Energy accumulation during the growth of forced wave induced by a moving atmospheric pressure disturbance

Abstract

ABSTRACTAtmospheric pressure disturbances of high translational speed can excite significant water waves, which are widely believed to be the main cause of destructive meteotsunamis. During the response of sea surface to adisturbance, energy is transferred from the atmosphere to the ocean, while the forced wave induced by the disturbance gradually grows and finally reaches a quasi-steady state. This study aims at quantifying the time required to excite the forced wave. Based on the nonlinear shallow water wave model, the evolution of the forced wave is numerically investigated. Analyses of the accumulation of wave energy are imported to help understand the evolution of the forced wave in different situations. The characteristics of energy accumulation show a great difference in the cases of different Froude number Fr. A parameter named response time is defined to quantify the time required for the evolution of the forced wave. It can be seen that Fr is the principal parameter that controls the wave evolution, while the effects of nonlinearity and bottom friction are significant only when Fr is close to 1. Simple relationships are proposed to roughly estimate the response time for Fr<0.9 and Fr>1.1, which can also provide a lower limit for Fr≈1.