Contact Person:
Name:  Kevin Sullivan
Organization:  NOAA/Atlantic Oceanographic & Meteorological Laboratory
Address:  4301 Rickenbacker Causeway
Phone:  305-361-4382
Email:  Kevin.Sullivan@noaa.gov

Investigator(s):
Name:  Rik Wanninkhof
Organization:  NOAA/AOML
Address:  4301 Rickenbacker Causeway, Miami Fl, 33149
Phone:  305-361-4379
Email:  Rik.Wanninkhof@noaa.gov

Dataset Information:
Funding_Info:  NOAA Climate Program Office; NOAA Ocean Acidification Program
Initial_Submission:  2013/10/01
Revised_Submission:  2013/10/01

Cruise Information:
Experiment Name:  HB1301_L1-4
Experiment Type:  Research Cruise
Cruise_ID (Expocode):  33HH20130314
Cruise_Info:  Spring Bottom Trawl Survey, AOML_SOOP_CO2
Geographical Region:  North Atlantic
Westernmost Longitude:  -76
Easternmost Longitude:  -65
Northernmost Latitude:  45
Southernmost Latitude:  34
Cruise Dates (YYYYMMDD)
Start_Date:  20130314
End_Date:  20130509
Ports of Call:
Newport, RI
Woods Hole, MA
Vessel Name:  Henry B. Bigelow
Vessel ID:  33HH
Vessel Owner:  NOAA

Variables Information:
Variable Name:  xCO2_EQU_ppm
Description of Variable:  Mole fraction of CO2 in the equilibrator headspace (dry) at equilibrator temperature (ppm)
Variable Name:  xCO2_ATM_ppm
Description of Variable:  Mole fraction of CO2 measured in dry outside air (ppm)
Variable Name:  xCO2_ATM_interpolated_ppm
Description of Variable:  Mole fraction of CO2 in outside air associated with each water analysis. These values are interpolated between the bracketing averaged good xCO2_ATM analyses (ppm)
Variable Name:  PRES_EQU_hPa
Description of Variable:  Barometric pressure in the equilibrator headspace (hectopascals)
Variable Name:  PRES_ATM@SSP_hPa
Description of Variable:  Barometric pressure measured outside, corrected to sea level (hectopascals)
Variable Name:  TEMP_EQU_C
Description of Variable:  Water temperature in equilibrator (degrees Celsius)
Variable Name:  SST_C
Description of Variable:  Sea surface temperature (degrees Celsius)
Variable Name:  SAL_permil
Description of Variable:  Sea surface salinity on Practical Salinity Scale (permil)
Variable Name:  fCO2_SW@SST_uatm
Description of Variable:  Fugacity of CO2 in sea water at SST and 100% humidity (microatmospheres)
Variable Name:  fCO2_ATM_interpolated_uatm
Description of Variable:  Fugacity of CO2 in air corresponding to the interpolated xCO2 at SST and 100% humidity (microatmospheres)
Variable Name:  dfCO2_uatm
Description of Variable:  Sea water fCO2 minus interpolated air fCO2 (microatmospheres)
Variable Name:  WOCE_QC_FLAG
Description of Variable:  Quality control flag for fCO2 values (2=good, 3=questionable)
Variable Name:  QC_SUBFLAG
Description of Variable:  Quality control subflag for fCO2 values, provides explanation when QC flag=3

Method Description:
Equilibrator Design:  
Depth of Seawater Intake:  3 meters
Location of Seawater Intake:  Bow
Equilibrator Type:  Sprayhead above dynamic pool, with thermal jacket
Equilibrator Volume:  0.95 L (0.4 L water, 0.55 L headspace)
Water Flow Rate:  1.5 - 2.0 L/min
Headspace Gas Flow Rate:  70 - 150 ml/min
Vented:  Yes
Drying Method for CO2 in Water:  
Gas stream passes through a thermoelectric condenser (~5 °C) and then through a Perma Pure (Nafion) dryer before reaching the analyzer (90% dry).
Additional Information:  Primary equlibrator is vented through a secondary equilibrator
CO2 in Marine Air:  
Measurement:  Yes, 5 readings in a group every 4.3 hours
Location and Height:  Mast above the bridge, ~35 meters above sea surface
Drying Method:  
Gas stream passes through a thermoelectric condenser (~5 °C) and then through a Perma Pure (Nafion) dryer before reaching the analyzer (90% dry).
CO2 Sensor:  
Measurement Method:  Infrared absorption of dry sample gas
Manufacturer:  LI-COR
Model:  6262
Frequency:  Every 140 seconds, except during calibration
Resolution Water:   0.01 microatmosphere
Uncertainty Water:  ± 1 microatmospheres
Resolution Air:  0.01 ppm
Uncertainty Air:  ± 0.2 ppm
Manufacturer of Calibration Gas:  
Scott-Marrin, Inc. - Std 1: JA02645, 204.75 ppm / Std 2: JA02273, 317.49 ppm / Std 3: JA02285, 372.23 ppm / Std 4: JA02647, 518.24 ppm / Std 5: JA03093, 0.00 ppm
CO2 Sensor Calibration:  
The analyzer is calibrated every 4.3 hours with field standards that in turn were calibrated with primary standards that are directly traceable to the WMO scale. The zero gas is ultra-high purity air.
Environmental Control:  
Instrument is located in an air-conditioned laboratory. Ultra-High Purity air (0.0 ppm CO2) and the high standard gas are used to zero and span the LI-COR analyzer.
Method References:  
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.
Sea Surface Temperature:
Location:  After sea water pump, ~3 m below sea surface
Manufacturer:  Seabird
Model:  SBE-38
Accuracy:  ± 0.001 °C
Precision:  0.00025 °C
Calibration:  Factory calibration
Comments:  Manufacturer's Resolution is taken as Precision; Maintained by ship.
Equilibrator Temperature:
Location:  Inserted into equilibrator ~5 cm below water level
Manufacturer:  Hart
Model:  1523
Accuracy:  ± 0.015 °C
Precision:  0.001 °C
Calibration:  Factory calibration
Warming:  0.2 - 0.5 °C
Comments:  Manufacturer's Resolution is taken as Precision.
Equilibrator Pressure:
Location:  Attached to equilibrator headspace
Manufacturer:  Setra
Model:  239
Accuracy:  ± 0.052 hPa
Precision:  0.01 hPa
Calibration:  Factory calibration
Comments:  
Differential pressure reading from Setra-239 attached to the equilibrator headspace was added to the pressure reading from the Setra-270 on the exit of the analyzer to yield the equilibrator pressure. Manufacturer's Resolution is taken as Precision.
Atmospheric Pressure:
Location:  On mast above the bridge at ~35 m above sea surface water
Manufacturer:  Vaisala
Model:  PTB220
Accuracy:  ± 0.15 hPa
Precision:   0.01 hPa
Calibration:  Factory calibration
Comments:  Manufacturer's Resolution is taken as Precision; Maintained by ship.
Sea Surface Salinity:
Location:  In dry lab after a debubbler, next to CO2 system
Manufacturer:  Seabird
Model:  SBE 45
Accuracy:  ± 0.005 permil
Precision:  0.0002 permil
Calibration:  Factory calibration
Comments:  Manufacturer's Resolution is taken as Precision; Maintained by ship.
Other Sensors:
Location:  attached to CO2 analyzer exit to lab
Manufacturer:  Setra
Model:  270
Accuracy:  ± 0.05 hPa
Resolution:  0.015 hPa
Calibration:  Factory calibration
Comments:  
Pressure reading from the Setra-270 on the exit of the analyzer was added to the differential pressure reading from Setra-239 attached to the equilibrator headspace to yield the equlibrator pressure.

Additional Information:
The CO2 analytical system behaved well during most of the four legs of HB1301. Around noon on 11 April, 2013, the instrumental laptop computer froze and about five days of data were lost. Around 17:00 on 16 April, 2013, the connection to the ship's sensors was lost and stayed lost during the last 10 days of leg#3. The data (15-second averages) from the ship's sensors were merged with 5135 CO2 analyses after the cruise.

Data Set Link:
URL:  http://www.aoml.noaa.gov/ocd/gcc/rvbigelow_introduction.php
Label:  AOML Underway fCO2 Data
Link Note:  All AOML fCO2 underway data from the R/V Henry B. Bigelow are posted on this site.

Form Type:
underway