M/V Celtic Explorer cruise:		GO-SHIP A02 transit
Expocode:	45CE20170420

This work was carried out with the support of the Irish Marine Institute and funded under the Marine Research Programme by the Irish Government.

Initial submission:		2019
Most recent update:		09. January 2019

Date of cruise (dd/mm/yyyy):	20.04.- 25.04.2017
Geographic coverage: 		54°N, 20°W – 50°N, 51°W
Ports of call: 			Galway, Ireland - St. John's, Canada

Vessel name:	R/V Celtic Explorer
Vessel ID:	9244439
Country:	Ireland
Owner:		Marine Institute

PI:		Margot Cronin (Marine Institutestitute/Ireland)
		
Contact: Margot Cronin, margot.cronin@marine.ie


Reported  variables:
(1-3)	Year|Month|Day		date
(4-6)	Hour|Minute|Second		time (UTC)
(7)	Day of year			decimal year day
(8)	Longitude [deg E]		Longitude in decimal degrees E
(9)	Latitude [deg N]		Latitude in decimal degrees N
(10)	SST [deg C]			Sea surface temperature in deg C
(11)	SSS				Sea surface salinity 
(12) 	Atm. Pressure [mbar]		Atmospheric pressure in mbar
(13)	Equi Temp [deg C]		Water temperature inside the equilibrator in deg C
(14)	Equi Press [mbar]		Pressureinside the equilibrator in mbar
(15)	xCO2 (equi temp, dry) [ppm]	mole fraction of CO2 in the equilibrator 
      headspace (dry) at equilibrator  temperature in ppm	
(16)	pCO2 (SST, 100hum) [uatm]	partial pressure of CO2 in seawater at SST and
      100% humidity in µatm
(17)	fCO2 (SST, 100hum) [uatm]	fugacity of CO2 in seawater at SST and
      100% humidity in µatm
(18)	Atm. xCO2 (dry) [ppm]		mole fraction of CO2 of atmospheric air in ppm
(19)	Atm xCO2 (dry, running mean) [ppm]	same as 18 but with a running mean (600 minutes) to 
						interpolate between measurements.

Instrument information:
- SST (± 0.05 deg C):
SST was measured with a thermosalinograph from Seabird (SBE21) with an external SBE38 which was installed close to the seawater intake. Both instruments were calibrated approximately every 6 months. 

-Equilibrator temp (±0.05 °C):
Equilibrator temperature is measured by a Fluke Hart 1521, wich is known to be stable over a longer period. The GO-8050 was bought 6 months prior to the survey. The thermometer was calibrated before purchase.

-SSS (± 0.5 PSU):
SSS was measured with a thermosalinograph from Seabird (SBE21) which was calibrated approximately every 6 months. 

-Atmospheric press. (± 0.1 mbar):
Atmospheric pressure was measured at approximately 6 m height and pressure is corrected to sea level.

-Equilibrator press (± 0.1 mbar):
The equilibrator is open to the atmosphere. The pressure outside the equilibrator is measured directly next to the equilibrator by a DRUCK pressure sensor (model no 270). A SETRA 
difference pressure sensor is attached to the equilibrator.

-pCO2/fCO2 (±2µatm):	
Accuracy of pCO2/fCO2 data was recalculated to be better than 2 µatm.
	IR sensor:		Licor 7000, calibrated with 3 non-zero standard gases.
	Standard gases:		(198.3, 399.3, 606.5), calibrated according to WMO standards.
	Water flow rate: 	2-3 L min-1
	Gas flow rate:		ca. 100 mL min-1

A so-called GO system was used for pCO2 measurements. The system is described in detail in Pierrot (2009). Surface water is pumped continuously from the intake to the equilibrator. The equilibrator contains a water spray head, and as the water flows through it the dissolved CO2 equilibrates with the headspace. The headspace is dried and xCO2 is determined by an infrared sensor. Calculations were performed following Pierrot (2009) and are described in detail in Steinhoff (2010). The data reduction was done in cooperation with Tobias Steinhoff (tsteinhoff@geomar.de).


References:
Pierrot, D., Neill, C., Sullivan, K., Castle, R., Wanninkhof, R., Lüger, H., Johannessen, T.,
Olsen, A., Feely, R. A., and Cosca, C. E. (2009). Recommendations for autonomous underway
pCO2 measuring systems and data reduction routines. Deep-Sea Res. II , 56, 512_522.

Steinhoff, T. (2010). Carbon and nutrient fluxes in the North Atlantic Ocean. Dissertation. http://eldiss.uni-kiel.de/macau/receive/dissertation_diss_00005704