Seasonal and spatial variations of kinematic parameters of internal solitary waves in the Andaman Sea

The horizontally variable density stratification and background currents are taken into the variable-coefficent extended Korteweg-de Vries (evKdV) theory to obtain the geographical and seasonal distribution of kinematic parameters of internal solitary waves in the Andaman Sea (AS). The kinematic parameters include phase speed, dispersion parameter, quadratic and cubic nonlinear parameters. It shows that the phase speed and dispersion parameter are mainly determined by the topographic feature and have limited seasonal variation. The maximum phase speed is 2.6 m/s, which occurs in the cool season (November) in the middle of the AS, while the phase speed in the cool season is slightly larger than those in other seasons, up to 11.4% larger than that in the rainy season (July) in the southern AS. The dispersion parameter in the cool season can be 22.3% larger than that in the hot season. The nonlinear parameters have significant seasonal variation, and they can even change their signs at the continental slope in the north of the AS, from season to season. Meanwhile, the algebraic solitons dominate in the AS with minimum amplitudes (a_al) ranging from 0.1 m to 102 m, and the maximum a_al occurs in the cool season in the southern AS. The effect of the background flow on the parameters is also studied. The background flow has a great influence on the nonlinear parameters, e.g., the value of cubic nonlinear parameter can be reduced by 1/3 when the background flow is not considered.