Internal tides can have a signature of several centimeters at the ocean surface and need to be corrected from altimeter measurements. We present a detailed validation of several internal-tide models using existing satellite altimeter databases. The analysis focuses on the main diurnal and semidiurnal tidal constituents. Results show the interest of the methodology proposed, the quality of the internal-tide models tested and their positive contribution for estimating an accurate sea level.

The Liverpool Tidal Institute's (LTI) 100th anniversary was in 2019, and it acquired a reputation using tide prediction machines (TPMs). We describe the principles of a TPM, how many were made and Doodson's method to determine harmonic constants from tidal data to predict the tides. Although only three TPMs were used at the LTI, Doodson oversaw the design and manufacture of several others. We show how the UK, and Doodson particularly, played a central role in this area of science.

From the early work of Prince Albert I of Monaco, the first president of the International Association for the Physical Sciences of the Oceans, to today, the Association has promoted and supported international research and cross-cutting activities in ocean sciences, building on the work of the many far-sighted scientists who, over the last century, have addressed seemingly intractable problems. This paper describes key events in IAPSO's history and the roles played by the scientists involved.

This is the first investigation of the worldwide distribution of the degree-3 M1 ocean tide using over 800 tide gauge records and a global tide model. M1 is confirmed to have a geographical variation in the Atlantic and other basins consistent with the suggestion of Platzman and Cartwright that M1 is generated through the spatial and temporal overlap of M1 in the tidal potential and one (or at least a small number of) diurnal ocean normal mode(s).

30 years of BPR data at Drake Passage are used to investigate the Mf, Mm and Mt long-period tides. Amplitudes of Mf and Mt, and all phase lags, vary over the nodal cycle as in the equilibrium tide. Mm amplitude is almost constant, and so inconsistent at 3σ from anticipation due to energetic non-tidal variability. Most findings agree with a modern ocean tide model. BPR records are superior to conventional tide gauge data in this work due to lower proportion of non-tidal variability.

This paper discusses the quality of James Cook’s tidal measurements during the voyage of the Endeavour. We conclude that his measurements were accurate in general to about 0.5 ft in height and 30 min in time. They were good enough (or unique enough) to be included in global compilations of tidal information in the 18th century and were used in the 19th century in the construction of the first worldwide tidal atlases. They support Cook’s reputation as a good observer of the environment.

Mean sea level (MSL) is a prominent indicator of climatic change, and is therefore of great scientific and societal interest. Since the beginning of the altimeter mission TOPEX/Poseidon and its successors Jason-1 and Jason-2, MSL products became essential for climate applications. Since 1995, a suspicious signal is apparent in the corresponding MSL record. Since 2010, scientific teams have been working on reducing this error. This paper assesses, characterizes and quantifies this reduction.