Internal ice stress

Instrument: Geokon vibrating wire stress sensor.
Uncertainty: 15%, 20 kPa resolution; Direction: 2.5 degrees; 
Instrument temperature sensitivity: 5kPa/C
File format: All files are ASCII comma separated variable format. 
There is a directory STRESS. The filename convention is STRXXX where
XXX denotes the site. MIL is Milford, WIL is Wilmington,DOV is Dover, 
DEL is Delaware, RM9 is remote site 9, and BAL is Baltimore 
Contacts: jrichtermenge@crrel.usace.army.mil 



The stress and deformation array covered 100 km region, centered 
on Ice Station SHEBA. It was installed at the start of the field 
program, in October 1997. Stresses were measured using gauges 
designed specifically for this application. The gauge is a stiff, 
thick-walled steel annulus, which houses a vibrating wire assembly. 
Changes in the frequency of vibration of the wire define the stress 
being applied to the annulus. The stress sensor is frozen into the 
ice cover by drilling a hole through the ice. The stress sensors 
were located within the interior of the stress and deformation array, 
at 10 different sites. Seven of these sites were placed approximately 
0.5 km apart, along the boundary of the SHEBA floe. The remaining 3 
were installed on separate floes that were located about 15 km from 
the main floe. Measurements from each sensor describe the time series 
of ice stress at a single point in the ice cover.


Stress file descriptors:

Baltimore
	Lead:  Stress sensor installed in 36-cm-thick lead ice, at a 
               depth of 21 cm.  This refrozen lead was adjacent to SHEBA 
               home floe.  Time series begins 10/31/97, ends 7/9/98.  
               Also located at this site was a thermistor string, thickness 
               gauges, and a PAM site.
	Multiyear floe Top:  Stress sensor was installed in 136-cm-thick 
               multiyear ice, at a depth of 28 cm.  This site was near the 
               edge of the SHEBA home floe.  Time series begins 10/31/97, 
               ends 7/9/98.  Also located near this site were thickness gauges.
        Bottom:  Stress sensor was installed in 136-cm-thick multiyear ice, at a depth 
         of 109 cm.  This site was near the edge of the SHEBA home floe.  
         Time series begins 10/31/97, ends 9/15/98. Also located near this site were thickness gauges.


Wilmington:  Stress sensor was installed in 104-cm-thick multiyear ice, at a depth of 35.3 cm.  
         This site was near the edge of the SHEBA home floe.  Times series begins 10/31/97, ends 5/1/98.

Dover:  Stress sensor was installed in 156-cm-thick multiyear ice, at a depth of 50.5 cm.  
         This site was near the edge of the SHEBA home floe.  Time series begins 10/14/87, ends 5/17/98.

Milford:Top: Stress sensor was installed in 93-cm-thick multiyear ice, at a depth of 24.0 cm.  
             This site was neat the edge of the SHEBA home floe.  Time series begins 10/14/97, ends 5/17/98.
	Bottom: Stress sensor was installed in 108-cm-thick multiyear ice, at a depth of 100 cm.  
             This site was near the edge of the SHEBA home floe. Time series begins 10/14/97, ends 5/17/98.

Rehoboth: Stress sensor was installed in 148-cm-thick multiyear ice, at a depth of 46 cm.  
        This site was near the edge of the SHEBA home floe.  Time series begins 10/11/97, ends 5/17/98.

Delaware:Top:  Stress sensor was installed in 160-cm-thick multiyear ice, at a depth of 39.5 cm.  
              This site was in the center of the SHEBA home floe. Time series begins 10/14/97, ends 6/6/98.
	Bottom 1:  Stress sensor was installed in 160-cm-thicm multiyear ice, at a depth of 99 cm.  
              This site was in the center of the SHEBA home floe.  Time series begins 10/14/97, ends 6/6/98.
	Bottom 2:  Stress sensor was installed in 160-cm-thicm multiyear ice, at a depth of 98 cm.  
              This site was in the center of the SHEBA home floe.  Time series begins 10/14/97, ends 6/6/98.

Remote Site 9:  Stress sensor was installed in 116-cm-thick multiyear ice, at a depth of 44.5 cm.  
       This site was in the center of a floe, approximately 15 km from the SHEBA home floe.  
       Time series begins 10/2/87, ends 7/24/98.  Also located at this site was a position buoy and 
       salinity/temperature ocean profiler.

Remote Site 11:  Stress sensor was installed in 126-cm-thick multiyear ice, at a depth of 44.5 cm.  
       This site was in the center of a floe, approximately 15 km from the SHEBA home floe.  
       Time series begins 10/6/87, ends 7/25/98.  Also located at this site was a position buoy and 
       salinity/temperature ocean profiler.