Differences between mean tide level and mean sea level

Woodworth, P.L.. 2017 Differences between mean tide level and mean sea level. Journal of Geodesy, 91 (1). 69-90.

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© Springer Science+Business Media B.V. 2016 This document is the author’s final manuscript version of the journal article, incorporating any revisions agreed during the peer review process. Some differences between this and the publisher’s version remain. You are advised to consult the publisher’s version if you wish to cite from this article. The final publication is available at
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This paper discusses the differences between mean tide level (MTL) and mean sea level (MSL) as demonstrated using information from a global tide gauge data set. The roles of the two main contributors to differences between MTL and MSL (the M4 harmonic of the M2 semidiurnal tide, and the combination of the diurnal tides K1 and O1) are described, with a particular focus on the spatial scales of variation in MTL–MSL due to each contributor. Findings from the tide gauge data set are contrasted with those from a state-of-the-art global tide model. The study is of interest within tidal science, but also has practical importance regarding the type of mean level used to define land survey datums. In addition, an appreciation of MTL–MSL difference is important in the use of the historical sea level data used in climate change research, with implications for some of the data stored in international databanks. Particular studies are made of how MTL and MSL might differ through the year, and if MTL is measured in daylight hours only, as has been the practice of some national geodetic agencies on occasions in the past.

Item Type: Publication - Article
Digital Object Identifier (DOI):
ISSN: 0949-7714
Additional Keywords: Tide gauge measurements; Ocean tides; Hydrographic datums
Date made live: 27 Jul 2016 10:28 +0 (UTC)

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