Preliminary Results CARBOOCEAN

WOCE AR7E section 2005, 2007

Hein de Baar, Steven van Heuven, Hendrik van Aken

and many others

WOCE section AR7ENorthern Ireland - Southern Greenland

CarboOcean 2005, 2007

Repeat sections RV Pelagia by Royal NIOZ and University of Groningen

Central Irminger SeaTime Series Moorings

NIOZYoYo-CTD, etc.

AR7E section

Compare with paleo-proxyCO2 data of the previous century

• 1930's Wattenberg (Kiel), Meteor expedition– data of historical interest only

– no stations near Iceland-Greenland

• GEOSECS 1970's– acid titration for Alk and DIC (Edmond, Bradshaw et al)

– only few stations near Iceland-Greenland

• 1981 Transient Tracers in the Oceans TTO-NAS– improved titrator design (Bradshaw, Brewer, Sachs et al.)

– improved thermostat control etc. etc.

– DIC values from titrators has reproducibility of circa 10-12 micromol

– better DIC value calculated via pCO2 etc (Tanhua, Wallace, 2005)

– error bars of circa 4-6 micromol for Alk and DIC

• Coulometry better 1-2 micromol reproducibility, JGOFS-NABE 1989 etc• 1993-1994 onwards cruises have modern accuracy, e.g. CLIVAR

– Coulometry plus Dickson certified standards

Compare with paleo-proxyCO2 data of the previous century

• 1981 Transient Tracers in the Oceans TTO-NAS (Brewer, Bradshaw etal)

– better DIC value calculated via pCO2 etc (Tanhua, Wallace, 2005)

– error bars of circa 4-6 micromol for Alk and DIC

Average increase in DIC from 1981 to 2005 is 13.2 µmol/kg

Steven van Heuven, Hein de Baar, Hendrik van Aken

Average decrease in pH from 1981 to 2005 is 0.0323

Steven van Heuven, Hein de Baar, Hendrik van Aken

Shoaling of aragonite horizon

Black line is aragonite saturation horizon (omega=1)

Steven van Heuven, Hein de Baar, Hendrik van Aken

1981

Shoaling of aragonite horizon

Black line is aragonite saturation horizon (omega=1)

Steven van Heuven, Hein de Baar, Hendrik van Aken

2005

So far, so good ?

• 1981-2005 trends of DIC, pH, omega-aragonite are in expected directions

• 2 datapoints (1981, 2005) is adequate in geochemistry ('Turekian truism')

• reconstructed 1981 TTO data remains less solid than modern 2005 data

Shoaling of aragonite horizon ?

Black line is aragonite saturation horizon (omega=1)

Steven van Heuven, Hein de Baar, Hendrik van Aken

2007

1981

2005

2007

Shoaling of aragonite horizon ??

- variability of water mass hydrography, Hendrik van Aken

- also use yoyo-CTD time series for hydrography variability

Future work• completion of Carina database

– systematic integral corrections of offsets between datasets of ALL North Atlantic cruises

– will yield best possible 'final' values of 'paleoproxy' CO2 data of previous century

• process data of recent cruises– AR7E September 2007 (Steven van Heuven etal.)– North Atlantic Ireland-Madeira, November 2007 (Steven van Heuven)– hydrography variability– direct comparison with 'paleo'-cruises– algorithms to resolve anthropogenic CO2 (Gruber method, TROCA, and

others)

• 2009/2010 PhD thesis Steven van Heuven – on deep North Atlantic CO2 changes

DIC increase pH decrease