WOCE section AR7E Northern Ireland - Southern Greenland CarboOcean 2005, 2007

1. Preliminary Results CARBOOCEAN WOCE AR7E section 2005, 2007Hein de Baar, Steven van Heuven, Hendrik van Akenand many others

2. WOCE section AR7ENorthern Ireland - Southern GreenlandCarboOcean 2005, 2007 Central Irminger Sea Time Series Moorings NIOZ YoYo-CTD, etc. AR7E section Repeat sections RV Pelagia by Royal NIOZ and University of Groningen

3. 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

4. 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

5. Average increase in DIC from 1981 to 2005 is 13.2 µmol/kg Steven van Heuven, Hein de Baar, Hendrik van Aken

6. Average decrease in pH from 1981 to 2005 is 0.0323 Steven van Heuven, Hein de Baar, Hendrik van Aken

7. Shoaling of aragonite horizon 1981 Black line is aragonite saturation horizon (omega=1) Steven van Heuven, Hein de Baar, Hendrik van Aken

8. Shoaling of aragonite horizon 2005 Black line is aragonite saturation horizon (omega=1) Steven van Heuven, Hein de Baar, Hendrik van Aken

9. 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

10. Shoaling of aragonite horizon ? 2007 Black line is aragonite saturation horizon (omega=1) Steven van Heuven, Hein de Baar, Hendrik van Aken

11. 1981 2005 2007 Shoaling of aragonite horizon ?? • variability of water mass hydrography, Hendrik van Aken • - also use yoyo-CTD time series for hydrography variability

12. 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

13. pH decrease DIC increase