Variability of the global atmospheric circulation during the past 100 years
Brönnimann, Stefan; Ewen, Tracy; Luterbacher, Jürg
In order to better understand climate variability, it is essential to address the underlying variability in the atmospheric circulation. How does the circulation interact with the ocean or land surface? How is it affected by external forcings? And what are the consequences for weather and climate? Addressing these questions is important for both seasonal-to-interannual prediction (which relies on successfully reproducing variations in the large-scale circulation) and for assessing present and future climate change (which alters atmospheric circulation). The best way to learn is by analyzing the variability of past atmospheric circulation. The past 100 years are an ideal period in this context as this period represents a range of forcings natural and anthropogenic and allows different variability timescales including extremes to be addressed. Can we document and model past atmospheric circulation variability? Do we understand the basic mechanisms that drive circulation variability on a large scale, do we understand how these mechanisms interact and do we understand how they change in a changing climate in the future? These and other questions were discussed at the meeting Variability of the global atmospheric circulation during the past 100 years that took place on Monte Verit`a near Ascona (Ticino, Switzerland) from 1520 July 2008. Seventy-five scientists from European countries and from the USA, Japan, India, and China participated in this workshop. The meeting consisted of sessions on circulation modes and midlatitude circulation, polar circulation and multidecadal modes, El Niño/Southern Oscillation teleconnections, the tropical circulation, and climate extremes. In this issue of the Meteorologische Zeitschrift, we publish selected contributions from this meeting.