Eberhard Faust

Structural variation in genesis and landfall locations of North Atlantic tropical cyclones related to SST

The influence of sea surface temperature on the locations of the genesis and of landfall of tropical cyclones in the North Atlantic is analyzed. For that purpose, these locations are calculated from HURDAT and split into two disjoint subsets according to whether sea surface temperature in the North Atlantic was above or below average in the year the corresponding storms occurred. Landfalls are investigated separately for the groups of cyclones categorized as tropical storms, minor hurricanes, or major hurricanes at the moment of landfall. The locations are considered realizations of inhomogeneous Poisson point processes, and the corresponding density functions are estimated with kernel estimation methods. In this way, any spatial structure inherent in the data is taken into account. These density functions are then compared with Monte Carlo methods from spatial statistics, which allows the detection of areas of statistically significant differences in the two sets with high and low SST, respectively. Results show many such areas, which is of relevance for the insurance industry and mathematical modelling of cyclones, as well as for decision support during the preparation for natural disasters.

Detecting Severe Weather Trends Using an Additive Regressive Convective Hazard Model (AR-CHaMo)

AbstractA statistical model for the occurrence of convective hazards was developed and applied to reanalysis data to detect multi-decadal trends in hazard frequency. The modeling framework is based on an additive logistic regression of observed hazards to predictors derived from numerical model data. The regression predicts the probability for a severe hazard, which is considered as product of two components: the probability that a storm occurs and the probability of the severe hazard given the presence of a storm: P(severe) = P(storm) x P(severe|storm). The model was developed using lightning data as an indication for thunderstorm occurrence and hazard reports across Central Europe. Although it uses only two predictors per component, it is capable of reproducing the observed spatial distribution of lightning and yields realistic annual cycles of lightning, hail and wind fairly accurately. The model was applied to the ERA-Interim reanalysis (1979 - 2016) across Europe to detect any changes in lightning, h...