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A meteorological tides forecasting method: first results in the Eastern Ligurian harbours
O. Faggioni, G. Arena, M. Bencivenga, G. Bianco, R. Bozzano, G. Canepa, P. Lusiani, G. Nardone, G. L. Piangiamore, M. Soldani, L. Surace, G. Venzano
INGV - Stazione di Geofisica Marina
faggioni@ingv.it(Abstract received 03/31/2005 for session C)
ABSTRACT
Sea level oscillations are the superposition of many contributions, among which the main are astronomic tides (astro-tides) and meteorological low-frequency components (meteo-tides). Particularly in the Ligurian Sea the meteo-tides, being most ample than the astronomic fluctuations, role the water exchange in harbours and the tide oscillations of coastal water masses (with particular reference to low-frequency sea level fluctuations). Moreover, this phenomenon has a primary role about environmental aspects, e.g. pollutants dispersion and water oxygenation balance. Meteorological tide is the geodetic adjustment of free sea surface to the variations of atmosphere weight burdening on it. The newtonian forecasting method of the meteorological tides is based on the measure of the time elapsing between the barometric sea level unbalance and its meteorological tide compensation. The meteorological tide component is independent on the Earth-Moon-Sun gravitational relationships, moreover the parameters related to the shifted water mass are too many to describe the phenomenon analytically. Then, meteorological tide can't be foreseen by the measurement of atmospheric pressure; on the contrary, meteo-tides can be foreseen by a statistic method starting from gravimetric measurements. In fact, a gravimeter can detect the time when the geodetic unbalance starts and a tide-gauge can detect the time when newtonian compensation happens by the arrival of tide wave. The difference between these two time-instants is the meteorological tide delay. An opportune statistic of this delay can provide an experimental law typical for each harbour to forecast the meteo-tide compensation wave delay and to plan human activities in the harbour waters. This work describes the methodological procedure adopted and the first experimental evidences of the phenomenon in Genoa and La Spezia harbours.
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2005 LAPCOD Meeting, Lerici, Italy, June 13-17, 2005