RB1103 Readme Flie

Ship:             NOAA research vessel Ronald H. Brown
Cruise Start:     Rio de Janeiro, Brazil, November 6, 2011
Cruise End:       Bridgetown, Barbodos, November 17, 2011
Chief Scientists: N/A
System Operator:  Jonathan Shannahoff
Expocode:         33RO20111106

Method:
The system was built by General Oceanics (GO) and is described in 
Pierrot, et al. (2009).  The four standard gases come from CMDL in 
Boulder and are directly traceable to the WMO scale.

Sampling Cycle:
The system runs on an cycle during which 4 standard gases, 5 air 
samples from the bow tower and 50 surface water samples (from the 
equilibrator head space) are analyzed on the following schedule:

1. Zero and span of Licor
2. Four standard gases
3. Five air samples
4. Fifty equilibrator headspace gas samples
5. Repeat steps 2 - 4 nine more times
6. Restart from step 1

Standards:  CA06709: 284.75 ppm, CA02813: 363.24 ppm, 
CA07921: 423.57ppm, CA07931: 545.88 ppm.

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. The pCO2 system was removed from the ship on May, 2010 and reinstalled on September. 
After that, recorded licor pressure values were 7 hPa higher than sea level pressures. 
However, historical data showed that licor pressure values were slightly lower than 
sea level pressures. There were no possible mechanisms that could increase the licor 
pressure as much as 7 hPa. It was concluded that the recorded licor pressure values 
were incorrect. So, the licor pressure values were estimated from the sea level 
pressures using a constant offset of -0.80 hPa. The offest was calcualted from data 
collected for the 5 previous cruises (RB0901, RB0902, RB0903, RB0904 in 2009 and 
RB2010_PNE in 2010, n=48,953). 

2. During the processing of the data, it was determined that there was a 2.47 minute 
offset between the SST data record (i.e. SBE21 in the instrument chest) and the 
equilibrator temperature data record. The water takes about 2.47 minutes to travel 
from the inlet at the hull to the analytical equilibrator.

3. January 2017 made minor format changes to the header, added expocode and changed missing value to -999. Data was not altered.  

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


Pierrot, D., C. Neil, K. Sullivan, R. Castle, R. Wanninkhof, H. Lueger, 
T. Johannson, A. Olsen, R. A. Feely, and C. E. Cosca (2009),
Recommendations for autonomous underway pCO2 measuring systems 
and data reduction routines, Deep-Sea Res II, 56, 512-522.