Popova, E.E., I.J. Totterdell and A. Coward

Southampton Oceanography Centre, Empress Dock, Southampton SO14 3ZH UK, Tel: ++ 44 (0)23 80596347, Fax: ++ 44 (0)23 80596247, E-mail: ekp@soc.soton.ac.uk

JGOFS time series: How well do global models reproduce them?

We present results obtained from two global biogeochemical models: the Hadley Centre Ocean Carbon Cycle (HadOCC) model, based on HADOM3L, and BIO-OCCAM. In both cases the physical models are Bryan-Cox based level models the most important difference between them being the level of spatial resolution. HADOM3L has 2.5 ^o x 3.75 ^o and OCCAM is 1^o horizontal resolution. Ecosystem models embedded into general circulation models are of similar complexity and includes Phytoplankton, Zooplankton, Nitrate, Detritus as model states variables with an addition of Ammonium in OCCAM.

We compare two model runs and available observations for main JGOFS sites (BATS, HOT, KERFIX, Station P) and Process Study sites (Arabian Sea, Equatorial Pacific, NABE, Ross Sea and Antarctic Polar front Zone). Focus of our attention is the annual cycles of Chl-a, nutrients and primary and new productions with upper mixed layer dynamics being the main driven force for their variability. In areas where both models show a satisfactory agreement with data we make a cross-comparison of fluxes through the ecosystems. We discuss performance of both models and make suggestions about additional level of biological model complexity needed in order to reach optimal agreement between models and observations.