MEDEVAC: Mechanisms of multi-Decadal Variability in the Climate system
What are the goals of the project?
In the MEDEVAC-project we analyse state-of-the-art climate models simulations and high-resolution paleoclimate reconstructions to study and better characterise the mechanisms of climate variability on a decadal to centennial scale. It is particularly exciting to find out what sea-shells can teach us about paleoclimates. Sea-shells can be considered the ‘tree-rings of the ocean’, and can give us climate information back in time on seasonal to annual time scales, compared to sediment cores which are only able to provide information on a 5 to 10 year scale. The project is a continuation of the previous SKD-project IMMUNITY and one particular goal of MEDEVAC is to assess the relative role of poleward atmospheric and oceanic heat transport and their coupling through the so-called Bjerknes compensation mechanism.
What are the main results so far?
At this point, atmospheric and oceanic heat transports in NorESM have been calculated and analysed, and as expected we found a peak anti-correlation in the high latitudes. There is also a slightly higher peak that occurs at around 40N, likely related to the North Atlantic storm tracks. Several researchers from the project have also published a paper investigating the relationship between changes in the water that overflows through the Faroe Shetland Channel and downstream bottom velocity south of Iceland at the so called Gardar Drift, using a combination of paleo proxy reconstructions and simulations with the Bergen Climate Model.
What are the future plans?
We have established a chronology through investigating the sea-shells, and the next step is to conduct comprehensive chemical analyses of the shells, and compare the data to available historical model simulations for the last millennium. In order to investigate various aspects of the atmosphere-ocean coupling involved in multidecadal variability several model sensitivity experiments using NorESM are planned later in 2016. Furthermore, additional analyses of historical CMIP5 model runs will help establish the robustness of the Bjerknes compensation mechanism across different model platforms. Finally, potential mechanisms of long-term variations in rainfall variability will be explored, with a particular focus on the East Asian monsoon, in close collaboration with colleagues at the Nansen-Zhu Centre in Beijing, China.
Who is involved?
NERSC: Stephen Outten, Helene Langehaug, Igor Esau, Yongqi Gao
UiB: Jostein Bakke, Johannes Werner, Torgeir Røthe, Helga F. Kleiven, Ulysses Ninnemann, Harald Sodemann, Nour-Eddine Omrani, Astrid Kristine Fremme
Uni Research: Odd Helge Otterå, Carin A. Dahl, Thomas Toniazzo, Trond Dokken, Fabian Bonitz
Duration: 2015 - 2017
The project is closely linked with the ARAMACC network (Annually Resolved Archives of Marine Climate Change). Several researchers attended the ARAMACC Summer School 2# in Split, Croatia 9 -13th of May, 2016.