Haruphone/Tsunami 2000 Leg 1 Readme File

Ship:			NOAA research vessel Ronald H. Brown
Cruise Start:		Seattle, WA, May 22, 2000
Cruise End:		Seattle, WA, June 4, 2000
Chief Scientist:	Matt Fowler, Lt. Keith Roberts
System Operator:	Jonathan Shannahoff
Expocode:               33RO20000522

Method:
Infrared absorption of dried gas.  For details of the system see: 
Measurement of fugacity of Carbon Dioxide in surface water and air using 
continuous sampling methods.  Wanninkhof and Thoning, 1993 in Marine Chemistry
44, 189-205, 
And:
Feely, R.A., R. Wanninkhof, H.B. Milburn, C.E. Cosca, M. Stapp, and P.P. Murphy, 
A new automated underway system for making high precision pCO2 measurements 
onboard research ships, Analytica Chim. Acta, 377, 185-191, 1998.

The three standard gases come from CMDL in Boulder and are directly traceable to 
the WMO scale.

Sampling Cycle:
The system runs on an hourly cycle during which 3 standard gases, 3 air 
samples from the bow tower and 8 surface water samples (from the 
equilibrator head space) are analyzed on the following schedule:

Mins. after hour		Sample
4				Low Standard
8				Mid Standard
12				High Standard
16.5				Water
21				Water
25.5				Water
30				Water
34				Air
38				Air
42				Air
46.5				Water
51				Water
55.5				Water
60				Water

Units:
All xCO2 values are reported in parts per million (ppm) and fCO2 values 
are reported in microatmospheres (uatm) assuming 100 % humidity at the 
equilibrator temperature.

Notes:

1. The ship encountered a strong CO2 sink as it paralleled the coast of
Kodiak Island, with water xCO2 values dropping to 150 PPM.  Also, when
approaching Seattle on the return leg water values in the range of 175
to 750 PPM were observed.  Since these values are well outside the range
of the standard gases (281.16, 356.99, & 420.47) they should be considered
to be rough estimates only.
2.A high cyclical variation in air xCO2 values caused me to suspect a
leak.  I therefore replaced all air xCO2 values with 376.00, which I
derived from climatology records provided by CMDL in Boulder.  I used 
values from Cold Harbor, Alaska and Cape Meares, Oregon from 1993 to 1997.
For each year I averaged all values in the period from late May to early 
June and plotted them by year.  I used a linear fit to extrapolate each
station's values to the year 2000 to arrive at the value of 376.00.  This
matches fairly closely with minimum air xCO2 values observed during the
cruise which fell in the range of 374.50 to 377.00.

For questions or comments contact:
Bob Castle
4301 Rickenbacker Causeway
Miami, FL 33149
305-361-4418
castle@aoml.noaa.gov