Reply on CC1

Abstract

<strong class="journal-contentHeaderColor">Abstract.</strong> Total water levels (<em>TWL</em>s), including the contribution of wind waves, associated with tropical cyclones (TC) are among the most damaging hazards faced by coastal communities. According to the report of the Intergovernmental Panel on Climate Change (IPCC; Masson-Delmotte et al., 2021), TC&ndash;induced damages are expected to increase because of stronger TC intensity, sea level rise, and increased populations along the coasts. TC intensity, translation speed, and distance to the coast affect the magnitude and duration of increased <em>TWL</em>s and wind waves. Under climate change, the proportion of high&ndash;intensity TCs are projected to increase globally (IPCC; Masson-Delmotte et al., 2021), whereas the variation pattern of TC translation speed also depends on regions (Yamaguchi et al., 2020). There is an urgent need to improve our understanding of the linkages among TC characteristics and <em>TWL</em> components. In the past years, hurricanes Matthew (2016), Dorian (2019), and Isaias (2020) propagated over the South Atlantic Bight (SAB) with similar paths but resulted in different coastal impacts. We combined in situ observations and numerical simulations with the Coupled Ocean&ndash;Atmosphere&ndash;Wave&ndash;Sediment Transport (COAWST) modeling system to analyze the extreme <em>TWL</em>s under the three TCs. Model verification showed that the <em>TWL</em> components were well reproduced by the present model setup. Our results showed that peak <em>TWL</em> depends mainly on the TC intensity, the distance to the TC eye, and the TC heading direction. A decrease of TC translation speed primarily led to longer exceedance duration of <em>TWL</em>, which may lead to more severe damage. Wave&ndash;dependent water level components (i.e., wave setup and wave swash) were found to dominate the peak <em>TWL</em> within the near&ndash;TC wave field (60 %). Our results also showed that in specific conditions, the pre&ndash;storm wave runup associated with the TC&ndash;induced swell may lead to <em>TWL</em>s higher than at the peak of the storm. This was the case along the SAB during Hurricane Isaias. Isaias&rsquo;s fast TC translation speed and the fact that its swell was not blocked by any islands were the main factors contributing to these peak <em>TWL</em>s ahead of the storm peak.