The INTEXseas project has been funded by the European Research Council as an ERC advanced grant, awarded to Prof. Dr. Heini Wernli. In this project we introduce extreme seasons as a new concept in weather and climate research. Examples are the coldest winter, the wettest summer, or the windiest autumn in a particular region. Investigating the characteristics and underlying dynamical processes of extreme seasons, and how, where and why they change with global warming is scientifically challenging, of high socioeconomic relevance, and a novel aspect of weather and climate research.

The main overall objectives of the INTEXseas project are to:

1. Identify a large set of extreme seasons using state-of-the-art reanalyses and global ensemble climate model simulations.
2. Provide a detailed statistical and weather-system based characterization of extreme seasons in the present climate.
3. Quantify differences in extreme season characteristics in the future relative to the present-day climate, and identify the reasons.
4. Relate the characteristics of different types of extreme seasons to selected theoretical concepts of the atmospheric general circulation (in particular storm track dynamics and concepts of cloud-dynamics interactions).
5. Assess the characteristics of a selection of “impact-related” extreme seasons today and in a warming climate. As outlined below, the selected types of extremes are related to snow-dependent Alpine winter tourism; consequences of frost for viniculture in different parts of the world; extreme seasonal anomalies for the production of renewable energy; and the insurance impact of storm clustering.