Gasex98 Leg 3 Readme File

Ship:			NOAA research vessel Ronald H. Brown
Cruise Start:		Punta Del Gado, Azores, June 28, 1998
Cruise End:		Miami, FL, July 7, 1998
Chief Scientist:	Shari Yvon-Lewis
System Operator:	Craig Neill
Expocode:               33RO19980628  

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 3:
1. Gas flow in the water phase was low (but adequate) until June 30 @ 
1100 GMT.
2. On July 3 from 0230 to 0330 the system was down due to a power 
failure.
3. On July 5 at 1545 GMT the standard tanks were changed from 
275.63=Low, 297.74=Mid, & 360.62=High to 297.74=Low, 360.62=Mid, & 
408.35=High.

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