In Europe, thunderstorms are increasingly recognized as an important hazard to life and property. According to the Munich Re Group, a yearly total damage of about € 5 billion (Munich Re Group, 2006) is inflicted by thunderstorm-related severe weather events (hail, flash floods, straight-line winds, tornadoes, and lightning) in Europe. Yet, relatively little is known about what effects climate change has on the frequency and intensity of these localized and short lived hazards.
The spatial and temporal resolution of global as well as regional models is insufficient to simulate thunderstorms and their attendant hazardous phenomena. Yet these models do contain information related to the occurrence of these events. Within STEPCLIM a method is developed that will allow climate models to be used for the prediction of the frequency and intensity of hail, tornadoes, severe wind gusts and extreme rainfall in the future.
The development of this method requires that quality-controlled datasets of severe weather occurrence be available. To that aim, STEPCLIM will first evaluate the quality of two of such datasets, to wit the European Severe Weather Database (ESWD) and Storm Data. Subsequently, the dataset managed by ESSL (ESWD) will be further optimized for use in further analyses within the project.
Secondly, a first range of metrics will be developed by relating severe weather observations with reanalysis datasets, i.e. data that represents the past weather. Third, these metrics will be calibrated by applying them to both global and regional datasets of the past climate (so-called hindcasts). This procedure will be repeated in the final phase of the project, using the improved ESWD dataset and the improved MiKlip system for decadal climate prediction.
Finally, the predictability of thunderstorm-related weather hazards using the MiKlip system will be assessed. After a final calibration of the metrics, these, and the software to compute them, will be integrated into the MiKlip system.
STEPCLIM will be conducted by the European Severe Storms Laboratory seated in Wessling, Germany.