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www.clim-past-discuss.net/7/1457/2011/
doi:10.5194/cpd-7-1457-2011
© Author(s) 2011. This work is distributed
under the Creative Commons Attribution 3.0 License.
Upper ocean climate of the Eastern Mediterranean Sea during the Holocene Insolation Maximum – a model study
1Max Planck Institute for Meteorology, Hamburg, Germany
2International Max Planck Research School on Earth System Modelling, Hamburg, Germany
3Univ Tübingen, Department of Geosciences, Tübingen, Germany
4Department of Geosciences, University of Hamburg, Hamburg, Germany
5Univ Hamburg, Inst Biogeochem and Marine Chem, Hamburg, Germany
Abstract. Nine thousand years ago, the Northern Hemisphere experienced enhanced seasonality caused by an orbital configuration with a minimum of the precession index. To assess the impact of the "Holocene Insolation Maximum" (HIM) on the Mediterranean Sea, we use a regional ocean general circulation model forced by atmospheric input derived from global simulations. A stronger seasonal cycle is simulated in the model, which shows a relatively homogeneous winter cooling and a summer warming with well-defined spatial patterns, in particular a subsurface warming in the Cretan and Western Levantine areas.
The comparison between the SST simulated for the HIM and the reconstructions from planktonic foraminifera transfer functions shows a poor agreement, especially for summer, when the vertical temperature gradient is strong. However, a reinterpretation of the reconstructions is proposed, to consider the conditions throughout the upper water column. Such a depth-integrated approach accounts for the vertical range of preferred habitat depths of the foraminifera used for the reconstructions and strongly improves the agreement between modelled and reconstructed temperature signal. The subsurface warming is recorded by both model and proxies, with a light shift to the south in the model results.
The mechanisms responsible for the peculiar subsurface pattern are found to be a combination of enhanced downwelling and wind mixing due to strengthened Etesian winds, and enhanced thermal forcing due to the stronger summer insolation in the Northern Hemisphere. Together, these processes induce a stronger heat transfer from the surface to the subsurface during late summer in the Western Levantine; this leads to an enhanced heat piracy in this region.
Discussion Paper (PDF, 8008 KB) Interactive Discussion (Closed, 7 Comments) Final Revised Paper (CP)
Notice on Discussion StatusCitation: Adloff, F., Mikolajewicz, U., Kucera, M., Grimm, R., Maier-Reimer, E., Schmiedl, G., and Emeis, K.: Upper ocean climate of the Eastern Mediterranean Sea during the Holocene Insolation Maximum – a model study, Clim. Past Discuss., 7, 1457-1509, doi:10.5194/cpd-7-1457-2011, 2011. Bibtex EndNote Reference Manager XML
