Water Surface Elevation Induced by an Accelerated Moving Atmospheric Pressure Disturbance

Abstract

The storm surge height is influenced by many factors. Effect of the constant moving atmospheric pressure disturbance (APD) (a steady case) on the water surface elevation has been studied previously. However in reality, the moving speed of the APD is generally changing with time, i.e., an unsteady situation with a certain moving acceleration. In this study, acceleration effect of APD on water surface elevation is investigated. Extending from the classic theoretical method proposed in Dean and Dalrymple (1991) for a steady case, an analytical solution is derived, which takes into account the effects of APD moving acceleration. Subsequently, acceleration effect on the water surface elevation is carried out with respect to two specified APD moving speeds under positive and negative accelerations. Upon which, comparison between the constant and accelerated moving speed cases is conducted. It is found that the maximum surface elevation under the accelerated case gradually shifts away from the APD center with time passing by, and positive and negative accelerations leads to different trends. Surface elevation difference between these two cases is affected by the time average moving speed and acceleration. In addition, temporal variation of the maximum surface elevation under the accelerated condition lags behind the relevant variation of the moving speed. Difference in time average surface elevation between these two cases is found to increase almost linearly with the acceleration. All these findings indicate the significance of acceleration effect on the water surface elevation estimation under the moving APD.