EGU General Assembly 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Atmosphere-mediated response of the Southern Hemisphere hydroclimate in simulations of spontaneous Dansgaard-Oeschger-like oscillations

Irene Trombini1, Nils Weitzel1,2, Muriel Racky1, Paul Valdes3, and Kira Rehfeld1,2,4
Irene Trombini et al.
  • 1Institute of Environmental Physics, Heidelberg University, Heidelberg, Germany
  • 2Department of Geosciences, University of Tübingen, Tübingen, Germany
  • 3School of Geographical Sciences, University of Bristol, Bristol, United Kingdom of Great Britain – England, Scotland, Wales
  • 4Department of Physics, University of Tübingen, Tübingen, Germany

Dansgaard-Oeschger (DO) events are the most iconic mode of millennial-scale variability during the last glacial period. The manifestation of DO events outside the North Atlantic region and mechanisms responsible for the propagation of the North Atlantic signal across the globe are still little understood. Propagation of DO events to the Southern Hemisphere (SH) has first been explained by oceanic processes, that result in a muted and delayed signal in the Antarctic ice core record, known as Antarctic Isotope Maxima (AIM). Recent ice core-based reconstructions found an additional short-timescale response (years-to-decades, compared to centuries for the oceanic processes) in phase with the climate changes in Greenland. This fast response has been interpreted as the result of atmospheric transport processes. Shifts in the intertropical convergence zone and SH mid-latitude westerlies are seen as mediators of this response.

Here, we investigate the propagation of abrupt climate changes in the North Atlantic region to the SH in general circulation model simulations with spontaneous DO-like oscillations under glacial conditions. We study the relative timing of changes in temperature, hydroclimate, and atmospheric circulation and compare our results with ice core and speleothem based reconstructions. In the simulations, the timing of changes in different elements of the climate system varies on a continuum of timescales from months to centuries. This indicates the existence of more complex propagation mechanisms than the simple separation into an atmospheric and an oceanic mode. Our work emphasizes that future analysis of simulations of DO-like events should focus not just on the mechanisms responsible for the spontaneous oscillations but also on the spatio-temporal fingerprint of the oscillations across the globe.

How to cite: Trombini, I., Weitzel, N., Racky, M., Valdes, P., and Rehfeld, K.: Atmosphere-mediated response of the Southern Hemisphere hydroclimate in simulations of spontaneous Dansgaard-Oeschger-like oscillations, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-2885,, 2023.