Regional analysis of convective heavy rain events in the German State of Hesse

The convective heavy precipitation events, which occur primarily in the summer months, cannot be recorded representatively by ground-based precipitation stations due to their frequently small spatial extent, short life span and high rapidly changing intensity. The radar network of the German Weather Service, on the other hand, records area-wide, spatiotemporally highly resolved precipitation information that enables comprehensive identification of precipitation objects. In this study, a method for the identification, description and classification of convective precipitation objects considering a flood-relevant event extent is presented. Assuming an orographic independence of the events in the Central European low mountain range, the German State of Hesse is chosen as representative study area. Considering the spatial and temporal extent of the identified events, the most extreme expression is selected and independence is ensured. With the assignment of an authoritative duration for the intensive main rainfall phase, an extensive collection of heavy precipitation objects results. The results show a characteristic event length of 15 to 60 minutes; longer durations are underrepresented and exhibit inhomogeneous extreme value behavior. Statistically, the generated samples can be well represented and classified by the generalized extreme value distribution. The evaluation allows us to make a regional characterization of convective heavy precipitation.