Reconstruction of the glacial atlantic circulation with an inverse model under a geostrophic constraint

The inverse ocean model 2RAIOM is presented. It is used to reconstruct the mean ocean circulation from oceanic data of temperature and salinity. 2RAIOM extends a previous model by adding two terms to the cost function: The so-called dynamic geostrophy enforces the consistency of the circulation with temperatures and salinities; the other term considers the wind stress and turns out to be important for sparse data situations like the geological past. Numerical experiments are performed for the Atlantic Ocean with recent data and with data of the Last Glacial Maximum (LGM).2RAIOM is able to obtain stable reconstructions of the large scale features of the oceanic circulation. However, the derived small scale patterns vary strongly for small changes in the input data. For the LGM we find evidence of a weakening of the North Atlantic Deep Water production.2RAIOM proves to be an adequate tool to interpolate sparse data of the sea surface temperature robustly