Plueddemann Moorings 2002 Readme File



Ship:			NOAA research vessel Ronald H. Brown

Cruise Start:		Bridgetown, Barbados, Mar. 3, 2002

Cruise End:		Bridgetown, Barbados, Mar. 7, 2002

Chief Scientist:	N/A

System Operator:	Jonathan Shannahoff



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 (292, 340, & 431 ppm) 

should be considered approximate (within 5 ppm).  While individual data points above 

431 may not be accurate, the general trends should be indicative of the seawater 

chemistry.

2. The low standard cylinder was changed on March 4 to 275.63.  Some values were 

removed at this time because of the change.  After the change, the air values 

increased by ~2 ppm.  We have been unable to determine the cause of this and have

left the values in the data file.

3. The equilibrator thermistor was reading incorrectly up until the time of the

cylinder change.  I have substituted a derived value for equilibrator temperature for

the first part of the cruise using the YSI TSG temperature as follows:

EqT = 0.9401 * YSI T + 1.334 (r^2 = 0.8904).  This equation was derived from values

after the cylinder change where comparisons with SST and the YSI indicate the thermistor

was reading correctly. 



For questions or comments contact:

Bob Castle

4301 Rickenbacker Causeway

Miami, FL 33149

305-361-4418

castle@aoml.noaa.gov