Analysis on sea level variability along the coast of Haiphong Vietnam

The sea level variabilites along the coast of Haiphong, Vietnam are analyzed by the 52 years of hourly observations on the HONDAU tide gague. The results show that the long-term trends of the relative mean sea level change and the mean tidal range change are 1.98 mm/a and 3.07 mm/a, respectively. The harmonic tidal constants of main tidal constituents are changing, and have large correlation with the events of El Nino and La Nina. The Residual Sea Level (RSL) is rising with the rate of 1.76 mm/a, the mean positive and negative RSL is 12.48 cm and -13.36 cm, respectively. The cumulative frequency of the duration of the positive RSL and negative RSL less than 24h is 95.5% and 93.3%, repectively, and large than 48h is only about 1~2%. The absolute RSL less than 50cm occupy about 99%, and the positive and negative absolute RSL large than 100cm occupy about 0.1%. ©, 2015, Wuhan University. All right reserved.