Project

Discipline

Hail and Lightning observations; Climate change; Severe convective storms; Convection-resolving simulations

Lead
Wie verändern sich schwere Gewitter mit dem Klimawandel? Wie können hochauflösende Klimamodelle dazu beitragen, die Anpassung an den Klimawandel voranzutreiben?
Lay summary
Schwere Gewitter – oft verbunden mit Hagel, Blitzschlag, Starkniederschlägen, Überschwemmungen und Windböen – fordern oft Menschenleben und verursachen jedes Jahr enorme ökonomische Schäden. Obwohl das Verhalten von schweren Gewittersystemen in den Grundzügen verstanden ist, stellen Gewitter gewaltige Herausforderungen an Praxis und Wissenschaft. Einerseits sind Beobachtungen von Gewittern oft unvollständig und sporadisch. Andererseits lassen sich Gewitter in konventionellen Klimamodellen aufgrund ihrer kleinräumigen Struktur nicht simulieren. Das vorliegende Projekt dient der Erforschung solcher Ereignisse im Grossraum der Alpen auf Zeitskalen von Jahrzehnten bis Jahrhunderten. Zu diesem Zweck sollen hochauflösende Klimamodelle eingesetzt werden, welche moderne Hardware-Architekturen optimal nutzen. Zur Überprüfung und Weiterentwicklung der Modelle werden umfangreiche  Beobachtungsdaten verwendet, darunter auch Daten eines aussergewöhnlich dichten Netzwerks von Hagel-Detektoren in Kroatien. Mit hochauflösenden Klimamodellen soll insbesondere auch untersucht werden, wie sich die Häufigkeit und der Charakter solcher Unwetter mit dem Klimawandel verändert. Das Projekt beinhaltet eine enge Zusammenarbeit mit zwei kroatischen Forschungsgruppen. Die Resultate sollen helfen, die Anpassung an den Klimawandel voranzutreiben und zu optimieren.

Direct link to Lay Summary

Last update: 08.02.2019

Active participation

Number	Title	Start	Funding scheme

Severe convective storms are a primary cause of catastrophic loss through property damage and life-threatening weather conditions. These events are characterized by the presence of heavy convective storms, lightning that can initiate wildfires, strong and damaging winds (e.g., wind gusts), as well as heavy rain that can cause flash floods and hail. Due to sparse observations and inability of conventional climate models to represent these local weather phenomena, our understanding of severe weather events and their response to a changing climate is still very limited. Advances in computational power and recent developments in atmospheric modeling have enabled the use of climate models at kilometer-scale horizontal resolutions. These so-called convection-resolving models (CRMs) resolve deep convective events such as thunderstorms and rain showers. Such models have been used for numerical weather forecasting purposes for over a decade. Although these models improve the simulation of heavy precipitation, their application for climate studies and the analysis of severe convective events, like lightning, hail and severe winds, has been very limited. The proposed collaboration will investigate severe weather events over Europe, with a specific focus on the Alpine and Adriatic region. The main goals of the study are to better understand severe weather events, to evaluate their representation in weather and climate models, and to investigate their response to climate change. Key elements of the proposal are: The exploitation of a unique Croatian hail-pad data set, the exploration and intercomparison of a wide range of different atmospheric (weather and climate) modeling systems, and the use of kilometer-scale pan-European decade-long simulations using the first regional climate modeling framework able to run entirely on Graphics Processing Units (COSMO-GPU).The SWALDRIC project is organized into three parts, which will be addressed through three PhD projects that will focus on the analysis and climatology of observational data, performing, intercompare and validate high-resolution case study simulations using hail and lightning diagnostics, and conduct and analyze decade-long European-scale climate simulations at 2 km resolution. The collaboration of Croatian and Swiss scientists in SWALDRIC is essential for achieving the project goals, and will include sharing model components, model data, observations, experience in using severe weather diagnostics, and exchange of knowledge. The project will not only deepen the collaboration of Swiss and Croatian scientists, but will also contribute to the general understanding of severe weather events, and their response to the further warming and moistening of the atmosphere. This will be the first time that climate changes of severe weather events will be addressed in such high-resolution simulations over pan-European scales.