Fluck, E., Kunz, M., Geissbuehler, P., and Ritz, S. P. (2020): Radar-based assessment of hail frequency in Europe, Nat. Hazards Earth Syst. Sci. Discuss., doi:10.5194/nhess-2020-138.
In this study we present a unique 10-year climatology of severe convective storm tracks for a larger European area covering Germany, France, Belgium and Luxembourg. For the period 2005–2014, a high-resolution hail potential composite of 1 by 1 km2 is produced from two-dimensional reflectivity radar data and lightning data. Individual hailstorm tracks as well as their physical properties, such as radar reflectivity along the tracks were reconstructed for the entire time period using the Convective Cell Tracking Algorithm (CCTA2D). A sea-to-continent gradient in the number of hail days is present over the whole domain. In addition, the highest number of severe storms is found on the leeward side of low mountain ranges such as near the Massif Central in France and the Swabian Jura in southwest Germany. A latitude shift in the hail peak month is observed between the northern part of Germany where hail occurs most frequently in August, and southern France where the maximum of hail occurs two months earlier. The spatially most extended footprints with high reflectivity values occurred on 9 June 2014 and on 28 July 2013 with lengths reaching several hundreds of kilometers. Both events implied hailstones measuring up to 10 cm which caused damage in excess of 2 Billions Euros.