Performance of storm damage functions: a sectoral impact model intercomparison

Abstract

Winter storms are the most costly natural hazard for European residential property. We compare four distinct storm damage functions with respect to their forecast accuracy and variability, with particular regard to the most severe winter storms. The analysis focuses on daily loss estimates under differing spatial aggregation, ranging from district to country level. We discuss the broad and heavily skewed distribution of insured losses posing difficulties on both the calibration and the evaluation of damage functions. From theoretical considerations, we provide a synthesis between the frequently discussed cubic damage-wind relationship and recent studies that report much steeper damage functions for European winter storms. The performance of the storm loss models is evaluated for two wind data sources, direct observation by the German Weather Service and ERA Interim reanalysis data. While the choice of wind data indicates little impact for the evaluation of German storm loss, local variability exhibits dependence between model and data choices. Based on our analysis, we favour the application of two probabilistic approaches which fare best in terms of the accuracy of their expected value and overall exhibit the lowest amount of variability.