FRANKLIN CRUISES FR 8/90, 5/92 AND 8/93
DATA DOCUMENTATION
JGOFS WESTERN EQUATORIAL PACIFIC PROCESS STUDY

[1] General:

Parameter:			Surface pCO2
Level 1:			<Yes > 
Principal Investigator:	Denis Mackey 
Institute Address:		CSIRO Division of Marine Research
E-Mail Address:		Denis.Mackey@marine.csiro.au

List of Parameters:	pCO2
List of Units:			atm

[2] Sampling:

Gear (e.g. CTD, pump, etc.):	Oceandata Thermosalinograph. 
Standard Depths:	Intake at 3 m
Chemicals used:			Hansson Buffers fof pH measurement
Special Procedures:	Water taken from thermosalinograph via a T-connection. Flow was controlled at 500 ml min-1 by a peristaltic pump. pH electrode output (mV) and seawater temperature were logged at 1 sec intervals and stored as 1 min averages
Comments and Notes:	Electrode calibrated daily against Hansson buffers which were made up every 1-2 days

3] Analysis:

Instrument:	Ross electrode (Orion 81-03SC), Radiometer PHM 85 pH meter with temperature probe T801. In-house flow cell fitted with a pulse dampener and Pt earth for seawater. 

Method:		Since the surface waters were always nutrient depleted, we calculated the alkalinity from the salinity and a specific alkalinity of 0.1194 (Skirrow in Chemical Oceanography, Riley and Skirrow editors, Academic Press, London, 1975). The pCO2 was then calculated from pH and alkalinity using the carbonic acid constants of Goyet and Poisson (Deep-Sea Research, 36, 1635-1654,1989), the boric acid constants of Hansson (Acta Chemica Scandanivica, 27, 924-939, 1973; Deep-Sea Research, 20, 461-478, 1973; Almgren et al., Deep-Sea Research, 22, 635-646, 1975) and the CO2 solubility data of Weiss (Marine Chemistry, 2, 203-215, 1974; Skirrow, In Chemical Oceanography, Riley and Skirrow editors, 1-192, 1975)

Precision:	estimated as 1 atm, accuracy estimated as 8 atm
Comments:	pCO2 was calculated from 5 minute averages of the pH

[4] Results:

Quality of Data:	On FR05/92, the difference between pCO2 calculated from the pH and direct measurements had an RMS difference of  8 atm. 
Known Problems:	

 [5] Brief description of analytical method 
Mackey, D. J., Higgins, H. W., Mackey, M. D. and Holdsworth, D. (1998) Algal class abundances in the western equatorial Pacific: estimation from HPLC measurements of chloroplast pigments using CHEMTAX. Deep-Sea Research, 45, 1441-1468.

Mackey, D. J., Parslow, J. S., Griffiths, F. B., Higgins, H. W. and Tilbrook, B. (1997) Phytoplankton productivity and the carbon cycle in the western equatorial Pacific under ENSO and non-ENSO conditions. Deep-Sea Research, 44, 1951-1978.

[6] Comments: