Are Extreme Skew Surges Independent of High Water Levels in a Mixed Semidiurnal Tidal Regime?

Abstract

Based on previous studies of tide‐gauge records from locations with semidiurnal tidal regimes, extreme skew surges are always assumed independent of the high water (HW). However, differences in water depth between HW peaks of semidiurnal tidal regimes can be much lower than those in mixed semidiurnal regimes, where one daily HW is higher than the other. We statistically analyze tide‐gauge records of 15 sites worldwide with a mixed semidiurnal regime and find that for approximately half of these sites extreme skew surges occur more often during smaller HWs. This dependence is not caused by seasonality effects, and the places that show dependence are all located in areas with a shallow continental shelf, thus indicating possible tide‐skew surge interactions. In those cases where dependence exists, using the skew surge does not seem to offer any advantages over the nontidal residual.

A Flood Risk Framework Capturing the Seasonality of and Dependence Between Rainfall and Sea Levels—An Application to Ho Chi Minh City, Vietnam

“…(2013). While tide and skew surge can be dependent in mixed tidal regimes (Santamaria‐Aguilar & Vafeidis, 2018), here we find no dependence except for during the month of May (Text S1 in Supporting Information ). Figure S1 in Supporting Information compares the annual return levels per month with observed sea levels at the Vung Tau gauge which visually shows that our method reduces uncertainty and provides an appropriate fit for return periods higher than a 3‐year return period in a certain month.…”

“…Adding additional flood drivers in our model framework would increase the number of necessary hydrodynamic model runs exponentially, which could become a limiting factor to the feasibility of the analysis. In other locations, high tide and skew surge can exhibit a stronger dependence at the monthly time scale (Santamaria‐Aguilar & Vafeidis, 2018). In such case, the framework should be expanded to include this dependence.…”

Predictable Changes in Extreme Sea Levels and Coastal Flood Risk Due To Long‐Term Tidal Cycles

“…The probability distribution of sea levels ($${F}_{SL}$$) is calculated by computing the joint probability of the resulting skew surge distribution function and the ATNodal. Thus, we assume that the skew surge is independent of the tidal cycle, which has been shown to be statistically supported at most (though not all) coastal locations in past studies (Baranes et al., 2020; Batstone et al., 2013; Santamaria‐Aguilar & Vafeidis, 2018; Williams et al., 2016). The distribution function for the maximum sea level within a tidal cycle is, $$${F}_{SL}(z)={\left[{{\Pi}}_{t=1}^{M}{F}_{SS}\left(z-{P}_{t}\right)\right]}^{1/M}$$$ where $$z$$ is the sea level, $${P}_{t}$$ is the peak astronomical tide level at each cycle $$t$$, $$M$$ is the total number of peak astronomical tide levels, and $${F}_{SS}$$ is the cumulative distribution function of all skew surges.…”

“…The probability distribution of sea levels ( 𝐴𝐴 𝐴𝐴𝑆𝑆𝑆𝑆 ) is calculated by computing the joint probability of the resulting skew surge distribution function and the ATNodal. Thus, we assume that the skew surge is independent of the 10.1029/2021JC018157 5 of 13 tidal cycle, which has been shown to be statistically supported at most (though not all) coastal locations in past studies (Baranes et al, 2020;Batstone et al, 2013;Santamaria-Aguilar & Vafeidis, 2018;Williams et al, 2016). The distribution function for the maximum sea level within a tidal cycle is,…”

GESLA Version 3: A major update to the global higher-frequency sea-level dataset

“…Provision of information for flood inundation studies (e.g., Hunter et al, 2017); 4. Analysis of non-linear interactions between tides and non-tidal residuals or skew surges (e.g., Santamaria-Aguilar and Vafeidis, 2019;Arns et al, 2020); 5. Investigations of changes in ocean tidal constituents and levels (e.g., Schindelegger et al, 2018;Ray, 2020); 6.…”