Influencia del viento y de las variaciones de la presión atmosférica en el nivel del mar de marismas y estuarios

Abstract

The article presents three formulas to predict long-term variations in sea level due not to astronomical tide but to weather effects such as the wind and changes in pressure of both seasonal and dynamic nature. In order to validate these formulas, an analysis was made of a series of sea level data recorded, over a period of three months, at two points in the Sancti Petri Channel spaced 5 km apart. Considerable variations were noted in the daily mean sea level and these variations have been shown to have been caused by changes in the atmospheric pressure. The differences are so large (as much as 26 cm in four days and 50 cm in six weeks) that they cannot be purely explained by the static inverted barometer effect (IBE) and we must then resort to a dynamic hypothesis. The adjusted values of the real IBE vary between 1.9 and 2.2 cm/mb, twice that generally employed. An easily applicable upper limit of the formula for the dynamic IBE is provided. On account of the form and the dimensions of the channel, the wind effect is negligible in this case. By way of conclusion it is indicated that any study attempting to establish the maximum sea levels in estuaries and salt marshes, in order to mark the boundaries of public-owned coastal zones or floodable areas, would require an examination of a series of data covering at least one year. If this is not the case, the forecast will always be lower than the real values.