                Additional information to the
          Brief descriptions of the physical and chemical data
                 (Marine Hydrophysical Institute)

                        A. Physical data

                    1. Measured parameters.

     Depth (H) of the measurement,  temperature (T) and salinity
(S)  were  obtained  with   Nansen   Bottles,  and  CTD-systems.

                           2. Units.

     2.1. Temperature - Celcium degrees, Salinity - practical
salinity units (PSU), Depth - meters.
     2.2. These   temperature   scales   were   used  during  the
measurements:
  from  1948  to  1970  year  -  IPTS-1948;
  from  1970  to  1990  year  -  IPTS-1968.
And next salinity scales were used:
  before 1969 year - Knudsen's  scale  with  salinity  calculated
from chlorine measurement (Cl, promille).
               Sk = 1,805 Cl + 0,03  (promille);        (1)

  from 1970 to 1982 year - R.Cox's salinity  scale  (1969)   with
salinity calculated from relative conductivity R15:

    S = -0.08996 + 28.29720*(R15) + 12.80832*(R15)^2 -
    - 10.67869*(R15)^3 +  5.98624*(R15)^4 - 1.32311*(R15)^5   (2)

                    3. Methods and devices

     3.1. The standard hydrological methods were used to  produce
the hydrological data:
 - Nansen Bottles with deep-sea reversing thermometers;
 - CTD-sounding systems.
     3.2. For salinity determination before 1969 the argenometric
titration from the chlorine was  used  with  salinity  calculated
from  Knudsen's formula (1).  The finish of reaction was obtained
from visual observation of the indicator color change.  Errors of
estimation  of the chlorine observations on aboard condition were
no more than +-0.015 promille,  and from salinity - no more  than
0.025 promille with confidential probability 0.95.
     From 1969  year  salinity  was  determined   by   means   of
laboratory  electrical  salinity-meter  GM-65  and  it  was  also
calculated from formula (2).  Error of estimation of the salinity
in  water  sample was no more +-0.02 promille  with  confidential
probability 0.95.
     3.3. Temperature observation during  batometric  casts  was
provided by means of Deep-sea reversing thermometers - DSRT.
     Root mean  deviation   of  the  temperature  observation was
0.015 degrees.  Total temperature observation  error  was  +-0.04
degrees with confidential probability 0.95.
     3.4. Depth observation during batometric casts was  provided
by  means  of DSRT.  Root mean deviation of the depth observation
was 3-5 meters from 0 to 1000 meters depth and 0.5 percents  from
over 1000 meters depth.
     3.5. CTD-sounding  systems  were   used   for   temperature,
salinity  and  depth  observations  from  0 to 2000 meters depth.
Device  types  are  ISTOK-3,  ISTOK-4,   and   ISTOK-5.   General
characteristics of those are in table 1.

                                                        Table 1.
_________________________________________________________________
    Parameters          :    ISTOK - 3;     :      ISTOK - 5
                        :    ISTOK - 4      :
_________________________________________________________________
1. Pressure, dBar
  - Range                     0 - 2000            0 - 6000
  - Sensibility               0.5                 0.5
  - error, %, at confidential
    probability a=0.95        0.25                0.25
 2. Temperature, Deg.C
  - Range                   -2...+35             -2...+35
  - Sensibility               0.01                0.0025
  - Static error at
    confidential probability
    a=0.95                    +-0.03             +- 0.025
  - Temperature sensor
    inertia, sec            0.4 - 1.0           0.2 - 0.4
3. Relative conductivity
  - Range                     0 - 1.6             0 - 1.5
  - Sensitivity               0.0004              0.00006
  - Error at confidential
    probability a=0.95       +-0.001             +-0.0007
4. Salinity, UPS
   (calculated value)
  - Range                     0 - 40              0 - 40
  - Sensitivity               0.018               0.003
  - Static error at
    confidential probability
    a= 0.95                 no more 0.04       no more 0.03
5. Sampling Frequency, Hz         0.7                 4
_________________________________________________________________

               4. Expert's estimations criteria

    4.1. Temperature and salinity profiles were  subject  of  the
expert's estimation.
    Main criteria used:
     - static vertical  stability  of  the  water   mass:
     - excess of the dinamical  error  of  salinity  measurements
over the  predefined  level (the dynamical error is the error due
to the different inertia of the salinity and temperature sensors).
     The static   stability  was  determined  using  additionally
calculated density anomaly Astp. If the difference between values
Astp(i+1)-Astp(i) is  negative and absolute value of it is > 0,02
kg/m^3, then quality flag "4" was introduced for the (i+1)  value
( (i+1) value corresponds to the bigger depth).
     The same quality flag was introduced if one  or more  values
differed from  upper  and  lower  values  more  than  0,02 kg/m^3
(positive spikes).

**   All values  with  quality  flag  "4" are wrong and cannot be
**   used!

     If the negative difference of the adjacent values was in the
range (0.02  ....  0.01)  kg/m^3  then  quality  flag   "3"   was
introduced. It  can  be natural variability or instrumental error
of the CTD-probe.

    Negative density  differences  with  value  below  0.010-0.007
kg/m^3 didn't mark for ISTOK-3 CTD-probe system.
    Negative density  difference  with   value  below  0.007-0.004
kg/m^3 didn't mark for ISTOK-5 CTD-sounding system.

    Values were   marked   also  with  quality  flag  "3",  where
dynamical error of salinity measurement could be more than +-0.04
PSU  without  density  inversions.  These marks,  in general, are
in seasonal and main thermocline.

    Data with quality flag "3" can be used depending on  the user
tasks.

 Experts: V.I.Zaburdaev, A.F.Ivanov



                   B. Optical sounding device

            Logarithmic Photometer-Transparency Meter

     Logarithmic Photometer-Transparency   Meter    (LFP)     was
developed  at  the  Laboratory  of Optical Oceanography of Marine
Hydrophysical Institute,  Sevastopol. This instrument is used for
measuring   the   attenuation   coefficient   of  directed  light
(transparency) of seawater within narrow diapasons of visible and
near  ultraviolet  regions  of  the  spectrum.  With  the  aim of
reducing systematic errors of measurement due  to  the  secondary
dispersion of light in water, the optical circuit "lens pin hole"
is used,  which permits the angle of vision of the receiver to be
brought up to 15-30 min.
     The seawater   attenuation  meter  is  designed  for  taking
profile of optical properties of ocean water.  The output of  the
meter   is   analogous   signal   proportional  to  the  seawater
attenuation  coefficient.   The   instrument   is   designed   as
double-beam photometer with the single photo-receiver alternately
irradiated with a measuring and  a  reference  light  beams.  The
photometer  allows  to  record  vertical  profiles of attenuation
coefficient c(z) in  eight  narrow  intervals  in  visible  range
dependent on depth.

Absolute  values  of  the  attenuation  coefficient are given in 
1/meter at the decimal logarithm base.

                        SPECIFICATIONS

     1. Range of measured attenuation,     1/m      0.01 - 1.0
     2. Used wavelength,                   mkm     0.36 - 0.65
     3. Spectral bandwidth,                mkm            0.01
     4. Error,                             1/m            0.01
     5. Instrument optical base,           m                 2
     6. Field-of-vision angle of
        photoreceiver, angular             min              30
     7. Depth of submergence,              m              1000
     8. Power consumption,                 w                15
     9. Weight,                            kg               45



                     C. Hydrochemical data 

     Hydrochemical information of R/V "Mikchail Lomonosov" and R/V
"Academician   Vernadsky"   of   Marine  Hydrophysical  institute,
received in the Indian ocean from 1966 to  1981  (9  cruises),  is
presented  in  this  data  set.  In   general, hydrochemical  data
include information on dissolved oxygen (O2), inorganic phosphates
(PO4), silicates  (Si), nitrates (NO3), nitrites (NO2),  pH values
(pHv),  and total alkalinity

     Verification of data sets on PC computer  has  been  done  to
receive the answers for two questions:
     - Are there any misprints?  (Misprints  have  been  corrected
immediately);
     - Are   there   any   disagreement   between   the   vertical
distribution  of  parameters  on individual oceanographic stations
and  our  understandings  of   processes   responsible   for   the
hydrochemical structure? (As result of this work some data in data
sets have been noted as not very reliable).
     In general, the amount of data, noted as not reliable, is low
(2 - 5 points for individual hydrochemical  parameters  for  every
cruise).  The  highest amount of such "not reliable" data has been
revealed for the 11-th cruise of R/V  "Akademik Vernadsky" (about
20 points).
     Different methods   were   used   to   determine   the   same
hydrochemical  parameter  in  different  cruises  and it should be
recognized to analyze and compare information of this general data
set correctly.
     The next methods were used:
     1. Dissolved   oxygen  was  determined  by  Winkler's  method
according  to  guidance  [1].  Since  the  1978  modification   of
Winkler's method [2] has been used.
     2. The method of Denige and Atkins (with SnCl2 as  a  reducer
of  phosphomolibdate  complex)  was  used  since  1966  to 1975 (4
cruises) to determine inorganic  phosphates  [1].  Since  1979  (5
cruises) the method of Murphy and Riley [2] (with ascorbic acid as
reducer) has been using.
     3. The  method  of  Mullin  and  Riley  (with methol-salphite
solution as reducer of silicomolibdic acid) was used since 1966 to
1980  (7  cruises)  [1].  In  22-nd  and  24-th cruises of the R/V
"Akademik Vernadsky" (1980  and  1981)  modification  of  above
mentioned method was applied (with ascorbic acid as reducer) [2].
     4. The method of Morris and Riley with reducing  of  nitrates
with copper-coated cadmium grains in glass burette was used in all
cruises.
     5. The   method  of  Griess-Ilosvay  was  used  to  determine
nitrites [1,2].
     6. pHv  value  was  determined  by visual comparison with the
Serensen scale in the 19-th cruise of  R/V  "Mikchail  Lomonosov".
The reproducibility is+-0.1 [1].
     In the other cruises pH-meters  "pH-262"  and  "pH-340"  were
used to determine pH value. The reproducibility is+-0.05 [2].
     7. Total alkalinity was determined by  volumetric  method  of
Bruevich  (titration of sample of water with hydrochloric acid and
flushing it with CO2-free air).  The end point  of  titration  was
controlled visually. The reproducibility is+-0.005 mM/l [1,2].

     FEK-m, FEK,  or  FEK-56  (the type of photometer) was used to
measure the absorbency of all color solutions.

     Units:
     O2  - milliliters/liter
     Alk - millimoles/liter
     Other parameters - micromoles/liter

                            Literature
     1. "Guidance   on   the  routine  hydrochemical  methods  for
oceanographic  investigations  in  the  International  Geophysical
Year", IO RAS (edited by S.V.Bruevich), 1957.
     2. "Methods  on  the  hydrochemical  investigations  of   the
ocean", Moscow, Nauka, 1978.


