Journal cover Journal topic
Natural Hazards and Earth System Sciences An interactive open-access journal of the European Geosciences Union
Nat. Hazards Earth Syst. Sci., 14, 2189-2201, 2014
http://www.nat-hazards-earth-syst-sci.net/14/2189/2014/
doi:10.5194/nhess-14-2189-2014
© Author(s) 2014. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
26 Aug 2014
Medicanes in an ocean–atmosphere coupled regional climate model
N. Akhtar1,2, J. Brauch2,3, A. Dobler4, K. Béranger5, and B. Ahrens1,2 1Institute for Atmospheric and Environmental Sciences, Goethe University, Frankfurt am Main, Germany
2Biodiversity and Climate Research Center, Frankfurt am Main, Germany
3German Weather Service, Offenbach am Main, Germany
4Institute of Meteorology, Free University of Berlin, Berlin, Germany
5Unité de Mécanique, ENSTA-ParisTech, Palaiseau, France
Abstract. So-called medicanes (Mediterranean hurricanes) are meso-scale, marine, and warm-core Mediterranean cyclones that exhibit some similarities to tropical cyclones. The strong cyclonic winds associated with medicanes threaten the highly populated coastal areas around the Mediterranean basin. To reduce the risk of casualties and overall negative impacts, it is important to improve the understanding of medicanes with the use of numerical models. In this study, we employ an atmospheric limited-area model (COSMO-CLM) coupled with a one-dimensional ocean model (1-D NEMO-MED12) to simulate medicanes. The aim of this study is to assess the robustness of the coupled model in simulating these extreme events. For this purpose, 11 historical medicane events are simulated using the atmosphere-only model, COSMO-CLM, and coupled model, with different setups (horizontal atmospheric grid spacings of 0.44, 0.22, and 0.08°; with/without spectral nudging, and an ocean grid spacing of 1/12°). The results show that at high resolution, the coupled model is able to not only simulate most of medicane events but also improve the track length, core temperature, and wind speed of simulated medicanes compared to the atmosphere-only simulations. The results suggest that the coupled model is more proficient for systemic and detailed studies of historical medicane events, and that this model can be an effective tool for future projections.

Citation: Akhtar, N., Brauch, J., Dobler, A., Béranger, K., and Ahrens, B.: Medicanes in an ocean–atmosphere coupled regional climate model, Nat. Hazards Earth Syst. Sci., 14, 2189-2201, doi:10.5194/nhess-14-2189-2014, 2014.
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