RB-07-01
Western Boundary Time Series 2007 Readme File

Ship:			NOAA research vessel Ronald H. Brown
Cruise Start:	      	Charleston, SC, March 23, 2007
Cruise End:		San Juan, Puerto Rico, Apr. 10, 2007
Chief Scientist:	Molly Baringer
System Operator:	Jonathan Shannahoff
Expocode:               33RO20070323

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.	The water flow to the equilibrator was shut down on April 8 from
0446 to 1200.  All water values in this time period have been removed.
3.	The feeds from the ship's computer system (SCS) and the Micro TSG in the 
Hydro Lab sink did not work and the SCS data was merged later by matching maxima 
and minima in the SST and equilibrator temperature data.  The PC clock was found to
be ~ 5:45 early at the start of the cruise and ~ 7:15 early at the end for a time
loss of 1:30 over the length of the cruise.  Consequently, 5:45 was added to the
PC clock time plus an increment equal to the spreadsheet row number divided by
the total number of rows.  The SCS data was then merged using the adjusted PC 
time.
4.	On April 5 and 6 air values were much higher than normal (390 - 420 ppm). 
Most of these were likely caused by stack gas contamination but not all can be
attributed to this source.  Since the ship was far from land at this time, all
air values during the period have been removed.


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