A coarse resolution North Atlantic ocean circulation model: an intercomparison study with a paleoceanographic example

Paleoreconstructions suggest that during the\udLast Glacial Maximum (LGM) the North Atlantic circulation was noticeably\uddifferent from its present state. However, the glacial salt conveyor belt is\udbelieved to be similar to the present-day's conveyor, albeit weaker and\udshallower because of an increased freshwater flux in high-latitudes. We present\udhere the investigation of the conveyor operation based on ocean circulation\udmodelling using two numerical models in parallel. The GFDL primitive equation\udmodel and a planetary geostrophic model are employed to address the problem of\udthe paleocirculation modelling in cases of uncertain and sparse data comprising\udthe glacial surface boundary conditions. The role of different simplifications\udthat may be used in the ocean climate studies, including the role of grid\udresolution, bottom topography, coast-line, etc., versus glacial-interglacial\udchanges of the ocean surface climatology is considered. The LGM reverse conveyor\udgyre appeared to be the most noticeable feature of the glacial-to-interglacial\udalteration of the ocean circulation. The reversed upper-ocean conveyor, weaker\udand subducting 'normal' conveyor in the intermediate depths, and the change of\udthe deep-ocean return flow route are robust signatures of the glacial North\udAtlantic climate. The results are found to be 'model-independent' and fairly\udinsensitive to all factors other than the onset of the glacial surface\udconditions