Model of Ocean Biogeochemistry and Isotopes (MOBI)

MOBI includes three phytoplankton classes (nitrogen fixers a.k.a. diazotrophs, calcifiers a.k.a. coccolithophores and other phytoplankton), nitrate (NO3), phosphate (PO4) and dissolved iron (DFe) as interactive nutrients, zooplankton, and detritus (dead particulate organic matter). Calcium carbonate (CaCO3) is a prognostic variable. Its production is calculated as a fraction of the detritus produced by coccolithophores and zooplankton and it is sinking into the deep ocean where it dissolves. Nitrogen (15N) and carbon (13C) isotopes are included in all compartments. Radiocarbon (14C) is included only in the dissolved inorganic carbon (DIC) component. Dissolved oxygen (O2) controls denitrification in the water column. Benthic denitrification is calculated considering subgridscale bathymetry. Dissolved organic matter is calculated separately for carbon, nitrogen and phosphorous (DOC, DON, DOP).

Versions of MOBI have been implemented in various physical models such as the UVic model (e.g. Muglia et al., 2017), the Japanese Earth System Model MIROC (Yamamoto et al., 2015), VEROS and the transport matrix (Khatiwala et al., 2019). It is used by many scientists around the world. The newest version (2.0) is very flexible and allows many different configurations from a simple, 1 nutrient NPZD model with 4 prognostic tracers to the most complex one as depicted in the above figure with 30 prognostic tracers.