Atmospheric tides in the area of Thessaloniki

The tidal changes of the barometric pressure in the area of Thessaloniki, Greece were investigated by analyzing a sample of 10.75 years of hourly measurements. The tidal analysis showed that the signal-to-noise ratio varies from 16.8 to 1 for the long period waves (Sa, Ssa, Mm, Mf). For the short period constituents, the corresponding quantity was negligible with the exception of the diurnal P1, S1, K1 and semidiurnal waves S2, K2 where values of 14, 93, 15 and 61 and 7 were found respectively. The amplitude and the phase difference of the above tidal waves were determined with an accuracy of 0.008-0.18 hPa and 1-3 degrees correspondingly. There is a considerable correlation of the surface temperature to the changes of the pressure affecting mainly the Ssa, S1 and S2 waves. The barometric changes computed in the area of Thessaloniki using the amplitude and phase difference determined through the tidal analysis reach a maximum amplitude equal to 10 hPa per year. It is also shown that the tidal changes of the barometric pressure in the test area correspond to about 37% of the total changes. A Fourier analysis of the daily mean values of the barometric pressure for the last 44 years showed significant amplitudes of the power spectral density (PSD) at the non-tidal periods of 8 and 52.6 days. Copyright (C) 1996 Elsevier Science Ltd