@article{BuergerPfisterBronstert2021, author = {B{\"u}rger, Gerd and Pfister, Angela and Bronstert, Axel}, title = {Zunehmende Starkregenintensit{\"a}ten als Folge der Klimaerw{\"a}rmung}, series = {Hydrologie und Wasserbewirtschaftung : HyWa = Hydrology and water resources management, Germany / Hrsg.: Fachverwaltungen des Bundes und der L{\"a}nder}, volume = {65}, journal = {Hydrologie und Wasserbewirtschaftung : HyWa = Hydrology and water resources management, Germany / Hrsg.: Fachverwaltungen des Bundes und der L{\"a}nder}, number = {6}, publisher = {Bundesanst. f{\"u}r Gew{\"a}sserkunde}, address = {Koblenz}, issn = {1439-1783}, doi = {10.5675/HyWa_2021.6_1}, pages = {262 -- 271}, year = {2021}, abstract = {Extreme rainfall events of short duration in the range of hours and below are increasingly coming into focus due to the resulting damage from flash floods and also due to their possible intensification by anthropogenic climate change. The current study investigates possible trends in heavy rainfall intensities for stations from Swiss and Austrian alpine regions as well as for the Emscher-Lippe area in North Rhine-Westphalia on the basis of partly very long (> 50 years) and temporally highly resolved time series (<= 15 minutes). It becomes clear that there is an increase in extreme rainfall intensities, which can be well explained by the warming of the regional climate: the analyses of long-term trends in exceedance counts and return levels show considerable uncertainties, but are in the order of 30 \% increase per century. In addition, based on an "average" climate simulation for the 21st century, this paper describes a projection for extreme precipitation intensities at very high temporal resolution for a number of stations in the Emscher-Lippe region. A coupled spatial and temporal "downscaling" is applied, the key innovation of which is the consideration of the dependence of local rainfall intensity on air temperature. This procedure involves two steps: First, large-scale climate fields at daily resolution are statistically linked by regression to station temperature and precipitation values (spatial downscaling). In the second step, these station values are disaggregated to a temporal resolution of 10 minutes using a so-called multiplicative stochastic cascade model (MC) (temporal downscaling). The novel, temperature-sensitive variant additionally considers air temperature as an explanatory variable for precipitation intensities. Thus, the higher atmospheric moisture content expected with warming, which results from the Clausius-Clapeyron (CC) relationship, is included in the temporal downscaling.
For the statistical evaluation of the extreme short-term precipitation, the upper quantiles (99.9 \%), exceedance counts (P > 5mm), and 3-yr return levels of the <= 15-min duration step has been used. Only by adding temperature is the observed temperature observed of the extreme quantiles ("CC scaling") well reproduced. When comparing observed data and present-day simulations of the model cascade, the temperature-sensitive procedure shows consistent results. Compared to trends in recent decades, similar or even larger increases in extreme intensities are projected for the future. This is remarkable in that these appear to be driven primarily by local temperature, as the projected trends in daily precipitation values are negligible for this region.}, language = {de} } @article{RieseThiekenMueggenburgetal.2019, author = {Riese, Miriam and Thieken, Annegret and M{\"u}ggenburg, Eva and Bubeck, Philip}, title = {Synergies and barriers of the possible integration of heavy rainfall for the implementation of the European Floods Directive}, series = {Hydrologie und Wasserbewirtschaftung}, volume = {63}, journal = {Hydrologie und Wasserbewirtschaftung}, number = {4}, publisher = {Bundesanst. f{\"u}r Gew{\"a}sserkunde}, address = {Koblenz}, issn = {1439-1783}, doi = {10.5675/HyWa_2019.4_1}, pages = {193 -- 202}, year = {2019}, abstract = {The heavy rainfall events in recent years have caused great damage, which has increased the public awareness of the topic of heavy rainfall. For this reason, this article discusses how a systematic integration of heavy rainfall within the framework of the European Floods Directive would be possible and reasonable. For this purpose, a matrix covering possible synergies and barriers was created for all steps of the directive, which were then examined in 15 semi-structured interviews with representatives from specialized administration, the private sector and academia. Although there are some synergies, the additional effort required, especially regarding the identification of the risk areas and the higher level of detail required for risk modeling, would be so high that the European Floods Directive cannot be deemed to be an appropriate framework for heavy rainfall risk management. Nevertheless, there is a need for action, e.g. in the field of self-protection, improved risk communication to the population, combined with increased public and interagency cooperation.}, language = {en} } @article{JacobiHeistermann2016, author = {Jacobi, Stephan and Heistermann, Maik}, title = {Benchmarking attenuation correction procedures for six years of single-polarized C-band weather radar observations in South-West Germany}, series = {The quarterly journal of experimental psychology}, volume = {7}, journal = {The quarterly journal of experimental psychology}, publisher = {Routledge, Taylor \& Francis Group}, address = {Abingdon}, issn = {1947-5705}, doi = {10.1080/19475705.2016.1155080}, pages = {1785 -- 1799}, year = {2016}, abstract = {Rainfall-induced attenuation is a major source of underestimation for radar-based precipitation estimation at C-band. Unconstrained gate-by-gate correction procedures are known to be inherently unstable and thus not suited for unsupervised attenuation correction. In this study, we evaluate three different procedures to constrain gate-by-gate attenuation correction using reflectivity as the only input. These procedures are benchmarked against rainfall estimates from uncorrected radar data, using six years of radar observations from the single-polarized C-band radar in South-West Germany. The precipitation estimation error is obtained by comparing the radar-based estimates to rain gauge observations. All attenuation correction procedures benchmarked in this study lead to an effective improvement of precipitation estimation. The first method caps the corrections if the rain intensity increase exceeds a factor of two. The second method decreases the parameters of the attenuation correction iteratively for every radar beam calculation until attaining a stability criterion. The second method outperforms the first method and leads to a consistent distribution of path-integrated attenuation along the radar beam. As a third method, we propose a slight modification of Kraemer's approach which allows users to exert better control over attenuation correction by introducing an additional constraint that prevents unplausible corrections in cases of dramatic signal losses.}, language = {en} }