Atmospheric gravity waves and the ‘Rissaga’ phenomenon

✍ Scribed by S. Monserrat; A. Ibbetson; A. J. Thorpe

• Book ID: 104575947
• Publisher: John Wiley and Sons
• Year: 1991
• Tongue: English
• Weight: 1011 KB
• Volume: 117
• Category: Article
• ISSN: 0035-9009
• DOI: 10.1002/qj.49711749907

✦ Synopsis

Abstract

The atmospheric forcing of large sea‐level oscillations (up to 1.5 m amplitude with about a 10 min period) in some bays and inlets of the Balearic Islands is described using simultaneous measurements of pressure and sea‐level elevation in the port of Ciutadella (at the end of a large and narrow inlet) during 5–7 July 1989. The influence of atmospheric pressure oscillations on these large sea‐level variations, locally known as ‘rissaga’, is investigated. Coherence and cross‐correlation functions reveal that the large oscillations in the inlet are associated with and probably forced by a 10 min gravity wave in the atmosphere. The effect of longer‐period waves on the inlet is seen in the well‐known inverted barometric effect, forcing small oscillations in the water level of just some centimetres. These latter waves have a period of around 50 min and an unusually large amplitude of some 3 mb. The phase spectrum between sea level and pressure suggests that the inlet may behave as a damped harmonic oscillator which, during rissaga, is externally forced by the atmospheric pressure oscillations.