Characteristics of astronomical tides and their modulation on sea level extremes along the Indian coast

摘要: In this study, long-term hourly sea-level records from 18 tide gauge stations during 1972–2007 were analyzed to study the characteristics of astronomical tides, sea-level trends, and extremes around India's mainland. The de-tided signals were used to estimate these parameters and study tide and surge interaction. The observed sea level depicts significant variability in daily, seasonal, and inter-annual time scales. Semidiurnal tides are the most dominant among the high-frequency tides, with an amplitude of up to 2.5 m for M2 and 0.75 m for S2 tides in the northwestern and northeastern continental shelf and reduced to 0.25 m in the south. The amplitude of diurnal tides (O1 and K1)is relatively weak (<0.25m) at all the stations. The annual harmonics dominate the seasonal cycle, with an amplitude of 0.7 m at Garden Reach in the northeastern continental shelf, decreases to 0.15 m at Tuticorin in the south, and …