Gasex98 Leg 2 Readme File

Ship:			NOAA research vessel Ronald H. Brown
Cruise Start:		Lisbon, Portugal, May 25, 1998
Cruise End:		Punta Del Gado, Azores, June 26, 1998
Chief Scientist:	Rik Wanninkhof
System Operator:	Bob Castle
Expocode:               33RO19980525 

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 for Leg 2:
1. On May 29 some small air leaks in the system were discovered and 
repaired.  Data prior to 2030 GMT shows higher variability than 
normal.
2. On May 30 from 2330 to 2400 GMT positive pressure in equilibrator 
caused headspace gas to back up into the Licor sample cell, 
resulting in bad readings.
3. On May 31 from 2115 to 2300 GMT the system was down to install a 
solenoid valve on the sample output of the Licor.
4. On June 3 from 1412 to 1825 the system was down to recalibrate the 
YSI TSG.
5. On June 9 from 545 to 625 the system was down to clean the 
equilibrator's shower head.
6. On June 12 from 1225 to 1312 the system was down to install a 
bounceless switch on the Valco valve.
7. On June 12 from 1430 to 1600 the system was down to recalibrate the 
YSI O2 sensor.
8. On June 17 from 1505 to 1930 the system was down to recalibrate the 
YSI O2 sensor.
9. On June 25 from 1315 to 1640 the system hung due to operator error.

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