature-controlled bath to the STS/ODF Ruska deadweight-
tester pressure standard.  The mechanical hysteresis loading and
unloading curves were measured at cold temperature (-1.5 degrees
C bath for CTD #4 and 0 degrees C bath for CTD #6) to a maximum
of 8830 psi, and at warm temperature (30 degrees C bath for CTD
#4 and 28 degrees C bath for CTD #6) to a maximum of 2030 psi.

2.2.  PRT Temperature Calibration

     The CTD PRT temperature transducers were calibrated in a
temperature-controlled bath to an NBIS ATB temperature standard.
CTD #6 had 7 calibration temperatures measured, spaced across the
range of 0 to 28 degrees C.  CTD #4 had 9 points measured, from
-1.8 to 30 degrees C.  It should be noted that STS/ODF CTD PRT
temperature transducers are offset approximately +1.5 degrees C
in order to avoid a temperature response discontinuity that
occurs at 0 degrees C;  this offset is taken into account when
correcting the data.



3.  CTD Data Processing

3.1.  CTD Data Acquisition

     CTD data are acquired at a rate of 25 Hz.  Seven data  chan-
nels  (pressure,  temperature,  second temperature, conductivity,
dissolved oxygen, altimeter and elapsed time)  were  acquired by
CTD  #4.   CTD  #6  had  six  channels, with only one temperature
transducer.  The FSK CTD signal was demodulated by an STS/ODF-de-
signed deck unit and output to an RS-232 bus interface.  An Inte-
grated Solutions, Inc. (ISI) Optimum V computer served as the re-
al-time data acquisition processor.

     Data acquisition consisted of storing all raw binary data on
hard disk, then on magnetic cartridge tape, and generating a
corrected and filtered half-second average time-series.  Data
calculated from this time series were reported and plotted during
the cast.  A 3-second average of the time-series data was
calculated to correspond with each water sample collected during
the data acquisition.

     Generating the half-second time-series data set involved
applying single-frame absolute value and gradient filters, then
performing a 4,2 standard-deviation data rejection to all
channels.  During the acquisition, the pre-cruise laboratory
calibration data were applied to pressure and temperature.
Pressure, conductivity and oxygen were matched to the thermal
response of the PRT temperature transducer.  This lag time was
determined using raw CTD data from the cruise.  The conductivity
channel was corrected for thermal and pressure effects.

     During post-cruise processing, the CTD data were re-block-
averaged from the raw digital data and the CTD trip averages were
re-calculated.


3.2.  Pressure, Temperature and Conductivity/Salinity Corrections

     A maximum of 24 salinity check samples, were collected
during each CTD cast.  Discrete salts were analyzed on a
Guildline AUTOSAL using Wormley batch P-115 for standardization.
A 3-second average of the CTD time-series data was calculated for
each sample.  The resulting data were then used to derive CTD
conductivity/salinity corrections.

     There were difficulties at sea with the calculation of CTD
data averages at trip times.  Since a single-conductor wire was
used for the CTD casts, the bottle trip signals sent to the pylon
temporarily cut off power to the CTD.  It took several seconds
for the signal to stabilize after the CTD powered back up.  The
time needed for the CTD signal to steady again after power-up was
longer than normal due to a slightly improper CTD voltage/signal
strength adjustment.  Software was used to delay the CTD trip
average until 3 seconds after resumption of the CTD signal; 3
seconds being determined to be the optimal time for this data
set.

3.2.1.  CTD Pressure Corrections

3.2.1.1.  CTD #6

     The CTD #6 pre-cruise laboratory pressure calibration was
applied to the single CTD cast which used this CTD, since no
post-cruise laboratory pressure calibration was done.


3.2.1.2.  CTD #4

     The CTD #4 pre- and post-cruise pressure calibrations were
compared.  The cold/deep calibration curve shifted slightly over
1 decibar pre- to post-cruise, and the warm/shallow curve by less
than .5 decibar.  Pre- to post-cruise, the warm/shallow
calibration slopes were slightly different.  The pre- and post-
cruise pressure calibration data were averaged, and the resulting
pressure corrections applied to the data.  Offsets were adjusted
automatically for each station at the point where the CTD entered
the water.

3.2.2.  CTD Temperature Corrections

3.2.2.1.  CTD #6

     The CTD #6 pre-cruise laboratory temperature calibration was
applied to the single CTD cast which  used  this  CTD,  since  no
post-cruise  laboratory  temperature calibration was done.  There
was only one PRT for this CTD.

3.2.2.2.  CTD #4 (Revised)

     CTD #4 had two PRTs.  PRT-1 was the main temperature  sensor
and  was  used  exclusively  in all data processing.  PRT-2 was a
secondary temperature sensor installed to provide a check for the
primary PRT.  A comparison of the pre- and post-cruise laboratory
PRT temperature transducer calibrations showed an average  +.0066
degree  C  shift  for PRT-1, and no shift for PRT-2.  An analysis
was done of the temperature data between the two PRTs  throughout
the  cruise  to  see  if  the  relative  difference  between them
changed.  The differences between the two PRTs showed good agree-
ment with the post-cruise laboratory temperature calibrations, as
well as being consistent within a given station, and from station
to  station.   This indicates that the shift in PRT-1 most likely
happened before the cruise start, and that there was  no  further
shifting  of  the PRTs during shipment home.  Therefore the post-
cruise laboratory temperature corrections were applied to the CTD
data.

             *     *     *     Revision     *     *     *

     During the Arctic Ocean 94 expedition, the temperature cali-
bration applied to CTD #4 data on Arctic  Ocean  Expedition  1991
was questioned. It was thought that there was too much difference
in deep basin temperatures between the two cruises.  As indicated
in the above paragraph, there was some uncertainty as to when the
PRT calibration shift occurred for CTD #4.

     During the final processing for Arctic Ocean 94,  data  com-
parisons  were done for the 2 cruises for stations in similar lo-
cations, and the CTD #4 temperature correction applied for Arctic
Ocean  Expedition  1991 was re-examined.  Data were also compared
with preliminary results for Arctic Ocean 96  data.   Examination
of  the  PRT1-PRT2  differences during the cruise and between the
laboratory temperature calibrations led to a revision of the  CTD
#4  temperature correction for Arctic 91 CTD data.  The PRT1-PRT2
difference was .047 degrees for the pre-cruise  laboratory  cali-
bration, and .054 degrees for the post-cruise laboratory calibra-
tion.  The PRT1-PRT2 differences during the cruise held steady at
.052  degrees.  During final Arctic 91 post-cruise processing, it
was decided to use the post-cruise laboratory temperature correc-
tions  to  apply  to the CTD data, based on the interpretation of
steady PRT1-PRT2 differences during the cruise  which  were  much
closer  to post-cruise laboratory temperature calibration differ-
ences than pre-cruise.  It now seems likely that the  calibration
shift happened in 2 parts:  +.0044 degrees during shipping out to
the cruise, and the remaining +.002 degrees during shipping back.
Therefore it was decided to change the temperature correction ap-
plied to the Arctic 91 CTD data by +.002 degrees C (a less  nega-
tive correction), thus making the reported temperatures warmer by
2 millidegrees.
       *     *     *     *     *      *     *     *     *

3.2.3.  CTD Conductivity Corrections

3.2.3.1.  CTD #6

     Check-sample conductivities were calculated from the bottle
salinities using CTD pressures and temperatures.  The differences
between sample and CTD conductivities at all pressures were fit
to CTD conductivity using a linear least-squares fit to generate
a conductivity correction slope.  Residual conductivity
differences were then calculated and an offset was determined for
the single CTD #6 cast.

3.2.3.2.  CTD #4

     Check-sample conductivities were calculated from the bottle
salinities using CTD pressures and temperatures.  The differences
between sample and CTD #4 conductivities at all pressures were
fit to CTD conductivity using a linear least-squares fit.  Values
greater than 2 standard deviations from the fit were rejected.
The resulting conductivity correction slopes for each cast were
fit to station number.  It was determined to use a single,
average conductivity slope for all the casts.  Since the range of
conductivities in this part of the ocean is very narrow, the
conductivity slope correction does not have a great effect on the
data.

     Conductivity differences were calculated for each cast after
applying the average conductivity slope correction.  Residual
conductivity offsets were then computed for each cast and fit to
station number.  These offsets were evaluated for all pressures,
and for pressures below 950 decibars.  There was essentially no
difference, so the fit was calculated using all pressures.
Smoothed offsets were determined using a 1st-order fit for all
the stations.  The resulting smoothed offsets were then applied
to the data.  Most offsets were then manually adjusted to account
for discontinuous shifts in the conductivity transducer response,
and to insure a consistent deep Theta-S relationship from station
to station, particularly within individual basins.  Station 9,
cast 4 was the only cast which showed any discontinuity with
surrounding stations in the conductivity transducer response, and
it was adjusted to match its own bottle salinities, which also
matched the deep Theta-S data to its surrounding basin stations.

     The reason so many casts had to have additional manual
adjustment of the conductivity offsets is related to the
difficulties in calculating time-series data averages for the
water samples collected.  Even after using a "settle time" of 3
seconds, there remained a general positive bias for the bottle-
minus-CTD differences:  the averaged CTD conductivity was still
slightly higher than it should have been by .0010 to .0030
mmho/cm.  There did not seem to be a bias in the averaged CTD
temperature.  Since the bottle-minus-CTD conductivity differences
were low, the calculated correction offsets were too high; most
manual adjustments to the conductivity offsets were in the range
of -.0015.
          *     *     *     Revision     *     *     *

     Due to a change in the temperature correction applied to the
data, the conductivity corrections were also offset in August
1998 so that the salinities remained essentially unchanged from
the August 1992 data release.
       *     *     *     *     *      *     *     *     *

3.2.3.3.  Bottle vs. CTD Conductivity Statistical Summary

     The ODEN-91 calibrated bottle-minus-CTD conductivity differ-
ences  yield  the following statistical results: (NOTE that these
include bottle salts which are known to have problems.)


cruise  |    pressure     | mean conductivity diff'ce | standard  | #values
        |  range(dbars)   |   (bottle-CTD mmho/cm)    | deviation | in mean
--------+-----------------+---------------------------+-----------+--------
ODEN-91 | all pressures   |           .00085          |  .01332   |  1185  
        | allp (4,2rej) * |           .00069          |  .00204   |  1130  
        | press > 950     |           .00058          |  .00174   |   649  
        | p>950 (4,2rej)* |           .00057          |  .00096   |   611  
--------+-----------------+---------------------------+-----------+--------
  * "4,2rej" means a 4,2 standard-deviation rejection filter was applied to
     the differences before generating the results.


3.3.  CTD Dissolved Oxygen Data

     Dissolved oxygen data were acquired using a Sensormedics
dissolved oxygen sensor.  There were numerous technical
difficulties with the CTD oxygen sensor.  For the majority of
downcasts, the signal was bad for the top 200 decibars or so,
after which it would steady out and seem to act in a normal
fashion.  The upcast CTD oxygen is unacceptable due to signal
distortion following the CTD power-down at trips.  In addition,
the extreme cold conditions encountered in this part of the world
oceans cause difficulties in processing CTD oxygen data.  Current
software cannot correct these problems and no CTD oxygen data are
reported for the cruise.


3.4.  Additional Processing

     Some casts encountered transient signal glitches resulting
in conductivity or pressure drop-outs.  A software filter was
used to remove/correct these.  After filtering, the downcast
portion of each time-series was pressure-sequenced into 2-decibar
pressure intervals.  A ship-roll filter was applied to each cast
to disallow pressure reversals.  Problems in the data set have
been documented below and in the CTD Processing Comments table
below.



4.  General Comments/Problems

     There were 52 STS/ODF CTD rosette casts.  In addition there
were 37 Swedish CTD rosette casts (usually to about 1000
decibars).  Besides collecting Acoustic Doppler Current Profiler
(ADCP) data, these casts were used to increase the resolution of
the water column at each station by increasing the number of
discrete samples.  No CTD data is reported for them on this tape.
There is one pressure-sequenced CTD data set for each of the 52
STS/ODF CTD casts.  The data reported is all from downcasts, and
all casts except for Station 8, cast 4, were to near the ocean
floor.

     Freezing of the CTD sensors or extreme cold caused problems
at the start of most casts.  Shortly after entering the water,
the package was yo-yoed until the temperature and conductivity
sensors appeared to be stable; then the cast was continued.  For
the last eight casts, we brought the package back up out of the
water in an attempt to get a clean start to the cast.  Most of
the casts had surface levels extrapolated (up to the top 6
decibars) using a quadratic fit through the next three deeper
levels.  Recorded surface values were rejected only when it
appeared that the drift was caused by sensors adjusting to the
in-water transition or freezing.  Extrapolated surface levels are
documented in the CTD Processing Comments table below.

     It should be kept in mind that the ship usually had the bow
thrusters flushing during CTD casts to maintain ice-free
conditions for the CTD wire.

     There were severe winch and wire problems throughout the
cruise.  These resulted in numerous stops, pauses or yoyos during
casts.  Luckily, these usually occurred during the upcasts.




          Arctic Ocean Expedition 1991 (ODEN-91) CTD Processing Comments



     station   5 cast  1:   0,2-db levels extrapolated; CTD #6 cast
     station   8 cast  4:   0,2,4-db levels extrapolated; test cast for CTD #4 to 390 db
     station   9 cast  4:   0,2,4-db levels extrapolated
     station  10 cast  2:   0,2,4-db levels extrapolated
     station  11 cast  2:   0,2,4-db levels extrapolated
     station  13 cast  2:   approx. -.0019 psu salinity offset from 1498 db to cast end
     station  14 cast  3:   0-db level extrapolated
     station  17 cast  2:   0,2-db levels extrapolated
     station  19 cast  2:   0,2-db levels extrapolated
     station  20 cast  3:   0,2,4-db levels extrapolated
     station  21 cast  3:   0,2-db levels extrapolated
     station  22 cast  2:   0,2-db levels extrapolated
     station  23 cast  2:   0-db level extrapolated
     station  24 cast  1:   0-db level extrapolated
     station  25 cast  3:   0,2-db levels extrapolated
     station  26 cast  2:   0,2,4,6-db levels extrapolated
     station  27 cast  3:   0,2-db levels extrapolated
     station  28 cast  2:   0-db level extrapolated
     station  29 cast  3:   0-db level extrapolated
     station  30 cast  2:   0-db level extrapolated
     station  31 cast  2:   0,2,4-db levels extrapolated
     station  32 cast  2:   0,2,4-db levels extrapolated
     station  33 cast  2:   0,2,4-db levels extrapolated
     station  34 cast  2:   0,2,4-db levels extrapolated
     station  35 cast  2:   0,2,4-db levels extrapolated
     station  36 cast  2:   0,2-db levels extrapolated
     station  37 cast  2:   0,2-db levels extrapolated
     station  38 cast  2:   0,2-db levels extrapolated
     station  39 cast  2:   0,2-db levels extrapolated
     station  40 cast  2:   0,2,4-db levels extrapolated
     station  41 cast  2:   0,2-db levels extrapolated
     station  43 cast  2:   0,2,4-db levels extrapolated
     station  44 cast  3:   0,2-db levels extrapolated
     station  45 cast  2:   0,2,4-db levels extrapolated
     station  46 cast  3:   0-db level extrapolated
     station  47 cast  2:   0-db level extrapolated
     station  48 cast  1:   0-db level extrapolated
     station  50 cast  2:   0,2-db levels extrapolated
     station  51 cast  2:   0,2,4,6-db levels extrapolated
     station  52 cast  2:   0,2-db levels extrapolated
     station  54 cast  2:   0-db level extrapolated
     station  58 cast  2:   0,2,4-db levels extrapolated; top 50 db 
                            questionable:  temp sensor not responding 
                            properly 24-50 db
     station  59 cast  2:   0-db level extrapolated



DATA PROCESSING NOTES

2007-06-11  Key         BTLNBR    Submitted       Corrected longitudes
            Thanks for the corrections. I've updated my files accordingly. The updated 
            datafile and README are attached (with the final EXPOCODE). This cruise was 
            part of the Jan. 07 CARINA distribution. - Key

            ODF did the CTD data this cruise and our longitude for station 19 cast 2 is 
            118 deg 29.8 min E and station 20 cast 3 longitude is 127 11.2 E. ODEN 
            departed Goteborg, Sweden, July 26, 1991. Our date for station 4 is 8/17/1991 
            not 7/17/1991. - Muus 

2009-07-16  Muus        BTL       Website Update   BTL data online
            Notes on ODEN_1991 bottle data. EXPOCODE 77DN19910726 July 7,
            2009 D. Muus

            1. Data file is an exact copy of CARINA: ODEN/
               77DN9107/77DN19910726_hy1.csv received from Bob Key Jan 26, 2009;
               Java Ocean Atlas was used to check the data.
            2. DELO18 is used in place of O18O16. CCHDO parameter mnemonic changed
               to DELO18 to reflect its more accurate description of the values given.
            3. SAMPNO equals BIONBR.
            4. CTDSAL not included. Reason unknown.
            5. DOC has some unusually high values that are flagged 2.
               e.g Sta 48, Ca 1, Btl#s 24-21 17.9,499-601db
               Sta 55 Ca 1, Btl#s 21-24 799-957db
               Sta 12 Ca 3 Btl#22 2499.8db is high with flag 3 so someone did
               check quality. 
            
