InterDec is an international initiative aiming at understanding the origin of decadal-scale climate variability in different regions of the world and the linkages between them by using observational data sets and through coordinated multi-model experiments. The understanding and skilful prediction of decadal-scale climate variability that modulates the regional occurrence of extreme weather events will be of enormous societal and economic benefit.
Societies are vulnerable to weather and climate extremes by setting agriculture and infrastructure at risk, increasing the risk for forest fires or causing health problems. Systematic analysis of inter-regional linkages between Arctic, mid-latitudes and Tropics will lead to a better understanding of extreme events such as monsoon breaks and intensifications, Eurasian mid-latitude cold spells and heat waves or rapid declines in Arctic sea ice. Identifying key regions driving decadal-scale variations can lead to more reliable decadal predictions, which in turn can improve disaster prevention and mitigation strategies, especially in densely populated area.
The heart of InterDec are coordinated multi-model ensemble sensitivity experiments with a hierarchy of state-of-art climate models, which allow to explicitly extract the climate response to a specific perturbation in a particular region. This is inevitable in order to understand the importance of individual regions for Arctic-Mid-latitude-Tropics linkages and deconstruct the physical processes behind these linkages. Such knowledge cannot be obtained from solely analysing existing simulations such as CMIP5, CMIP6 or PRIMAVERA nor from observations, which do not provide consistent sets of atmospheric and oceanic parameters without temporal and spatial gaps. The coordinated multi-model approach is crucial for assessing the robustness of the results and quantifying uncertainty.
The main objective of InterDec is to improve our understanding of the inter-linkages among sub-seasonal to decadal climate variability in the Arctic, Mid-latitudes and Tropics, their mechanisms and potential for predictions. Sub-objectives are:
- To investigate the mechanisms that govern the fast atmospheric linkages through both tropospheric and stratospheric processes between polar and lower latitudes and explore the potential for predictions on sub-seasonal to seasonal time scales.
- To advance our understanding of how the frequency and amplitude of extreme weather events can be modulated by decadal-multidecadal changes in the background climate conditions.
- To explore the role of the ocean for low frequency signal communication between high and low latitudes and the implications for decadal predictability.
- To explore the added value of increased climate model resolution for a more realistic representation of the processes linking high and low latitudes and for enhancing the predictability of high-impact climate and extreme weather events on regional scales.
- To share the improved knowledge on the occurrence of extreme climate events on sub-seasonal to decadal scales with Climate Service Centers and stakeholders.
Role of SMHI
In InterDec, SMHI is leading Task 6 - Quantify the role of Subpolar North Atlantic Gyre (SPG) and MOC in linking polar and lower latitudes. This task aims by investigating existing observational and modelling data sets:
- to investigate the impact of temperature variations in the subpolar gyre and of the recently observed and forecasted cooling trend (“North Atlantic cold blob”) on European climate and probability for extreme precipitation events, droughts, heat waves and cold spells.
- to analyze the role of the AMOC for African monsoon frequency and precipitation.
- to improve understanding of mechanisms affecting variations in the SPG, AMOC andtheir feedback on Arctic.
- to investigate the role of model biases in North Atlantic SST and Arctic SIC, and of highresolution in impacting the realism of simulated oceanic-driven linkages.
In addition, SMHI will participate in coordinated modelling experiments to further investigate the linkage between Arctic sea ice and lower latitudes.
InterDec is coordinated by Daniela Matei (Max-Planck-Institut für Meteorologie) and includes partners from 4 European countries, China and Japan. The complete list of partners can be found.
InterDec is funded by the Belmont Forum and JPI Climate (sponsors: NSFC, BMBF, JST, RCN, FORMAS, NERC).
InterDec will run from 2016 to 2019.