Quoted from: Ilyina, Tatiana, Katharina D. Six, Joachim Segschneider, Ernst Maier‐Reimer, Hongmei Li, and Ismael Núñez‐Riboni. "Global ocean biogeochemistry model HAMOCC: Model architecture and performance as component of the MPI‐Earth system model in different CMIP5 experimental realizations." Journal of Advances in Modeling Earth Systems 5, no. 2 (2013): 287-315.  https://doi.org/10.1029/2012MS000178 

Ocean biogeochemistry as part of the Earth system controls the uptake of atmospheric CO2 and storage of carbon in the ocean on the timescale from days to millennia. The longest timescales of the marine carbon cycle are related to sediment and weathering processes. Hence, in this model description we divide processes simulated by HAMOCC into three major categories. These are biogeochemistry of the water column (including organic and inorganic carbon cycle processes), sediment biogeochemistry, and interactions with the atmosphere. The key components of the model HAMOCC are given in Figure 1. The model in the configuration described here has 17 state variables calculated prognostically in the water column (listed in Table 1) and 12 state variables in the sediment. Modifications in the model version HAMOCC 5.2 following the technical report by Maier‐Reimer et al. [2005] which are incorporated in the CMIP5 experimental design are described in the following sections. These include: correction of temperature fit in air‐sea exchange [Gröger and Mikolajewicz, 2011], temperature‐dependent photosynthesis, sulphate reduction, iron as pore water tracer (in the sediment module), remineralization in the euphotic layer, compensation of loss of shell material (silicate, alkalinity, and dissolved inorganic carbon) to sediment during long spin‐up runs, changes in alkalinity during denitrification and nitrogen fixation, and output routines to address CMIP5 requirements.