R/V Celtic Explorer cruise
Expocode:	45CE20170524

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:		08. December 2019

Date of cruise (dd/mm/yyyy):	15.10. - 04.11.2017
Geographic coverage: 		53°N, 11°W – 50°N, 5°W
Ports of call: 			Galway, Cobh, Galway

Vessel name:	R/V Celtic Explorer
Vessel ID:	EIGB
Country:	Ireland
Owner:		Ireland

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

Citation
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 (500 minutes) to 
						interpolate between measurements.

Instrument information:
- SST (± 0.001 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 12 months. 

-Equilibrator temp (±0.05 °C):
Equilibrator temperature is measured by a Fluke Hart 1523, wich is known to be stable over a longer period. It was calibrated in 2016.

-SSS (± 0.5 PSU):
SSS was measured with a thermosalinograph from Seabird (SBE21) which was calibrated approximately every 12 months. 

-Atmospheric press. (± 0.1 mbar):
Atmospheric pressure was measured using a Druck barometer with a precision of 0.2%. The sensor is installed at approximately 5m height 
and pressure is corrected to sea level.

-Equilibrator press (± 2 mbar):
The equilibrator is open to the atmosphere. Since no absolute pressure sensor was installed the pressure from the atmospheric pressure sensor was used.
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:		Manufactued - Air Products, Calibrated - Mace Head Research Station (198.29 399.28 606.52])
	Water flow rate: 	2-3 L min-1
	Gas flow rate:		80 - 180 mL min-1 (equilibrator and standard gas flow was 100 mL min-1, atm flow rate was 180 mL min-1)

A General Oceanics pCO2 system (model 8050) was used for pCO2 measurements. The system is described in detail in Pierrot et al.(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). 

Remarks during data reduction:
- using computer time instead of GPS time. Difference below 2 seconds
- condenser didn't work properly. Temperature was between 10 and 14 degC
- using deck box pressure for atm pressure and lab pressure
- 500 min running mean for atm xCO2 and fCO2
- 1348 data points


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