Short-term Climate Variability and Teleconnections

Large-scale flow variations are an integral feature of the climate system and exhibit substantial fluctuations on decadal and inter-annual time scales: e.g. the prominent tropical ENSO phenomenon, the extra-tropical PNA pattern and the North-Atlantic Oscillation (NAO). There is a clear linkage of the variability patterns with distinctive climatic and synoptic weather phenomena (North Atlantic storm track, patterns of underlying SST and flow variations over Europe - e.g. temperature and precipitation). Less is known about the origin and dynamics of these modes. Complementary approaches comprising statistical and observational studies, and idealised and climate model simulations are applied to gain insight into the underlying physical processes and analyse the structure, time-evolution and impacts of these large-scale phenomena.

• dynamical and climatological aspects of atmospheric blockings  (Mischa Croci-Maspoli)
• blocking relation to large-scale climate modes (Mischa Croci-Maspoli)
• life-cycle of PV-filaments (Olivia Martius)
• synoptic scale Rossby-wave propagation and precursors (Olivia Martius)
• interaction between breaking synoptic scale Rossby-waves and blocking (Olivia Martius, Mischa Croci-Maspoli and Adrian Altenhoff)
• NCCR Climate Swiss National Centre for Competence in Research, Project 2.3a (Short-term climate variability: Dynamics and Processes) (Conny Schwierz, Olivia Martius and Mischa Croci-Maspoli)
• Stationary Rossby wave propagation is supposed to play a key role (e.g. Simmons et al., 1983) in the setup of the well known teleconnection patterns (following Wallace and Gutzler, 1981) like the PNA, Western Atlantic and Eurasian Pattern. So far the main focus has been on barotropic Rossby waves emerging out of the tropical Indo-Pacific region, forced by upper level divergence or heating. Here the focus will be on baroclinic development initiated by such forcings via interaction of the Rossby waves with the midlatitude jet-streams. Especially for the Atlantic region the direct influence of Rossby waves initiated in the tropics is thought to play a minor role or indirect effect on the established patterns evident. In contrast to some earlier barotropic studies the three dimensional global ECMWF model is utilized here. (Thomas Spengler)

• Concluded research