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Institute of Energy and Climate Research

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YIRG Modelling of climate-relevant processes

Climate variations on inter-annual to decadal time scales can greatly exceed climate change predictions based on steadily rising greenhouse gas levels, and may severely impact ecosystems and society. However, owing to the complexity of processes involved, decadal climate variations are inadequately captured in current climate models, and decadal predictions are largely uncertain. Recent analyses indicate a crucial impact of variations in the composition of radiatively active trace gas species (water vapor and ozone) in the stratosphere (the atmosphere between 10-50km altitude) on the Earth's radiation budget and on surface climate. However, the processes controlling decadal variability in stratospheric composition are not well known and thus inadequately represented in models.

In the Helmholtz Young Investigators Group „Modelling of climate-relevant processes“ we investigate key processes for variability in the trace gas composition of the stratosphere on interannual to decadal time scales, and assess their impact on climate variability. Such key processes comprise the global stratospheric Brewer-Dobson circulation, and stratosphere-troposphere exchange processes like in the Asian monsoon. Close collaboration exists with the theory-group at the IEK-7. For our research, we use the Lagrangian transport modell CLaMS (developed within the theory group) coupled with the climate model EMAC. Our method combines high-resolution airborne in-situ trace gas measurements and detailed process modelling with global satellite observations, global climate modelling, and sophisticated transport diagnostics (in particular age of air) and bridges the gap between the sparse but high-quality measurements and global scale climate impacts.

Our research focus lies on:

  • Investigation of medium-term (inter-annual to decadal) changes of the global stratospheric Brewer-Dobson circulation, as well as stratosphere-troposphere exchange processes (e.g., Asian monsoon)
  • Quantification of medium-term changes in the stratospheric trace gas composition (e.g., water vapor, ozone)
  • Assessment of the induced climate effects
  • Development of the model system EMAC-CLaMS to realize Lagrangian trace gas transport (CLaMS) in a global climate model (EMAC)