PhD defence by Ivana Cvijanovic, Centre for Ice and Climate – Niels Bohr Institute - University of Copenhagen

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PhD defence by Ivana Cvijanovic, Centre for Ice and Climate

Abrupt climate change and high to low latitude teleconnections as simulated in climate models

High to low latitude atmospheric teleconnections have been a topic of increasing scientific interest since it was shown that high latitude extratropical forcing can induce tropical precipitation shifts through atmosphere-surface ocean interactions. In this thesis, several aspects of high to low latitude atmospheric teleconnections have been considered.

The atmospheric energy transport response during Northern Hemisphere cooling and warming is investigated using sea surface temperature (SST) anomalies derived from a freshwater hosing experiment. The results showed the enhanced sensitivity of the present day atmospheric mid-latitude energy transport compared to that of the Last Glacial Maximum, suggesting its ability to reorganize more easily and thereby dampen high latitude temperature anomalies that could arise from changes in the oceanic transport.

The role of tropical SSTs in the tropical precipitation shifts was further re-examined in idealized simulations with the fixed tropical sea surface temperatures, showing that the SST changes are fundamental to the tropical precipitation shifts. Regarding the high latitude energy loss, it was shown that the main energy compensation comes from the southern tropics, with the energy gain originating from the cloud radiative feedbacks, temperature and longwave water vapor feedbacks.

Extended consideration of the various scenarios that can induce the southward precipitation shifts showed that the Southern Hemisphere warming simulations, in addition to causing the ITCZ shifts, can also affect the high northern latitudes, as seen from the surface temperature and wind strength changes. These results may have important paleo implications to the Dansgaard-Oeschger type of events.

If interested please contact Ivana Cvijanovic for a copy of the thesis (ivanacv @