Session: 02-04-01 Extreme and Freak Waves (Co-hosted with the Ian Young Honoring Symposium)

Paper Number: 103377

103377 - Directional Wave Spectra During Hurricane Conditions Under Different Directional Spreading Formulations 

The directional wave spectra during hurricane conditions are not well-represented by numerical wave models like WAVEWATCH III (WW3) yet, which conditions the use of these tools with extreme waves hindcasting/forecasting purposes. Based on the ST6 source package, a sensitivity analysis with a set of modifications on the direction spreading formulations of wind input S_in and wave breaking dissipation S_ds are carried out in order to improve the ST6 performance estimating the directional wave spectra. Since the Discrete Interactions Approximation (DIA) algorithm is limited to simulate the directional features of the wave spectra under hurricane events, a regular storm is initially used to evaluate the changes on ST6. Thereafter, the well-observed hurricane Ivan (2004) is taken as a test case to verify the improvements on the directional spreading before a similar assessment over other tropical cyclones in the Caribbean sea and Gulf of Mexico. From the comparisons done between the available measurements (SRA and buoy data) and the simulations, we can conclude that the new directional distribution of S_ds source term generates a more precise representation of the wave systems that regularly occur during hurricane conditions. The overestimation (underestimation) of the swell (sea) systems is highly reduced as it was expected and it is also shown that the integral wave parameters keep in agreement with the measured values. Wave directionality variables such as mean wave direction and wave-spreading factor are included in the analysis as well and show a significant enhancement regarding previous studies except in a certain range of low frequencies where DIA usually is deficient. These modifications on the source terms in ST6 should be evaluated in other locations to generalize the results obtained here.

Presenting Author: Franklin Farid Ayala Cruz University of Melbourne

Presenting Author Biography: Franklin Ayala is doing his master degreen in water resources at the National University of Colombia and is currrently a visitor student in the ocean engineering research group at the University of Melbourne. He received a bachelor’s degree in civil engineering. He is interested in ocean waves hincast/forecast during tropical cyclones.

Authors:

Franklin Farid Ayala Cruz University of Melbourne
Alexander Babanin University of Melbourne
Qingxiang Liu Ocean University of China
Andrés Fernando Osorio Arias Universidad Nacional de Colombia - Sede Medellin
Rubén Darío Montoya Ramirez Universidad de Medellin