Joint Seminar: Glacial times - from hemispheric climate response to Alpine impacts

The aim of this study to assess the impact of orbital forcing and northern hemispheric ice sheet height variations on atmospheric dynamics such as stationary waves and extratropical cyclones during winter. In a second step we assess how these changes translate to regional scales such as the Alpine region, which help to better simulate small ice caps such as the Alpine ice sheet.

The main research tools are the Community Earth System Model CESM and the Weather Research and Forecasting model WRF. We performed a set of time slice sensitivity simulations under preindustrial (PI) conditions and for the following different glacial periods: Last Glacial Maximum (LGM), Marine Isotopic stage 4 (MIS4), MIS6, and MIS8. Additionally, we vary the northern hemispheric ice sheet height for all the different glacial periods by 33%, 66%, 100% and 125% of the ice sheet reconstructed for the LGM. Most of these simulations are dynamically downscaled to convection permitting scales of 2 km over the Alpine region.

Results show that the stationary waves as well as extratropical cyclone tracks are affected by both orbital changes and ice sheet height changes. These changes cannot be easily superimposed, so that the non-linearity needs to be considered.  The regional downscaling shows a clear gain with respect to precipitation which substantially improved the simulation of the Alpine ice cap during glacial periods such as the Last Glacial Maximum.




13:30 Uhr


Bundesstr. 53, room 022/023
Seminar Room 022/023, Ground Floor, Bundesstrasse 53, 20146 Hamburg, Hamburg


Uwe Mikolajewicz

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