Numerical study of the Middle Adriatic coastal waters' sensitivity to the various air pressure travelling disturbances

Abstract. The paper documents resonant coupling between an air pressure travelling disturbance and the Middle Adriatic coastal waters, examined theoretically by using a barotropic numerical model and then comparing the model to the observed events. The model is forced first with a cosine and box air pressure disturbance travelling with a constant speed and direction but varying its eulerian period/duration, whereas the sensitivity to the disturbance speed is examined by varying it, keeping all the other parameters constant. Larger resonant transfer of energy is documented for shorter disturbances and for the box versus cosine variation, especially in the high-frequency domain. Bands of enlarged sea level amplification are found in front of Stari Grad Bay (6.7 and 11.0 min) close to its natural modes (6.1 and 10.6 min), which may be a reason for the very large amplification and sporadic severe floods observed at the inner bay area. The lack of coincidence in the Stari Grad and Vela Luka observed floods may be partially a result of different disturbance speeds and energy transfer rates due to various depths off the bays, yet some additional factors (basin shape, real disturbance energy, disturbance direction) should be examined in the future.