The Quantification of Soliton Current Profiles for Offshore Engineering

Abstract

In widely used metocean terminology, solitons are large amplitude, often highly nonlinear, internal waves. They are responsible for complex vertical profiles of rapidly varying ocean currents. These current profiles need to be reliably quantified for a wide range of offshore engineering applications, often with very limited suitable data. Some recent advances in this field of applied research were described at OMAE2017 by Jeans et al (2017) [1]. Vertical displacements, derived from temperature measurements, were the primary input for soliton quantification. Associated current speeds were estimated from relevant theory and validated using available measured current data. This represents a notable development, because soliton current profiles are traditionally quantified via direct measurements of velocity. However, reliable current measurements can be a challenge, so the new approach is considered more reliable in some circumstances. Jeans et al (2017) [1] applied one simple and elegant theory for relating vertical displacement to velocity. This theory performed well, considering its limitations. This paper further evaluates different theoretical options, using a new dataset with much larger amplitude solitons. Theories with higher order nonlinearity are required for estimation of soliton current profiles in such challenging conditions.