Meteo-tsunami disintegration and soliton forerunners on Atchafalaya shelf, Lousiana

Uriah Gravois, University of Florida, Department of Civil and Coastal Engineering, Ft Walton Beach, FL, United States, Alexandru Sheremet, University of Florida, Engineering School of Sustainable Infrastructure & Environment, Gainesville, FL, United States; University of Florida, Department of Civil and Coastal Engineering, Gainesville, FL, United States and Victor I Shrira, Keele University, Staffordshire, ST5, United Kingdom
Abstract:
Field observations collected on the Atcahfalaya shelf in 2008 captured in high detail the shoaling evolution of a meteo-tsunami, including its disintegration into a undular bore. One of the intriguing elements of this process is a spectacular 1.5-m solitary-wave (soliton) forerunner, that precedes the arrival of the meteo-tsunami by approximately 5 min, reaching the observation site propagating through relatively calm waters (a wavefield of approximately 10-cm height).

The source of the meteo-tsunami is identified as a squall line associated with a strong atmospheric perturbation. An inverse ray method used to estimate the meteo-tsunami path suggests that the meteo-tsunami propagated as a trapped wave, originating in shallow water and ending in shallow water. The process of the generation of the soliton forerunner is investigated using the variable-coefficient KdV equation first proposed by Ostrovsky and Pelinovsky (1975). Numerical scenarios indicate that the soliton is the product of the collision of a shoaling "multiple-bump" tsunami structure. Given the natural irregularities of the generation mechanism of the meteo-tsunami, this suggests that such solitary-wave forrunners might be more common than expected.

Ostrovsky L.A., and E.N. Pelinovsky (1975). Refraction of nonlinear ocean waves in a beach zone. Izv Atmos Ocean Phys 11, 37–41.

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