On the complexity of the inversion of radar signatures of oceanic internal solitary waves into characteristics of the interior ocean

On August 22, 1997, a large-amplitude internal solitary wave was detected simultaneously by using in-situ and spaceborne synthetic aperture radar observations south of the Strait of Messina. The observed surface velocity field, together with wind speed and direction measured in-situ during the experiment, were inserted into a radar imaging model to calculate theoretical radar signatures. Good agreement was found between model results and observations. Several numerical simulations performed with the radar imaging model using different wind directions indicate that the simulated radar signatures depend strongly on this parameter which, in general, is not known accurately over the ocean. Inserting the measured undisturbed density stratification into an internal wave model, theoretical density and velocity fields associated with an internal solitary wave having the same amplitude as the observed one were calculated. Also in this case, good agreement was found between model results and observations. To study the dependence of the surface velocity field associated with an internal solitary wave on strength of the pycnocline and internal wave amplitude, several numerical simulations were performed with the internal wave model using three different density stratifications. The obtained model results can be seen as a measure of the complexity related to the inversion of sea surface manifestations of internal solitary waves into characteristics of the interior ocean.