Model-derived estimates of new production: New results point towards lower values

• Published in: Deep Sea Research Part II: Topical Studies in Oceanography
• Main Author: Oschlies, Andreas
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2001
• Subjects: North Atlantic
• Online Access: https://oceanrep.geomar.de/id/eprint/1480/; https://oceanrep.geomar.de/id/eprint/1480/1/1-s2.0-S0967064500001843-main.pdf; https://doi.org/10.1016/S0967-0645(00)00184-3

Model-derived estimates of marine new production are found to display systematic covariations with the underlying model architecture. Almost regardless of the formulation of biogeochemical processes, model-derived estimates of new production have more than doubled from about Full-size image (<1 K) to values around Full-size image (<1 K) when turning from early box models to more recent investigations using coarse-resolution general circulation models. Because none of these models resolves eddies, which have been shown to enhance biological production, a further increase in simulated new production with increasing model resolution might be expected. This study presents results from an eddy-permitting coupled biological–physical model that suggest a basin-scale new production of less than Full-size image (<1 K) for the North Atlantic, i.e. substantially less than values typical for coarse-resolution models. Sensitivity experiments reveal that the amount of diapycnal mixing, described either explicitly or implicitly in the numerical discretization schemes, has a considerable effect on the simulated input of nutrients into the euphotic zone. Implications for coarse-resolution models used until now are that unrealistically high levels of explicit and implicit diapycnal diffusion may have been responsible for unrealistically high estimates of new production.