Changing North Atlantic variability under global warming

• Main Author: Jungclaus, Johann
• Format: Lecture
• Language: unknown
• Published: Zenodo 2019
• Subjects: North Atlantic; North Atlantic oscillation
• Online Access: https://doi.org/10.5281/zenodo.3241436

The climate in the North Atlantic and its surrounding continents is expected to change considerably under global warming with specific regional characteristics. For example, the Atlantic Meridional Overturning Circulation is expected to slow down under global warming, which will leave an imprint in surface properties, such as sea-surface temperature patterns. Moreover, increasing greenhouses gas forcing may not only lead to changes in the mean state of the ocean but also to variations in the characteristics of internally-generated variability, to rapid transitions from one preferred state to another, and to modifications in tele-connections. Here we use a novel large ensemble of historical and scenario simulations carried out with the MPI-ESM to investigate how variability changes over time. The large number of ensemble members (100) allows us to better understand the role of internal variability by assessing the variance across the ensemble dimension. In addition, a large ensemble enables more robust estimates of spectral characteristics and boosts confidence in spectral peaks. We present an evaluation of variability changes in frequency space for different timescales and provide analyses of evolving relationships between the variability of climate indices (e.g. the North Atlantic Oscillation) and regional climate variability.