This project is a co-operative action of the Meteorological Institute, University of Bonn (MIUB, Prof. Dr. Clemens Simmer), the P.P.Shirshov Institute of Oceanology, Russian Academy of Science (IORAS, Prof. Dr. Sergey Gulev), the University California at San Diego (UCSD, Dr. Alexander Gershunov), and the Odessa State Ecological University (OSEU, Dr. Sergey Ivanov). The project is focused on the quantitative description and predictability of extreme precipitation conditions over the European and American continents. This problem is of high economic and social importance for all countries, especially the ones of the proposers. The most dramatic recent Western European flood occurred in August 2002, leading to more than 100 fatalities. Economic loss amounted to 14.5 billion ˆ for Germany, Austria and the Czech Republic. High water events at major North American rivers lead to weather-associated economic looses from 2 to 6.5 billion dollars per year during the last two decades, varying tremendously year-to-year, but growing annually at approximately 200 million dollars per year. In contrast to many previous studies, which considered extreme precipitation as one of many manifestations of extreme weather, this project is directly targeted on daily extreme precipitation events in a climatic context and their seasonal prediction. In order to quantify and improve predictability of extreme precipitation events the project participants use for the first time all types of precipitation data, such as station measurements, reanalyses and model products from the leading meteorological centers and microwave radar data. The project methodology includes sophisticated statistical procedures aimed to define local precipitation extremes over Europe and North America, mesoscale modelling to investigate the physical mechanisms of atmospheric moisture transport from the oceans to the continents, and a hybrid dynamical-statistical forecasting methodology in order to predict precipitation extremes.

The main goal of this project is to quantify the major extreme weather events over the European and North American continents and their variability in order to provide quantitative predictability limits of climate extremes and to assess their potential societal impacts. In order to achieve this goal the following objectives are to be met:

• Comprehensive quantitative description of European and North American daily extremes in the context of climate over at least the last 50 years;
• Identification of the key-processes responsible for daily extreme events and understanding the mechanisms driving their interannual – decadal variability and trends;
• Assessment of the impact of climate extremes on the intensity of floods on major rivers, soil erosion, and environmental management.

These objectives are relevant to the research topics of Science for Peace Programme, such as Environmental Security, Water Resources Management, and Disaster Forecast and Prevention. Being one of the most costly natural hazards, whose intensity and frequency shows increasing trends in the changing climate, extreme rainfall and associated floods crucially affect life conditions, economy and environmental management in the highly populated Europe and North America.

Estimates of linear trends in 95% percentile of precipitation over Germany for the winter (right) and summer (left) seasons during the period from 1950 to 2003. Only significant trends are shown.

Estimates of linear trends for different classes of precipitation occurrences during the period from 1900 to 2003 for the three European locations. Red bars show the trend estimates and net shading shows the significance at 95% level.

Project participants together with Prof. W. Munk during the project meeting at UCSD (San Diego) in June 2005. From the left to the right: Pichugina, Bachner, Gershunov, Ivanov, Munk, Zveryaev, Zolina, Gulev, Simmer.