13th Martin-Schwarzbach-Colloquium

The Centre for Quaternary Science and Geoarchaeology (QSGA) is pleased to announce its 13th annual colloquium in honour of Martin Schwarzbach.
We would like to extend to you a very cordial invitation to this exciting meeting. This year, our colloquium focuses on recent advances in climate modelling.

We are especially pleased that Sharon E. Nicholson (Institute of Meteorology, Earth, Ocean & Atmospheric Science, Florida State University) and Uwe Mikolajewicz (Max Planck Institute for Meteorology, Hamburg) will present their research results.


Registration:
We kindly ask you to register by April 8th, 2019:
irtg@sfb806.de


SCHEDULE

15.00 – 15.15h:        Words of welcome

15.15 – 16.15h:        Sharon E. Nicholson
“An overview of the drivers of African climate: dispelling the myths and creating a revisionist view”  Abstract

The meteorologist’s understanding of tropical weather and climate has changed dramatically over the last few decades. Nowhere have the changes been greater than over Africa. Many things are still not well understood, including simple questions about the seasonal cycle. Progress in understanding African climate has been hindered by several myths that have been widely accepted. Several of these are discussed in this talk. The main focus, however, is on major changes in our understanding of African climate. These are relevant for paleoclimate studies that strive to produce a meteorological interpretation of findings. A very important change is the question of the ITCZ paradigm for producing the seasonal cycle and modulating interannual variability. This paradigm has numerous shortcomings. Moreover, an historical look at the concept shows that its use over Africa has long been controversial, with many eminent tropical meteorologists harshly criticizing its applicability over this continent. Related to this is the recognition of the importance of mesoscale convective systems and tropical/extra-tropical hybrid systems in production rainfall over Africa. A second major change is recognizing the important role of jet streams and regional circulation systems in governing rainfall variability. Related to this is the inappropriate application of global concepts on a regional basis. A third change is the realization that many teleconnections, such as those to El Niño, are transient in nature. These ideas have greatly improved our understanding of climate variability over Africa but much still remains to be done.

16.15 – 16.30h:        Coffee Break

16.45 – 17.45h:        Uwe Mikolajewicz
“Simulating the late glacial and the deglaciation with a comprehensive climate model”  Abstract

 

Paleo proxy data indicate strong and rapid climate changes (e.g. Heinrich events or the Younger Dryas cold spell) during the last deglaciation. Here modelling could be very helpful for the interpretation of the proxy data, but the models are not really suited for the simulation of these long time periods, as the boundary conditions (e.g. topography and land sea masks) should not be treated as constant anymore.

A new developed model system consisting of the atmosphere model ECHAM, the ocean model MPIOM, the ice sheet model PISM and the solid earth model VILMA (important for glacial isostatic adjustment) with automatic adaptation of land-sea mask, ocean bathymetry, land orography and river routing designed for long-term simulations is currently in the test phase.

Here results are presented from simulations with different subsystems focussing on the deglaciation. It is shown, that changes in river routing due to retreating ice sheets can explain the occurrence of an abrupt cold event due to a strong reduction of the Atlantic heat transport. Changes in the land-sea mask turned out to be important as well, especially for the late phase of the last deglaciation.

Another focus of the presentation are mechanisms of millennial scale climate variability during the Glacial. In a coupled atmosphere-ocean-northern hemisphere ice sheet model Heinrich events occurred as internal variability. In certain parameter ranges, an atmosphere-ocean model showed long-term fluctuations of the Atlantic overturning which signatures remind of Dansgaard-Oeschger events. The model simulations allow to investigate the underlying mechanisms.

17.30h:                     Farewell drinks and snacks


Venue:

Geo-/Bio-Hörsaal
Zülpicher Straße 49, Building 310c

Directions:
Köln-Süd (train)
Dasselstr./Bf.Süd (tram line 9)