RB-07-09
Stratus 2007 Readme File

Ship:			NOAA research vessel Ronald H. Brown
Cruise Start:	        Rodman, Panama, Oct. 16, 2007
Cruise End:		Galapagos Islands, Nov. 7, 2008
Chief Scientist:	Bob Weller
System Operator:	Dana Mancinelli
Expocode:               33RO20071016

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, & 514.29 ppm) 
should be considered approximate (within 5 ppm).  While individual data points
above 514 or below 289 may not be accurate, the general trends should be
indicative of the seawater chemistry.
2.	The salinity readings from the ship's TSG were inaccurate and were replaced 
with the salinity readings from the Seabird Micro TSG in the Hydro Lab sink.
3.	The system was down from Oct. 19 at 1816 through Oct. 23 at 1828 due to
a computer crash.  When it came back on, water flow was intermittent for about
5 hours and many water values in this time period have been removed.
4.	The ancillary data from the ship's computer system ends on Nov. 6 at 0010,
30 hours before the end of the cruise.  Since this data includes the barometric
pressure which is used to compute fCO2Air, the missing values have been replaced
with EqP + 0.8, where EqP is the pressure recorded by the Setra barometer in 
the Hydro Lab.  The equation is based on the difference in readings prior to the
end of the ship's data.


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