Inorganic carbon time series at Ocean Weather Station M in the Norwegian Sea

I. Skjelvan (1, 2) , E. Falck (2) , F. Rey (3) , S. B. Kringstad (1, 2)

1 BCCR - Bjerknes Centre for Climate Research
2 GFI / BiU - Geophysical Institute [Bergen]
3 IMR - Institute of Marine Research [Bergen]

Dissolved inorganic carbon (C_T) has been collected at Ocean Weather Station M (OWSM) in the Norwegian Sea since 2001. Seasonal variations in C_T are confined to the upper 50 m, where the biology is active, and below this layer no clear seasonal signal is seen. From winter to summer the surface C_T concentration typical drops from 2140 to about 2040 ?mol kg^?1, while a deep water C_T concentration of about 2163 ?mol kg^?1 is measured throughout the year. Observations show an annual increase in salinity normalized carbon concentration (nC_T) of 1.3±0.7 ?mol kg^?1 in the surface layer, which is equivalent to a pCO₂ increase of 2.6±1.2 ?atm yr^?1, i.e. larger than the atmospheric increase in this area. Observations also show an annual increase in the deep water nC_T of 0.57± 0.24 ?mol kg^?1, of which about a tenth is due to inflow of old Arctic water with larger amounts of remineralised matter. The remaining part has an anthropogenic origin and sources for this might be Greenland Sea surface water, Iceland Sea surface water, and/or recirculated Atlantic Water. By using an extended multi linear regression method (eMLR) it is verified that anthropogenic carbon has entered the whole water column at OWSM.

Domaines: Cosmologie et astrophysique extra-galactique [astro-ph.CO]; Astrophysique [astro-ph]; Interfaces continentales, environnement; Océan, Atmosphère; Sciences de la Terre

I. Skjelvan, E. Falck, F. Rey, S. B. Kringstad. Inorganic carbon time series at Ocean Weather Station M in the Norwegian Sea. Biogeosciences Discussions, 2007, 4 (4), pp.2929-2958. ⟨hal-00297915⟩