The ecosystem model consists of physical and biological submodels in the water column and sea ice. The two models interact through nutrients transport between water and ice interface and ice algae sinking into the water column.
The 1-D physical and biological models in water column are described in detail in Jin et al. (2005). Since the sea is fully covered by fast ice during the model period (March to June), the water temperature is considered constant at freezing point. The biological model has nine compartments: two phytoplankton (diatom and flagellates: D and F), three zooplankton (small copepods, large copepods, and microzooplankton: ZS, ZL, ZP), three nutrients (nitrate+nitrite, ammonium, silicon: NO3, NH4, Si) and detritus (Det).
The sea ice ecosystem model focuses on the bottom 2cm skeletal layer. Due to lack of understandings from observations, Arrigo et al. (1993) parameterized zooplankton grazing in a similar mathematical form as respiration, which is actually equivalent to increasing respiration coefficient. In this study, the grazing term in sea ice is therefore not included in the equations explicitly. The observed ice thickness and temperature are interpolated into each time step instead of using an ice dynamic model. The biological dynamics in sea ice are expressed as follows:

Table 2. List of parameter values and conversion ratios

References:
Wang, J., C. Deal, Z. Wan, M. Jin, N. Tanaka and M. Ikeda, 2003. User’s Guide for a Physical-Ecosystem Model (PhEcoM) in the Subpolar and Polar Oceans. International Arctic Research Center-Frontier Research System for Global Change, Tech. Rep. 02-02, 69 pp.

Jin, M. C.J. Deal, J. Wang, K.-H. Shin, N. Tanaka, T. Whitledge, S. H. Lee, R.R. Gradinger, 2006. Controls of the landfast ice-ocean ecosystem offshore Barrow, Alaska. Annals of Glaciology (iin press)

Jin, M., C.J. Deal, J. Wang, N. Tanaka, and M. Ikeda, 2006. Vertical mixing effects on the phytoplankton bloom in the southeastern Bering Sea mid-shelf. J. Geophys. Res., 111, C03002, doi:10.1029/2005JC002994.

Deal, C.J., M. Jin, J. Wang, N. Tanaka, M. Ikeda, T. Whitledge and T. Rho, 2006. Dynamics of plankton and nutrients in the Bering Sea: An ecosystem model study with special focus on the coccolithophore bloom and water column nitrification (submitted to Prog. Oceanogr.)