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SUMMARY:Measuring pH variability using an experimental sensor on an underw
 ater glider - Michael Hemming\, University of East Anglia/LOCEAN\, UPMC\, 
 Paris
DTSTART:20170926T100000Z
DTEND:20170926T110000Z
UID:TALK74381@talks.cam.ac.uk
CONTACT:Dr Peter Davis
DESCRIPTION:Autonomous underwater gliders offer the capability of measurin
 g oceanic parameters continuously at high resolution\, on timescales that 
 can extend to many months. An experimental ion-sensitive field-effect tran
 sistor (ISFET) sensor measuring pH was attached to a glider during the REP
 14-MED experiment in June 2014 in the Sardinian Sea. Water samples were co
 llected from a nearby ship and analysed for DIC and AT to derive pH for va
 lidating the ISFET sensor measurements. The vertical resolution of the pH 
 sensor was good (1 to 2 m)\, but stability was poor and the sensor drift
 ed in a non-monotonous fashion. Corrections were applied to sensor measure
 ments to account for drift\, and temperature and pressure effects. Further
 more\, Sunlight caused an apparent sensor pH decrease of up to 0.1 in surf
 ace waters around local noon\, highlighting the importance of shielding th
 e sensor from light in future deployments. The corrected pH from the ISFET
  sensor is presented along with other parameters measured by the glider\, 
 providing insights into the physical and biogeochemical variability in the
  Sardinian Sea. 
LOCATION:British Antarctic Survey\, Innovation Centre\, Seminar Room 2
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