Sea level analysis off Alexandria, Egypt

Abstract

A one decade (1996–2005) of daily sea level records at Alexandria has been used to calculate both astronomical tide and surge elevations. The tidal harmonic constituents have been constructed using the T_TIDE program. Surge elevations have been calculated by subtracting the astronomical height from the observed sea level. The type factor of the tidal cycle at Alexandria has been calculated and specified the mixed mainly semidiurnal tide. The minimum annual Mean Sea Level (MSL) was 48.62 cm, while the maximum was 52.96 cm. The MSL over the study period is 50.67 cm. Thirty-five tidal constituents have been produced based on the present data. Both the Mm (Lunar monthly) and the Msf (Lunisolar synodic fortnightly) constituents in the present study have the largest constituent amplitudes, being 2.03 for the former and 7.06 for the later. The surge height over the study period varied between 14.64 and 87.15 cm, with an average of 50.66 cm. The results of the present research show that astronomical tide contributes with 0.005–37.63% while, surge contributes with 62.37–99.995% in the observed sea level.