R&D highlights edition 2019

PROJECTS Enabling technologies P arametric wind profiles are commonly applied in a number of engineering applications for the generation of tropical cyclone (TC) wind and pressure fields. Nevertheless, existing formulations for computing wind fields often lack the required accuracy when the TC geometry is not known. This may affect the accuracy of the computed impacts generated by these winds. This study derives empirical stochastic relationships based on satellite information to describe two important parameters affecting the TC geometry: radius of maximum winds (RMW) and the radius of gale force winds (∆AR35). These relationships are formulated using best-track data (BTD) for all seven ocean basins (the Atlantic, Pacific and Indian Oceans), making it possible to a) estimate RMW and ∆AR35 when these properties are not known and b) generate improved parametric wind fields for all ocean basins. Validation results have shown how the proposed relationships allow the TC geometry to be represented with higher accuracy than when using relationships available from the literature. Outer wind speeds can be well reproduced with the commonly used Holland wind profile when calibrated using information from either best-track data or the proposed relationships. The scripts for computing the TC geometry and the outer wind speed are freely available via Delft Dashboard. Contact: Kees Nederhoff, Kees.Nederhoff@deltares.nl, t +31 (0)6 15820403 Alessio Giardino, Alessio.Giardino@deltares.nl, t +31 (0)6 15821874 Parametric wind profiles are commonly applied for the generation of tropical cyclone (TC) wind fields. This study derives empirical stochastic relationships to describe TC geometry. Validation results have shown how the proposed relationships allow the TC geometry to be represented more accurately than when using relationships available from the literature. IMPROVEMENT OF HAZARD AND DAMAGE ESTIMATIONS FOR TROPICAL CYCLONES USING SATELLITE DATA Scatter plot describing ∆AR35 (BTD and predicted) as a function of the maximum sustained wind speeds (and the latitude; not shown). The blue line is the median of the proposed relationship derived for all basins at an arbitrarily chosen latitude of 10°. The green line is the median of the BTD. The red area shows the 90 percent prediction interval based on the proposed relationship for the standard deviation. The 5 and 95 percent exceedance values from the BTD are presented as black solid lines. Gray dots are observation points. More frequent observations are shown as darker points. Wind speed error profiles from different models versus observations fromQuikSCAT as a function of r / RMW. A value equal to zero indicates a perfect match between the model and observations. Interquartile ranges are shown with filled colours. Note: the most probable value for RMW and AR35 was used for the proposed relationships (i.e. mode). 60