RB-07-04
Ocean Exploration Readme File

Ship:			NOAA research vessel Ronald H. Brown
Cruise Start:	        Ft. Lauderdale, FL, June 4, 2007
Cruise End:		Galveston, TX, July 6, 2007
Chief Scientist:	Charles Fisher
System Operator:	Randy Ramey
Expocode:               33RO20070604

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.	Any values outside the range of the standards (289.06, 370.90, & 411.42 ppm) 
should be considered approximate (within 5 ppm).  While individual data points above 
411 or below 289 may not be accurate, the general trends should be indicative of the
seawater chemistry.
2.	Gas flow through the equilibrator dropped to zero on June 8 at 0740 and never
recovered.  All sea surface values after this time have been removed.  Air values
were not affected.
3.	SST and salinity values from the ship's TSG were bad in several spots.  Since
these are used for computing fCO2 and occurred after the flow stopped in the water 
phase, no attempt has been made to correct them.
4.	Some atmospheric values above the normal open-ocean value (~ 383 ppm) have been
retained.  There is no indication of stack gas contamination or instrument malfunction
and as the ship was near land, it is assumed that these high values were cause by 
land-based sources.


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