M/V Atlantic  Companion cruise:		COM14-03

This work was supported through EU FP7 project CARBOCHANGE “Changes in carbon uptake and emissions by oceans in a changing climate”  which received funding from the European Community’s Seventh Framework Programme under grant agreement  no. 264879. This work was also supported by the German component of the Integrated Carbon Observing System (ICOS-D) which received funding by BMBF under grant agreement 01LK1101C.

Initial submission:		2014
Most recent update:		22. Jul 2014

Date of cruise (dd/mm/yyyy):	22.02. - 26.02.2014
Geographic coverage: 		52°N, 7°W – 44°N, 63°W
Ports of call: 			Halifax, Canada - Liverpool, UK

Vessel name:	M/V Atlantic Companion
Vessel ID:	SKPE
Country:	Sweden
Owner:		Atlantic Container Lines

PI:		Tobias Steinhoff
		GEOMAR Helmholtz Centre for Ocean Research Kiel
		Duesternbrooker Weg 20
		24105 Kiel
		Germany
		tsteinhoff@geomar.de

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 (± 0.05 deg C):
SST was measured with a thermosalinograph from Seabird (SBE21) with an external SBE38 which was installed approximately 30 cm after the seawater intake. Both instruments were calibrated approximately every 6 months. 

-Equilibrator temp (±0.05 °C):
The temperature probe inside the equilibrator was compared to the SBE38 every 3 months.


-SSS (± 0.1 PSU):
SSS was measured with a thermosalinograph from Seabird (SBE21) which was calibrated approximately every 6 months. 

-Atmospheric press. (± 0.1 mbar):
The atm. Pressure was not measured during this cruise. But on former cruises a constant offset of ca. 2 mbar was observed between atm. press and equ. press. Therefore the atm. press was calculated as follows: atm. press = equ. press - 2 mbar.

-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 SETRA pressure sensor (model no 270).

-pCO2/fCO2 (±3µatm):	
	IR sensor:		Licor 7000, calibrated with 2 standard gases.
	Standard gases:		Deuste Steininger (249.3, 348.06), calibrated against 
      NOAA/CMDL standard gases. Resulting uncertainty: +- 0.5 ppm.
	Water flow rate: 	2-3 L min-1
	Gas flow rate:		100 mL min-1

A so-called Neill system was used for pCO2 measurements. The system is described in detail in Pierrot (2009) and the whole setup is described in Steinhoff (2010). Surface water is pumped continuously (by a torque flow pump) 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). 
Due to noisy atmospheric xCO2 measurements, they are only reported where the standard deviation of 5 measurements were below 0.5 ppm.

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