Arctic Ocean ARGOS Salinity Buoys  1985 - 1994


James Morison, Principal Investigator  (morison@apl.washington.edu)
Roger Andersen   (roger@apl.washington.edu)
Polar Science Center
Applied Physics Laboratory
University of Washington
1013 NE 40th
Seattle, WA  98105-6698   USA
Telephone  (206) 543-6613
FAX  (206) 543-3521


Between 1985 and 1994, the Polar Science Center at the University of Washington deployed
24 ARGOS data buoys in ice floes on the Arctic Ocean, from which six temperature and
conductivity sensor pairs were suspended as deep as 300 meters to allow calculation
of salinity and density.  Each sensor was sampled into a circular buffer every 12 minutes;
one sample was transmitted every minute and the polar region coverage by ARGOS satellites
provided sufficient redundancy to ensure that nearly every data point would get through.
Subjected to all the stresses and strains of Arctic pack ice, these buoys varied greatly
in their longevity, but the result is a substantial hydrographic record of the Arctic Ocean
for a decade.

The data is available here in an ASCII file of the original 12-minute samples.  An ARGOS
position fix is calculated once for each satellite pass, so latitude and longitude are
interpolated to the time of each sample.  Only some sensor levels, always including the
bottom, were provided with pressure sensors to directly measure the depth.  Depths of
intervening layers were calculated from a catenary model of the cable hanging beneath the
buoy hull

Each "hydrofile", for example Hydro.12795.1093, contains one month of data.  In this example
the file contains the complete set from the buoy with ARGOS ID number 12795 during October
1993.  Here is the first sample of this file:

      1993    296.917     75.363    216.855   1011.520    -22.800   12795
      9.7993    -1.5480    22.8280    28.2796    22.7169
     40.3643    -1.2590    24.3740    30.0738    24.1678
     70.6376    -1.0690    25.8770    31.8952    25.6394
    121.2271    -1.4070    26.1710    32.6299    26.2447
    203.4886    -1.4890    26.6340    33.3065    26.7962
                                                                                              11,1          Top
Each sample block consists of 1 header line and six depth-level lines samples at its 12-minute
sample time.  In the sample listed above, the header line is

      1993    296.917     75.363    216.855   1011.520    -22.800   12795

1993               is the year
296.917            is the day and fraction of day of this year, 1.000 = 1 January at 0000 GMT
75.363             (degrees North)  Latitude
216.855            (degrees East of Greenwich)  Longitude (degrees East of Greenwich)
1011.520           (millibars)  Atmospheric Pressure
-22.800            (degrees Celsius) Air Temperature
12795              is the ARGOS ID Number

The fifth depth level line (to choose a sample) in the first sample is

    203.4886    -1.4890    26.6340    33.3065    26.7962

203.4886            (meters)  Ocean Depth of this sensor level
-1.4890             (degrees Celsius)  Ocean Temperature at this level
26.6340             (Siemans/meter)  Conductivity
33.3065             (PSU)  Salinity
26.7962             (sigma-theta)  Density


In the not unusual case of an individual sensor failing while the remainder of the
buoy continued to function, the missing data point is flagged as -99.0000 for any variable.
An effort was made to edit out obviously erroneous samples.  However, idiosyncrasies of
ARGOS data transmission occasionally result in redundant samples for a particular time
that disagree.  Some such erroneous samples likely remain, and may be detected by an
unreasonable departure from the same sensor 12 minutes before and after.  Biofouling
was generally found to not be too serious in the Arctic, but is occasionally is an
issue for shallow sensor levels during the summer.  Buoy 12798 is a bizarre special case.
That buoy's bottom pressure sensor abruptly failed on 8 March 1994 (day 67) and abruptly
began reporting again on 26 May 1994 (day 146).  Since pressure at level 6 is critical for
calculating the depths of all sensor levels, the ocean sensors for this period are unavailable
for this period.  File Hydro.12798.9403 ends with the last pressure sample, file
Hydro.12798.9404 is missing completely, and Hydro.12798.9405 picks up when the depth sensor
wakes up.


Here is a bit larger sample from the start of Buoy 12795:

1993    296.917     75.363    216.855   1011.520    -22.800   12795
      9.7993    -1.5480    22.8280    28.2796    22.7169
     40.3643    -1.2590    24.3740    30.0738    24.1678
     70.6376    -1.0690    25.8770    31.8952    25.6394
    121.2271    -1.4070    26.1710    32.6299    26.2447
    203.4886    -1.4890    26.6340    33.3065    26.7962
    306.8454    -0.2650    28.6420    34.5883    27.7879
      1993    296.933     75.363    216.857   1011.760    -22.800   12795
      9.7993    -1.5480    22.8280    28.2796    22.7169
     40.3643    -1.2680    24.3650    30.0707    24.1655
     70.6376    -1.0830    25.8670    31.8965    25.6409
    121.2271    -1.3990    26.1770    32.6294    26.2440
    203.4886    -1.4870    26.6353    33.3061    26.7959
    306.8454    -0.2640    28.6420    34.5872    27.7870
      1993    296.942     75.363    216.858   1011.800    -23.200   12795
      9.7993    -1.5470    22.8920    28.3654    22.7866
     40.3643    -1.2660    24.3750    30.0822    24.1748
     70.6376    -1.1010    25.7990    31.8234    25.5822
    121.2271    -1.4040    26.1770    32.6349    26.2486
    203.4886    -1.4860    26.6360    33.3060    26.7957
    306.8454    -0.2643    28.6430    34.5889    27.7884
      1993    296.958     75.363    216.860   1011.920    -23.600   12795
      9.7939    -1.5490    22.8280    28.2805    22.7177
     40.3363    -1.2660    24.3600    30.0619    24.1583
     70.6201    -1.1110    25.8760    31.9385    25.6757
    121.2271    -1.4140    26.1650    32.6294    26.2444
    203.4886    -1.4870    26.6290    33.2974    26.7888
    306.8454    -0.2650    28.6420    34.5883    27.7879
      1993    296.975     75.363    216.862   1012.000    -25.200   12795
      9.7884    -1.5497    22.8280    28.2812    22.7183
     40.3079    -1.2700    24.3980    30.1174    24.2034
     70.5774    -1.1210    25.8640    31.9329    25.6714
    121.1604    -1.4270    26.1623    32.6399    26.2533
    203.4010    -1.4890    26.6317    33.3034    26.7937
    306.7316    -0.3250    28.6420    34.6565    27.8459
      1993    296.983     75.363    216.863   1012.080    -23.600   12795
      9.7857    -1.5500    22.8280    28.2815    22.7185
     40.2940    -1.2720    24.3430    30.0450    24.1447
     70.5563    -1.1260    25.8580    31.9301    25.6693
    121.1275    -1.4110    26.1610    32.6207    26.2372
    203.3578    -1.4900    26.6330    33.3064    26.7961
    306.6755    -0.2660    28.6420    34.5896    27.7890

 and so on...


End-of-ReadMe document


