The Effect of Coastline Concavity on Maximum Storm Surge Height along the US Gulf Coast

Abstract

Storm surge is the most dangerous component of landfalling tropical cyclones (TCs). The growing coastal population highlights the importance of research regarding the atmospheric and geographic factors influencing the maximum storm surge height (MSSH). To date, few studies have investigated the influence of coastline concavity. Here, we investigate the hypothesis that TCs making landfall on a concave coastline will have a higher MSSH than TCs making landfall on a convex coastline. The Colorado State University extended best track dataset includes the radius of 34 kt winds (R34), landfall minimum mean sea level pressure (MSLP), landfall maximum sustained winds, and forward speed of TCs. The storm surge database for the US Gulf Coast provides the location and MSSH for TCs impacting the U.S. Gulf Coast. From this, eleven TCs that meet specific criteria and represent the larger population of Atlantic TCs are selected. The adjusted degree of coastline concavity (ADoC) is calculated for each TC using the law of cosines and 50, 100, and 200 km radius buffers around the point of MSSH. A Mann Whitney U test does not indicate any significant differences between the mean MSSH of TCs making landfall on each coastline type. Additionally, results from a simple linear regression F-test suggest that none of the included parameters have a significant influence on MSSH despite the findings of previous research. Still, the Spearman’s Rho correlation values suggest a weak positive relationship between the ADoC and MSSH. This relationship is significant at the 100 and 200 km buffers, which is consistent with the hypothesis. Results are limited by the small sample size. Future research should use a larger dataset and investigate how each individual storm characteristic affects MSSH. KEYWORDS: Tropical Cyclones; Hurricanes; Storm Surge; Coastal Geography; Coastline Concavity; Gulf of Mexico; Law of Cosines