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Advances in Meteorology
Volume 2014 (2014), Article ID 427916, 11 pages
Research Article

Analysis and Discussion of Atmospheric Precursor of European Heat Summers

1Deutscher Wetterdienst, Frankfurter Straße 135, 63067 Offenbach am Main, Germany
2Laboratory for Climatology and Remote Sensing, Department of Geography, Philipps University, Deutschhausstraße 10, 35032 Marburg, Germany

Received 4 September 2014; Accepted 6 October 2014; Published 24 November 2014

Academic Editor: Gwo-Fong Lin

Copyright © 2014 Christine Träger-Chatterjee et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The prediction of summers with notable droughts and heatwaves on the seasonal scale is challenging, especially in extratropical regions, since their development is not yet fully understood. Thus, monitoring and analysis of such summers are important tasks to close this knowledge gap. In a previous paper, the authors presented hints that extreme summers are connected with specific conditions during the winter-spring transition season. Here, these findings are further discussed and analysed in the context of the Earth’s circulation systems. No evidence for a connection between the North Atlantic Oscillation or the Arctic Oscillation during the winter-spring transition and extremely hot and dry summers is found. However, inspection of the geopotential at 850 hPa shows that a Greenland-North Sea-Dipole is connected with extreme summers in Central Europe. This motivated the introduction of the novel Greenland-North Sea-Dipole-Index, GNDI. However, using this index as predictor would lead to one false alarm and one missed event in the time series analysed (1958–2011). Hints are found that the disturbance of the “dipole-summer” connection is due to El Niño/Southern Oscillation (ENSO). To consider the ENSO effect, the novel Central European Drought Index (CEDI) has been developed, which is composed of the GNDI and the Bivariate ENSO Time Series Index. The CEDI enables a correct indication of all extremely hot and dry summers between 1958 and 2011 without any false alarm.