MESMO 3: Flexible phytoplankton stoichiometry and refractory dissolved organic matter

We describe the third version of Minnesota Earth System Model for Ocean biogeochemistry (MESMO 3), an Earth system model of intermediate complexity, with a dynamical ocean, dynamic-thermodynamic sea ice, and an energy-moisture-balanced atmosphere. A major feature of version 3 is the flexible C : N : P ratio for the three phytoplankton functional types represented in the model. The flexible stoichiometry is based on the power law formulation with environmental dependence on phosphate, nitrate, temperature, and light. Other new features include nitrogen fixation, water column denitrification, oxygen and temperaturedependent organic matter remineralization, and CaCO3 production based on the concept of the residual nitrate potential growth. In addition, we describe the semi-labile and refractory dissolved organic pools of C, N, P, and Fe that can be enabled in MESMO 3 as an optional feature. The refractory dissolved organic matter can be degraded by photodegradation at the surface and hydrothermal vent degradation at the bottom. These improvements provide a basis for using MESMO 3 in further investigations of the global marine carbon cycle to changes in the environmental conditions of the past, present, and future.