12 Feb (CLIM) Orton, Flood Modeling for Tropical Cyclones

Philip Orton, Stevens Institute of Technology 

Why do tropical cyclone disasters surprise us in the mid-latitudes?  Insights from probabilistic and dynamical flood modeling 

Wed, 12 Feb, 1:30pm 

Innovation 134 and via Zoom (for link, email bklinger@gmu.edu) 

Host: Luis Ortiz 

A fundamental challenge with mid-latitude coastal storm hazard assessment is that tropical cyclones (TCs) cause the largest events but occur too infrequently to infer reliable hazard probability distributions. As a result, observation-based assessments of TC hazards typically merge TCs with far more numerous extra tropical cyclone (ETC) data, despite large differences between TCs and ETCs. 

First, I will demonstrate this challenge using synthetic storm surge data. Extreme value analysis (EVA) using merged TC and ETC data results in low-biased estimates of extremes. Separating storm types can eliminate this bias but suffers from greater random error. Longer datasets or model-based synthetic data can help reduce this error. 

Second, I will show how the threat of these TC “outlier” events can be accentuated by compounding hazards.  Results again show that TCs have unique characteristics and dominate the joint probabilities of the most extreme rain-surge compound events.