Vents98 Leg 1 Readme File

Ship:			NOAA research vessel Ronald H. Brown
Cruise Start:		Newport, OR, July 30 1998
Cruise End:		Victoria, BC, Canada, August 15 1998
Chief Scientist:	Ed Baker
System Operator:	Dana Greeley
Expocode:               33RO19980730 

Method:
Infrared absorption of dry gas.  Measurement of fugacity of Carbon 
Dioxide in surface water and air using continuous sampling methods.  
See Wanninkhof and Thoning, 1993 in Marine Chemistry, 44, 189-205 
for details of the system.  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).

Notes for Leg 1:
1. For the first four hours low gas flow in the high standard phase (std 
3) resulted in slightly depressed voltage readings due to inadequate 
flushing of the Licor's sample cell.  Since the voltages in both air 
and water phases were at most only slightly higher than the mid 
standard gas, I have retained all of the original values without 
applying a correction.
2. On August 9 from 0030 through 0430, the ship conducted towing 
operations that caused stack gas to enter the intake during the air 
phase.  All air values for this period have been removed.
Nov. 30, 2000:
3. The feed from the ship's computer system (SCS) gave only 3 significant
digits in latitude and longitude for the first 224 rows in the data file.
I 'fixed' this by interpolating values in both the latitude and longitude
columns.  This should be a fairly close approximation to the actual cruise
track.  If I can locate the original data from the ship, I will replace the
interpolated values with the actual ones.


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