Tropical Cyclone Statistical Wind Estimation

Abstract

Tropical Cyclones (TCs) are in many regions responsible for severe damages and a great number of casualties, resulting from the severe wind speeds, rainfall, wave heights and storm surges. The recent hurricanes Harvey and Irma are examples of the great devastation that can be caused by a single event, and of the insufficient level of preparedness that is currently present to withstand the adverse effects of such an event. Even in the U.S., which suffers relatively frequently from TCs, and has an extensive track record of historical events, the consequences of Harvey were unforeseen and destructive. Difficulties in determining extreme TC conditions, whether these are rain, wind, wave or storm surge conditions, mostly come from the fact that severe adverse effects caused by TCs are very local. This is the case because the exact track, intensity and size of the storm determine to a large extent which area is affected the most, and what the consequences are for the hydraulic conditions. Small variations in any of these parameters can greatly influence the conditions at any location. This is already the case in regions which suffer relatively often from TCs. In regions that do not suffer as regularly from TCs, data scarcity makes it even more difficult to anticipate adverse consequences. In these regions TCs are nevertheless often responsible for the most severe conditions, and the effects of such events should therefore be quantified in order be able to prepare for such conditions. For extreme cyclone wave conditions specifically, there is an additional problem of feasibly determining extreme wave conditions from cyclone wind conditions. This research presents the Tropical Cyclone Wind Statistical Estimation Tool (TCWiSE) to determine extreme TC wind speeds and focuses on the determination of its accuracy in data scarce regions. The tool was developed by applying it in a case study in the Gulf of Mexico. Moreover a brief qualitative assessment of the available TC wave models has been performed in order to identify an adequate method to determine extreme TC wave conditions from TC wind conditions.