RB1101  PNE Readme Flie

Ship:             NOAA research vessel Ronald H. Brown
Cruise Start:     Charleston, SC, July 21, 2011
Cruise End:       Cape Town, South Africa, August 20, 2011
Chief Scientists: Rick Lumpkin
System Operator:  Jonathan Shannahoff
Expocode:         33RO20110721

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 offset was calculated 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 is a 2.5 minute 
offset between the SST data record (i.e. SBE21 in the instrument chest) and the 
equilibrator temperature data record. The water takes about 2.5 minutes to travel 
from the inlet at the hull to the analytical equilibrator.

3. During January and February 2017 minor format changes were made to the header, 
the expocode was added to the data file, and value representing missing data was changed 
from -9 to -999.  Additional raw data were processed along with the original data.  

For questions or comments contact: 
Kevin Sullivan
4301 Rickenbacker Causeway 
Miami, FL 33149 
305-361-4382 
kevin.sullivan@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.