First description of the Minnesota Earth System Model for Ocean biogeochemistry

First description of the Minnesota Earth System Model for Ocean biogeochemistry pdf, tutoriel & guide de travaux pratiques en pdf.

Rationale for improving GENIE-1

There is still significant room to improve the transient tracer uptake in GENIE-1. The model-predicted 1994 global ocean inventories of CFC-11 is 0.88×109 mol and anthropogenic carbon is 171PgC (Ridgwell et al., 2007). The corresponding observational estimates based on WOCE and JGOFS surveys are much lower at 0.55±0.08×109 mol CFC11 (Willey et al., 2004) and 118±19PgC (Sabine et al., 2004). If we consider the roughly +7% systematic bias in the anthropogenic carbon inventory (Matsumoto and Gruber, 2005), the overestimation of this transient tracer uptake by GENIE-1 is even more significant. While these uptakes reflect excessive intermediate water ventilation in GENIE-1, there also needs to be a good match in the deep ocean ventilation. This brings us to the third reason, which is that the deep ocean ventilation of GENIE-1 ought to be validated with the observed abundance of natural radiocarbon (14C). A community-wide OCMIP-2 study that compared 19 ocean carbon cycle models used deep ocean radiocarbon as a met ric to evaluate the models (Matsumoto et al., 2004). This metric has since been used in subsequent descriptions of new carbon cycle models (Muller et al., 2006; Schmittner et al., 2005) and is arguably the most effective means to evaluate ocean models with respect to deep ocean circulation. The final motivation for improving GENIE-1 is to incorporate as much seasonality as possible. The simplicity of GENIE-1 with the momentum and radiation forcings being annual averages makes the model more appropriate for seeking mean climate states in long term integrations. Examples include studies of the geologic past to document changes in marine sedimentation (Chikamoto et al., 2008; Ridgwell, 2007). For postindustrial changes, the presence of seasonality adds more credibility in general and helps achieve more realistic processes such as seasonal production and formation of polar sea ice.