UNIVERSITY OF WASHINGTON CTD/GTD DATA FOR HALE-ALOHA 1, 2 AND 3
		12 JAN 1997 to 13 MAY 1998


   During the period of 12 January 1997 through 13 May 1998, Steven
   Emerson and Charles Stump of the University of Washington deployed a
   CTD/GTD device at the HALE-ALOHA mooring site of the University of
   Hawaii. This was done in association with Dave Karl and Terry Houlihan
   of UH. This CTD/GTD device was placed at 50 m depth in each mooring
   cycle. The device consists of a Seabird Seacat 16DO CTD capable of
   measuring temperature, salinity, pressure and oxygen. Attached to
   this CTD is a gas tension device (GTD) designed and built by Dr.
   Bruce Johnson at Dalhousie University in Halifax, Nova Scotia,
   Canada. The GTD device measures total gas pressure across a silicone
   membrane. A pinhole opening below the membrane is connected to a
   Parascientific pressure sensor. Changes in partial pressure alter
   the sensor frequency. These frequency changes, as well as
   temperature, salinity, pressure and oxygen are stored in the
   Seacat's memory until recovery. Upon recovery, the data is
   downloaded, processed and converted to scientific units using the
   calibration values of the Seabird CTD and the GTD.  The CTD/GTD data
   is reported out in the following units:


		temperature  -  Deg C
		salinity     -  o/oo
		Sigma t      -  kg/m3  (calculated)
		pressure     -  mbars
		oxygen       -  umol/l
		GTD          -  mbars


    During the course of each mooring, samples were taken at Station 8
    near the HALE-ALOHA mooring site to calibrate the CTD/GTD. These
    samples were taken at the time of deployment and several times
    during the course of each mooring cycle. Samples were obtained
    using the University of Hawaii rosette and CTD. The bottles were
    sampled for oxygen determined by Winkler titration and O2/Ar, O2/N2
    and N2/Ar ratios determined by mass spectrometry.  CTD values from
    these casts were used to confirm the temperature and salinity data
    from the UW CTD. The Winkler oxygen results were used to calibrate
    the oxygen values registered by the UW CTD. The ratios obtained by
    mass spectrometry were used to calculate concentrations of N2 and
    Ar based on the Winkler O2.

    The concentration of N2 is calculated from the measured
    concentration of O2, [O2], and the total gas pressure, P, assuming
    the partial pressures of argon, pAr, and water, pH2O, are at
    saturation equilibrium and that the atmospheric pCO2 is
    negligible.

	[N2]  =  { Sigma P - [O2] / SO2 - (XAr  +  XH2O) Patm} SN2 ;

    where S is the solubility which is a function of temperature; X is the
    mole fraction of the gas in the atmosphere and Patm is the
    atmospheric pressure. The latter value was obtained from NODC Buoy
    51001 for the calculation. This calculated N2 concentration is then
    compared to the samples obtained from Station 8.