RB-06-02
Western Boundary Time Series Cruise Readme File

Ship:			NOAA research vessel Ronald H. Brown
Cruise Start:	      	Bridgetown, Barbados, March 12, 2006
Cruise End:		Charleston, S.C., March 28, 2006
Chief Scientist:	Molly Baringer
System Operator:	Jonathan Shannahoff
Expocode:               33RO20060312

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 (303.23, 370.90, & 411.42 ppm) 
should be considered approximate (within 5 ppm).  While individual data points above 
411 or below 303 may not be accurate, the general trends should be indicative of the
seawater chemistry.
2.    The salinity reading from the ship's TSG was bad from the beginning of the cruise
until March 17 at 2049.  It was replaced with values based on the Seabird TSG near the
underway system (Seabird salinity - 0.106).
3.	From March 16 at 1523 to March 17 at 0107 a spike occurred in the water xCO2
values.  While the cause of this spike could not be exactly determined, the values were
removed because it was suspected that they were not correct.
4.	There were 4 approximately one day long periods where the Licor cell temperature
was very noisy.  Since the cell temperature is not used in calculating xCO2, the values
were not removed, but it could be indicative of problems developing with the Licor.
  

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