MOMBA 1.1 – a high-resolution Baltic Sea configuration of GFDL's modular ocean model

Abstract

Abstract. We present a new coupled ocean circulation – ice model configuration of the Baltic Sea. The model features, contrary to most existing configurations, a high horizontal resolution of ≈1 nautical mile which is eddy resolving over much of the domain. The vertical discretisation comprises a total of 47 vertical levels. Results from a 1987 to 1999 hind cast simulation show that the model's fidelity is competitive. As suggested by a comparison with sea surface temperatures observed from space, this applies especially to near-surface processes. Hence, the configuration is well suited to serve as a nucleus of a full-fledged coupled ocean circulation biogeochemical model (which is yet to be developed). A caveat is that the model fails to reproduce major inflow events. We trace this back to spurious vertical circulation patterns at the sills which may well be endemic to high resolution models based on geopotential coordinates. Further, we present indications that – so far neglected – eddy/wind effects exert significant control on wind-induced up- and downwelling.