RB-03-02
Puerto Rico Trench Readme File

Ship:			NOAA research vessel Ronald H. Brown
Cruise Start:		Miami, FL, February 19, 2003
Cruise End:		San Juan, Puerto Rico, March 7, 2003
Chief Scientist:	Uri Ten Brink
System Operator:	Jonathan Shannahoff
Expocode:               33RO20030219

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 hectopascals (hPa) assuming 100 % humidity at the 
equilibrator temperature.

Notes:
1.	Any values outside the range of the standards (295.37, 357.18, & 423.28 ppm) 
should be considered approximate (within 5 ppm).  While individual data points above 
423 or below 293 may not be accurate, the general trends should be indicative of the 
seawater chemistry.
2.  The TSG temperature and salinity readings were "stuck" at a constant value on 
Feb. 20 from 18:38 to 18:52 and on Feb. 26 from 12:30 to 15:15.  I did a linear
interpolation from the last "non-stuck" value to the next "non-stuck" value.  The
difference in fCO2 values should be much less than 1 hectopascal for these samples.
3.  Some air values were removed because they were anomalously high or because of
probable contamination by stack gas.  Some air values were slightly higher than the
baseline of approximately 376 ppm and the high values could not be attributed to
stack gas.  These values have been left in the data file and given a flag of 3 and
are likely due to winds coming from the island of Puerto Rico.


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